<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>
Class Mapping API
—
SQLAlchemy 1.2 Documentation
</title>
<!-- begin iterate through site-imported + sphinx environment css_files -->
<link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
<link rel="stylesheet" href="../_static/docs.css" type="text/css" />
<link rel="stylesheet" href="../_static/changelog.css" type="text/css" />
<link rel="stylesheet" href="../_static/sphinx_paramlinks.css" type="text/css" />
<!-- end iterate through site-imported + sphinx environment css_files -->
<!-- begin layout.mako headers -->
<link rel="index" title="Index" href="../genindex.html" />
<link rel="search" title="Search" href="../search.html" />
<link rel="copyright" title="Copyright" href="../copyright.html" />
<link rel="top" title="SQLAlchemy 1.2 Documentation" href="../index.html" />
<link rel="up" title="Mapper Configuration" href="mapper_config.html" />
<link rel="next" title="Relationship Configuration" href="relationships.html" />
<link rel="prev" title="Configuring a Version Counter" href="versioning.html" />
<!-- end layout.mako headers -->
</head>
<body>
<div id="docs-container">
<div id="docs-top-navigation-container" class="body-background">
<div id="docs-header">
<div id="docs-version-header">
Release: <span class="version-num">1.2.19</span>
| Release Date: April 15, 2019
</div>
<h1>SQLAlchemy 1.2 Documentation</h1>
</div>
</div>
<div id="docs-body-container">
<div id="fixed-sidebar" class="withsidebar">
<div id="docs-sidebar-popout">
<h3><a href="../index.html">SQLAlchemy 1.2 Documentation</a></h3>
<p id="sidebar-topnav">
<a href="../contents.html">Contents</a> |
<a href="../genindex.html">Index</a>
</p>
<div id="sidebar-search">
<form class="search" action="../search.html" method="get">
<label>
Search terms:
<input type="text" placeholder="search..." name="q" size="12" />
</label>
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
</div>
<div id="docs-sidebar">
<div id="sidebar-banner">
</div>
<div id="docs-sidebar-inner">
<h3>
<a href="index.html" title="SQLAlchemy ORM">SQLAlchemy ORM</a>
</h3>
<ul>
<li><span class="link-container"><a class="reference external" href="tutorial.html">Object Relational Tutorial</a></span></li>
<li><span class="link-container"><a class="reference external" href="mapper_config.html">Mapper Configuration</a></span><ul>
<li><span class="link-container"><a class="reference external" href="mapping_styles.html">Types of Mappings</a></span></li>
<li><span class="link-container"><a class="reference external" href="scalar_mapping.html">Mapping Columns and Expressions</a></span></li>
<li><span class="link-container"><a class="reference external" href="inheritance.html">Mapping Class Inheritance Hierarchies</a></span></li>
<li><span class="link-container"><a class="reference external" href="nonstandard_mappings.html">Non-Traditional Mappings</a></span></li>
<li><span class="link-container"><a class="reference external" href="versioning.html">Configuring a Version Counter</a></span></li>
<li class="selected"><span class="link-container"><strong>Class Mapping API</strong><a class="paramlink headerlink reference internal" href="#">¶</a></span></li>
</ul>
</li>
<li><span class="link-container"><a class="reference external" href="relationships.html">Relationship Configuration</a></span></li>
<li><span class="link-container"><a class="reference external" href="loading_objects.html">Loading Objects</a></span></li>
<li><span class="link-container"><a class="reference external" href="session.html">Using the Session</a></span></li>
<li><span class="link-container"><a class="reference external" href="extending.html">Events and Internals</a></span></li>
<li><span class="link-container"><a class="reference external" href="extensions/index.html">ORM Extensions</a></span></li>
<li><span class="link-container"><a class="reference external" href="examples.html">ORM Examples</a></span></li>
</ul>
</div>
</div>
</div>
<div id="docs-body" class="withsidebar" >
<span class="target" id="module-sqlalchemy.orm"></span><div class="section" id="class-mapping-api">
<h1>Class Mapping API<a class="headerlink" href="#class-mapping-api" title="Permalink to this headline">¶</a></h1>
<dl class="function">
<dt id="sqlalchemy.orm.mapper">
<code class="descclassname">sqlalchemy.orm.</code><code class="descname">mapper</code><span class="sig-paren">(</span><em>class_</em>, <em>local_table=None</em>, <em>properties=None</em>, <em>primary_key=None</em>, <em>non_primary=False</em>, <em>inherits=None</em>, <em>inherit_condition=None</em>, <em>inherit_foreign_keys=None</em>, <em>extension=None</em>, <em>order_by=False</em>, <em>always_refresh=False</em>, <em>version_id_col=None</em>, <em>version_id_generator=None</em>, <em>polymorphic_on=None</em>, <em>_polymorphic_map=None</em>, <em>polymorphic_identity=None</em>, <em>concrete=False</em>, <em>with_polymorphic=None</em>, <em>polymorphic_load=None</em>, <em>allow_partial_pks=True</em>, <em>batch=True</em>, <em>column_prefix=None</em>, <em>include_properties=None</em>, <em>exclude_properties=None</em>, <em>passive_updates=True</em>, <em>passive_deletes=False</em>, <em>confirm_deleted_rows=True</em>, <em>eager_defaults=False</em>, <em>legacy_is_orphan=False</em>, <em>_compiled_cache_size=100</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a new <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> object.</p>
<p>This function is typically used behind the scenes
via the Declarative extension. When using Declarative,
many of the usual <a class="reference internal" href="#sqlalchemy.orm.mapper" title="sqlalchemy.orm.mapper"><code class="xref py py-func docutils literal notranslate"><span class="pre">mapper()</span></code></a> arguments are handled
by the Declarative extension itself, including <code class="docutils literal notranslate"><span class="pre">class_</span></code>,
<code class="docutils literal notranslate"><span class="pre">local_table</span></code>, <code class="docutils literal notranslate"><span class="pre">properties</span></code>, and <code class="docutils literal notranslate"><span class="pre">inherits</span></code>.
Other options are passed to <a class="reference internal" href="#sqlalchemy.orm.mapper" title="sqlalchemy.orm.mapper"><code class="xref py py-func docutils literal notranslate"><span class="pre">mapper()</span></code></a> using
the <code class="docutils literal notranslate"><span class="pre">__mapper_args__</span></code> class variable:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">MyClass</span><span class="p">(</span><span class="n">Base</span><span class="p">):</span>
<span class="n">__tablename__</span> <span class="o">=</span> <span class="s1">'my_table'</span>
<span class="nb">id</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">Integer</span><span class="p">,</span> <span class="n">primary_key</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="nb">type</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">String</span><span class="p">(</span><span class="mi">50</span><span class="p">))</span>
<span class="n">alt</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="s2">"some_alt"</span><span class="p">,</span> <span class="n">Integer</span><span class="p">)</span>
<span class="n">__mapper_args__</span> <span class="o">=</span> <span class="p">{</span>
<span class="s1">'polymorphic_on'</span> <span class="p">:</span> <span class="nb">type</span>
<span class="p">}</span></pre></div>
</div>
<p>Explicit use of <a class="reference internal" href="#sqlalchemy.orm.mapper" title="sqlalchemy.orm.mapper"><code class="xref py py-func docutils literal notranslate"><span class="pre">mapper()</span></code></a>
is often referred to as <em>classical mapping</em>. The above
declarative example is equivalent in classical form to:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">my_table</span> <span class="o">=</span> <span class="n">Table</span><span class="p">(</span><span class="s2">"my_table"</span><span class="p">,</span> <span class="n">metadata</span><span class="p">,</span>
<span class="n">Column</span><span class="p">(</span><span class="s1">'id'</span><span class="p">,</span> <span class="n">Integer</span><span class="p">,</span> <span class="n">primary_key</span><span class="o">=</span><span class="kc">True</span><span class="p">),</span>
<span class="n">Column</span><span class="p">(</span><span class="s1">'type'</span><span class="p">,</span> <span class="n">String</span><span class="p">(</span><span class="mi">50</span><span class="p">)),</span>
<span class="n">Column</span><span class="p">(</span><span class="s2">"some_alt"</span><span class="p">,</span> <span class="n">Integer</span><span class="p">)</span>
<span class="p">)</span>
<span class="k">class</span> <span class="nc">MyClass</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="k">pass</span>
<span class="n">mapper</span><span class="p">(</span><span class="n">MyClass</span><span class="p">,</span> <span class="n">my_table</span><span class="p">,</span>
<span class="n">polymorphic_on</span><span class="o">=</span><span class="n">my_table</span><span class="o">.</span><span class="n">c</span><span class="o">.</span><span class="n">type</span><span class="p">,</span>
<span class="n">properties</span><span class="o">=</span><span class="p">{</span>
<span class="s1">'alt'</span><span class="p">:</span><span class="n">my_table</span><span class="o">.</span><span class="n">c</span><span class="o">.</span><span class="n">some_alt</span>
<span class="p">})</span></pre></div>
</div>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="mapping_styles.html#classical-mapping"><span class="std std-ref">Classical Mappings</span></a> - discussion of direct usage of
<a class="reference internal" href="#sqlalchemy.orm.mapper" title="sqlalchemy.orm.mapper"><code class="xref py py-func docutils literal notranslate"><span class="pre">mapper()</span></code></a></p>
</div>
<dl class="field-list simple">
<dt class="field-odd">Parameters</dt>
<dd class="field-odd"><ul class="simple">
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.class_"></span><strong>class_</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.class_">¶</a> – The class to be mapped. When using Declarative,
this argument is automatically passed as the declared class
itself.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.local_table"></span><strong>local_table</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.local_table">¶</a> – The <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><code class="xref py py-class docutils literal notranslate"><span class="pre">Table</span></code></a> or other selectable
to which the class is mapped. May be <code class="docutils literal notranslate"><span class="pre">None</span></code> if
this mapper inherits from another mapper using single-table
inheritance. When using Declarative, this argument is
automatically passed by the extension, based on what
is configured via the <code class="docutils literal notranslate"><span class="pre">__table__</span></code> argument or via the
<a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><code class="xref py py-class docutils literal notranslate"><span class="pre">Table</span></code></a> produced as a result of the <code class="docutils literal notranslate"><span class="pre">__tablename__</span></code>
and <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a> arguments present.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.always_refresh"></span><strong>always_refresh</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.always_refresh">¶</a> – If True, all query operations for this mapped
class will overwrite all data within object instances that already
exist within the session, erasing any in-memory changes with
whatever information was loaded from the database. Usage of this
flag is highly discouraged; as an alternative, see the method
<a class="reference internal" href="query.html#sqlalchemy.orm.query.Query.populate_existing" title="sqlalchemy.orm.query.Query.populate_existing"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Query.populate_existing()</span></code></a>.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.allow_partial_pks"></span><strong>allow_partial_pks</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.allow_partial_pks">¶</a> – Defaults to True. Indicates that a
composite primary key with some NULL values should be considered as
possibly existing within the database. This affects whether a
mapper will assign an incoming row to an existing identity, as well
as if <a class="reference internal" href="session_api.html#sqlalchemy.orm.session.Session.merge" title="sqlalchemy.orm.session.Session.merge"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Session.merge()</span></code></a> will check the database first for a
particular primary key value. A “partial primary key” can occur if
one has mapped to an OUTER JOIN, for example.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.batch"></span><strong>batch</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.batch">¶</a> – Defaults to <code class="docutils literal notranslate"><span class="pre">True</span></code>, indicating that save operations
of multiple entities can be batched together for efficiency.
Setting to False indicates
that an instance will be fully saved before saving the next
instance. This is used in the extremely rare case that a
<a class="reference internal" href="events.html#sqlalchemy.orm.events.MapperEvents" title="sqlalchemy.orm.events.MapperEvents"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperEvents</span></code></a> listener requires being called
in between individual row persistence operations.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.column_prefix"></span><strong>column_prefix</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.column_prefix">¶</a> – <p>A string which will be prepended
to the mapped attribute name when <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a>
objects are automatically assigned as attributes to the
mapped class. Does not affect explicitly specified
column-based properties.</p>
<p>See the section <a class="reference internal" href="mapping_columns.html#column-prefix"><span class="std std-ref">Naming All Columns with a Prefix</span></a> for an example.</p>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.concrete"></span><strong>concrete</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.concrete">¶</a> – <p>If True, indicates this mapper should use concrete
table inheritance with its parent mapper.</p>
<p>See the section <a class="reference internal" href="inheritance.html#concrete-inheritance"><span class="std std-ref">Concrete Table Inheritance</span></a> for an example.</p>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.confirm_deleted_rows"></span><strong>confirm_deleted_rows</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.confirm_deleted_rows">¶</a> – <p>defaults to True; when a DELETE occurs
of one more rows based on specific primary keys, a warning is
emitted when the number of rows matched does not equal the number
of rows expected. This parameter may be set to False to handle the
case where database ON DELETE CASCADE rules may be deleting some of
those rows automatically. The warning may be changed to an
exception in a future release.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 0.9.4: </span>- added
<a class="reference internal" href="#sqlalchemy.orm.mapper.params.confirm_deleted_rows" title="sqlalchemy.orm.mapper"><code class="xref py py-paramref docutils literal notranslate"><span class="pre">mapper.confirm_deleted_rows</span></code></a> as well as conditional
matched row checking on delete.</p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.eager_defaults"></span><strong>eager_defaults</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.eager_defaults">¶</a> – <p>if True, the ORM will immediately fetch the
value of server-generated default values after an INSERT or UPDATE,
rather than leaving them as expired to be fetched on next access.
This can be used for event schemes where the server-generated values
are needed immediately before the flush completes. By default,
this scheme will emit an individual <code class="docutils literal notranslate"><span class="pre">SELECT</span></code> statement per row
inserted or updated, which note can add significant performance
overhead. However, if the
target database supports <a class="reference internal" href="../glossary.html#term-returning"><span class="xref std std-term">RETURNING</span></a>, the default values will
be returned inline with the INSERT or UPDATE statement, which can
greatly enhance performance for an application that needs frequent
access to just-generated server defaults.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="persistence_techniques.html#orm-server-defaults"><span class="std std-ref">Fetching Server-Generated Defaults</span></a></p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 0.9.0: </span>The <code class="docutils literal notranslate"><span class="pre">eager_defaults</span></code> option can now
make use of <a class="reference internal" href="../glossary.html#term-returning"><span class="xref std std-term">RETURNING</span></a> for backends which support it.</p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.exclude_properties"></span><strong>exclude_properties</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.exclude_properties">¶</a> – <p>A list or set of string column names to
be excluded from mapping.</p>
<p>See <a class="reference internal" href="mapping_columns.html#include-exclude-cols"><span class="std std-ref">Mapping a Subset of Table Columns</span></a> for an example.</p>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.extension"></span><strong>extension</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.extension">¶</a> – <p>A <a class="reference internal" href="deprecated.html#sqlalchemy.orm.interfaces.MapperExtension" title="sqlalchemy.orm.interfaces.MapperExtension"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperExtension</span></code></a> instance or
list of <a class="reference internal" href="deprecated.html#sqlalchemy.orm.interfaces.MapperExtension" title="sqlalchemy.orm.interfaces.MapperExtension"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperExtension</span></code></a> instances which will be applied
to all operations by this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>.</p>
<div class="deprecated">
<p><span class="versionmodified deprecated">Deprecated since version 0.7: </span><a class="reference internal" href="deprecated.html#sqlalchemy.orm.interfaces.MapperExtension" title="sqlalchemy.orm.interfaces.MapperExtension"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperExtension</span></code></a> is deprecated in favor of the
<a class="reference internal" href="events.html#sqlalchemy.orm.events.MapperEvents" title="sqlalchemy.orm.events.MapperEvents"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperEvents</span></code></a> listener interface. The
<a class="reference internal" href="#sqlalchemy.orm.mapper.params.extension" title="sqlalchemy.orm.mapper"><code class="xref py py-paramref docutils literal notranslate"><span class="pre">mapper.extension</span></code></a> parameter will be
removed in a future release.</p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.include_properties"></span><strong>include_properties</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.include_properties">¶</a> – <p>An inclusive list or set of string column
names to map.</p>
<p>See <a class="reference internal" href="mapping_columns.html#include-exclude-cols"><span class="std std-ref">Mapping a Subset of Table Columns</span></a> for an example.</p>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.inherits"></span><strong>inherits</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.inherits">¶</a> – <p>A mapped class or the corresponding <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>
of one indicating a superclass to which this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>
should <em>inherit</em> from. The mapped class here must be a subclass
of the other mapper’s class. When using Declarative, this argument
is passed automatically as a result of the natural class
hierarchy of the declared classes.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="inheritance.html"><span class="std std-ref">Mapping Class Inheritance Hierarchies</span></a></p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.inherit_condition"></span><strong>inherit_condition</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.inherit_condition">¶</a> – For joined table inheritance, a SQL
expression which will
define how the two tables are joined; defaults to a natural join
between the two tables.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.inherit_foreign_keys"></span><strong>inherit_foreign_keys</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.inherit_foreign_keys">¶</a> – When <code class="docutils literal notranslate"><span class="pre">inherit_condition</span></code> is used and
the columns present are missing a <a class="reference internal" href="../core/constraints.html#sqlalchemy.schema.ForeignKey" title="sqlalchemy.schema.ForeignKey"><code class="xref py py-class docutils literal notranslate"><span class="pre">ForeignKey</span></code></a>
configuration, this parameter can be used to specify which columns
are “foreign”. In most cases can be left as <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.legacy_is_orphan"></span><strong>legacy_is_orphan</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.legacy_is_orphan">¶</a> – <p>Boolean, defaults to <code class="docutils literal notranslate"><span class="pre">False</span></code>.
When <code class="docutils literal notranslate"><span class="pre">True</span></code>, specifies that “legacy” orphan consideration
is to be applied to objects mapped by this mapper, which means
that a pending (that is, not persistent) object is auto-expunged
from an owning <a class="reference internal" href="session_api.html#sqlalchemy.orm.session.Session" title="sqlalchemy.orm.session.Session"><code class="xref py py-class docutils literal notranslate"><span class="pre">Session</span></code></a> only when it is de-associated
from <em>all</em> parents that specify a <code class="docutils literal notranslate"><span class="pre">delete-orphan</span></code> cascade towards
this mapper. The new default behavior is that the object is
auto-expunged when it is de-associated with <em>any</em> of its parents
that specify <code class="docutils literal notranslate"><span class="pre">delete-orphan</span></code> cascade. This behavior is more
consistent with that of a persistent object, and allows behavior to
be consistent in more scenarios independently of whether or not an
orphanable object has been flushed yet or not.</p>
<p>See the change note and example at <a class="reference internal" href="../changelog/migration_08.html#legacy-is-orphan-addition"><span class="std std-ref">The consideration of a “pending” object as an “orphan” has been made more aggressive</span></a>
for more detail on this change.</p>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.non_primary"></span><strong>non_primary</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.non_primary">¶</a> – <p>Specify that this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> is in addition
to the “primary” mapper, that is, the one used for persistence.
The <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> created here may be used for ad-hoc
mapping of the class to an alternate selectable, for loading
only.</p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.params.non_primary" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-paramref docutils literal notranslate"><span class="pre">Mapper.non_primary</span></code></a> is not an often used option, but
is useful in some specific <a class="reference internal" href="relationship_api.html#sqlalchemy.orm.relationship" title="sqlalchemy.orm.relationship"><code class="xref py py-func docutils literal notranslate"><span class="pre">relationship()</span></code></a> cases.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="join_conditions.html#relationship-non-primary-mapper"><span class="std std-ref">Relationship to Non Primary Mapper</span></a></p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.order_by"></span><strong>order_by</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.order_by">¶</a> – <p>A single <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a> or list of <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a>
objects for which selection operations should use as the default
ordering for entities. By default mappers have no pre-defined
ordering.</p>
<div class="deprecated">
<p><span class="versionmodified deprecated">Deprecated since version 1.1: </span>The <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.params.order_by" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-paramref docutils literal notranslate"><span class="pre">Mapper.order_by</span></code></a> parameter
is deprecated, and will be removed in a future release.
Use <a class="reference internal" href="query.html#sqlalchemy.orm.query.Query.order_by" title="sqlalchemy.orm.query.Query.order_by"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Query.order_by()</span></code></a> to determine the ordering of a
result set.</p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.passive_deletes"></span><strong>passive_deletes</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.passive_deletes">¶</a> – <p>Indicates DELETE behavior of foreign key
columns when a joined-table inheritance entity is being deleted.
Defaults to <code class="docutils literal notranslate"><span class="pre">False</span></code> for a base mapper; for an inheriting mapper,
defaults to <code class="docutils literal notranslate"><span class="pre">False</span></code> unless the value is set to <code class="docutils literal notranslate"><span class="pre">True</span></code>
on the superclass mapper.</p>
<p>When <code class="docutils literal notranslate"><span class="pre">True</span></code>, it is assumed that ON DELETE CASCADE is configured
on the foreign key relationships that link this mapper’s table
to its superclass table, so that when the unit of work attempts
to delete the entity, it need only emit a DELETE statement for the
superclass table, and not this table.</p>
<p>When <code class="docutils literal notranslate"><span class="pre">False</span></code>, a DELETE statement is emitted for this mapper’s
table individually. If the primary key attributes local to this
table are unloaded, then a SELECT must be emitted in order to
validate these attributes; note that the primary key columns
of a joined-table subclass are not part of the “primary key” of
the object as a whole.</p>
<p>Note that a value of <code class="docutils literal notranslate"><span class="pre">True</span></code> is <strong>always</strong> forced onto the
subclass mappers; that is, it’s not possible for a superclass
to specify passive_deletes without this taking effect for
all subclass mappers.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 1.1.</span></p>
</div>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="collections.html#passive-deletes"><span class="std std-ref">Using Passive Deletes</span></a> - description of similar feature as
used with <a class="reference internal" href="relationship_api.html#sqlalchemy.orm.relationship" title="sqlalchemy.orm.relationship"><code class="xref py py-func docutils literal notranslate"><span class="pre">relationship()</span></code></a></p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.params.passive_updates" title="sqlalchemy.orm.mapper"><code class="xref py py-paramref docutils literal notranslate"><span class="pre">mapper.passive_updates</span></code></a> - supporting ON UPDATE
CASCADE for joined-table inheritance mappers</p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.passive_updates"></span><strong>passive_updates</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.passive_updates">¶</a> – <p>Indicates UPDATE behavior of foreign key
columns when a primary key column changes on a joined-table
inheritance mapping. Defaults to <code class="docutils literal notranslate"><span class="pre">True</span></code>.</p>
<p>When True, it is assumed that ON UPDATE CASCADE is configured on
the foreign key in the database, and that the database will handle
propagation of an UPDATE from a source column to dependent columns
on joined-table rows.</p>
<p>When False, it is assumed that the database does not enforce
referential integrity and will not be issuing its own CASCADE
operation for an update. The unit of work process will
emit an UPDATE statement for the dependent columns during a
primary key change.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="relationship_persistence.html#passive-updates"><span class="std std-ref">Mutable Primary Keys / Update Cascades</span></a> - description of a similar feature as
used with <a class="reference internal" href="relationship_api.html#sqlalchemy.orm.relationship" title="sqlalchemy.orm.relationship"><code class="xref py py-func docutils literal notranslate"><span class="pre">relationship()</span></code></a></p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.params.passive_deletes" title="sqlalchemy.orm.mapper"><code class="xref py py-paramref docutils literal notranslate"><span class="pre">mapper.passive_deletes</span></code></a> - supporting ON DELETE
CASCADE for joined-table inheritance mappers</p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.polymorphic_load"></span><strong>polymorphic_load</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.polymorphic_load">¶</a> – <dl>
<dt>Specifies “polymorphic loading” behavior</dt><dd><p>for a subclass in an inheritance hierarchy (joined and single
table inheritance only). Valid values are:</p>
<blockquote>
<div><ul>
<li><p>“‘inline’” - specifies this class should be part of the
“with_polymorphic” mappers, e.g. its columns will be included
in a SELECT query against the base.</p></li>
<li><p>“‘selectin’” - specifies that when instances of this class
are loaded, an additional SELECT will be emitted to retrieve
the columns specific to this subclass. The SELECT uses
IN to fetch multiple subclasses at once.</p></li>
</ul>
</div></blockquote>
</dd>
</dl>
<div class="versionadded">
<p><span class="versionmodified added">New in version 1.2.</span></p>
</div>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="inheritance_loading.html#with-polymorphic-mapper-config"><span class="std std-ref">Setting with_polymorphic at mapper configuration time</span></a></p>
<p><a class="reference internal" href="inheritance_loading.html#polymorphic-selectin"><span class="std std-ref">Polymorphic Selectin Loading</span></a></p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.polymorphic_on"></span><strong>polymorphic_on</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.polymorphic_on">¶</a> – <p>Specifies the column, attribute, or
SQL expression used to determine the target class for an
incoming row, when inheriting classes are present.</p>
<p>This value is commonly a <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a> object that’s
present in the mapped <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><code class="xref py py-class docutils literal notranslate"><span class="pre">Table</span></code></a>:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Employee</span><span class="p">(</span><span class="n">Base</span><span class="p">):</span>
<span class="n">__tablename__</span> <span class="o">=</span> <span class="s1">'employee'</span>
<span class="nb">id</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">Integer</span><span class="p">,</span> <span class="n">primary_key</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="n">discriminator</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">String</span><span class="p">(</span><span class="mi">50</span><span class="p">))</span>
<span class="n">__mapper_args__</span> <span class="o">=</span> <span class="p">{</span>
<span class="s2">"polymorphic_on"</span><span class="p">:</span><span class="n">discriminator</span><span class="p">,</span>
<span class="s2">"polymorphic_identity"</span><span class="p">:</span><span class="s2">"employee"</span>
<span class="p">}</span></pre></div>
</div>
<p>It may also be specified
as a SQL expression, as in this example where we
use the <a class="reference internal" href="../core/sqlelement.html#sqlalchemy.sql.expression.case" title="sqlalchemy.sql.expression.case"><code class="xref py py-func docutils literal notranslate"><span class="pre">case()</span></code></a> construct to provide a conditional
approach:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Employee</span><span class="p">(</span><span class="n">Base</span><span class="p">):</span>
<span class="n">__tablename__</span> <span class="o">=</span> <span class="s1">'employee'</span>
<span class="nb">id</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">Integer</span><span class="p">,</span> <span class="n">primary_key</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="n">discriminator</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">String</span><span class="p">(</span><span class="mi">50</span><span class="p">))</span>
<span class="n">__mapper_args__</span> <span class="o">=</span> <span class="p">{</span>
<span class="s2">"polymorphic_on"</span><span class="p">:</span><span class="n">case</span><span class="p">([</span>
<span class="p">(</span><span class="n">discriminator</span> <span class="o">==</span> <span class="s2">"EN"</span><span class="p">,</span> <span class="s2">"engineer"</span><span class="p">),</span>
<span class="p">(</span><span class="n">discriminator</span> <span class="o">==</span> <span class="s2">"MA"</span><span class="p">,</span> <span class="s2">"manager"</span><span class="p">),</span>
<span class="p">],</span> <span class="n">else_</span><span class="o">=</span><span class="s2">"employee"</span><span class="p">),</span>
<span class="s2">"polymorphic_identity"</span><span class="p">:</span><span class="s2">"employee"</span>
<span class="p">}</span></pre></div>
</div>
<p>It may also refer to any attribute
configured with <a class="reference internal" href="mapping_columns.html#sqlalchemy.orm.column_property" title="sqlalchemy.orm.column_property"><code class="xref py py-func docutils literal notranslate"><span class="pre">column_property()</span></code></a>, or to the
string name of one:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Employee</span><span class="p">(</span><span class="n">Base</span><span class="p">):</span>
<span class="n">__tablename__</span> <span class="o">=</span> <span class="s1">'employee'</span>
<span class="nb">id</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">Integer</span><span class="p">,</span> <span class="n">primary_key</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="n">discriminator</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">String</span><span class="p">(</span><span class="mi">50</span><span class="p">))</span>
<span class="n">employee_type</span> <span class="o">=</span> <span class="n">column_property</span><span class="p">(</span>
<span class="n">case</span><span class="p">([</span>
<span class="p">(</span><span class="n">discriminator</span> <span class="o">==</span> <span class="s2">"EN"</span><span class="p">,</span> <span class="s2">"engineer"</span><span class="p">),</span>
<span class="p">(</span><span class="n">discriminator</span> <span class="o">==</span> <span class="s2">"MA"</span><span class="p">,</span> <span class="s2">"manager"</span><span class="p">),</span>
<span class="p">],</span> <span class="n">else_</span><span class="o">=</span><span class="s2">"employee"</span><span class="p">)</span>
<span class="p">)</span>
<span class="n">__mapper_args__</span> <span class="o">=</span> <span class="p">{</span>
<span class="s2">"polymorphic_on"</span><span class="p">:</span><span class="n">employee_type</span><span class="p">,</span>
<span class="s2">"polymorphic_identity"</span><span class="p">:</span><span class="s2">"employee"</span>
<span class="p">}</span></pre></div>
</div>
<p>When setting <code class="docutils literal notranslate"><span class="pre">polymorphic_on</span></code> to reference an
attribute or expression that’s not present in the
locally mapped <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><code class="xref py py-class docutils literal notranslate"><span class="pre">Table</span></code></a>, yet the value
of the discriminator should be persisted to the database,
the value of the
discriminator is not automatically set on new
instances; this must be handled by the user,
either through manual means or via event listeners.
A typical approach to establishing such a listener
looks like:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">event</span>
<span class="kn">from</span> <span class="nn">sqlalchemy.orm</span> <span class="k">import</span> <span class="n">object_mapper</span>
<span class="nd">@event</span><span class="o">.</span><span class="n">listens_for</span><span class="p">(</span><span class="n">Employee</span><span class="p">,</span> <span class="s2">"init"</span><span class="p">,</span> <span class="n">propagate</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">set_identity</span><span class="p">(</span><span class="n">instance</span><span class="p">,</span> <span class="o">*</span><span class="n">arg</span><span class="p">,</span> <span class="o">**</span><span class="n">kw</span><span class="p">):</span>
<span class="n">mapper</span> <span class="o">=</span> <span class="n">object_mapper</span><span class="p">(</span><span class="n">instance</span><span class="p">)</span>
<span class="n">instance</span><span class="o">.</span><span class="n">discriminator</span> <span class="o">=</span> <span class="n">mapper</span><span class="o">.</span><span class="n">polymorphic_identity</span></pre></div>
</div>
<p>Where above, we assign the value of <code class="docutils literal notranslate"><span class="pre">polymorphic_identity</span></code>
for the mapped class to the <code class="docutils literal notranslate"><span class="pre">discriminator</span></code> attribute,
thus persisting the value to the <code class="docutils literal notranslate"><span class="pre">discriminator</span></code> column
in the database.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Currently, <strong>only one discriminator column may be set</strong>, typically
on the base-most class in the hierarchy. “Cascading” polymorphic
columns are not yet supported.</p>
</div>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="inheritance.html"><span class="std std-ref">Mapping Class Inheritance Hierarchies</span></a></p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.polymorphic_identity"></span><strong>polymorphic_identity</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.polymorphic_identity">¶</a> – Specifies the value which
identifies this particular class as returned by the
column expression referred to by the <code class="docutils literal notranslate"><span class="pre">polymorphic_on</span></code>
setting. As rows are received, the value corresponding
to the <code class="docutils literal notranslate"><span class="pre">polymorphic_on</span></code> column expression is compared
to this value, indicating which subclass should
be used for the newly reconstructed object.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.properties"></span><strong>properties</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.properties">¶</a> – A dictionary mapping the string names of object
attributes to <a class="reference internal" href="internals.html#sqlalchemy.orm.interfaces.MapperProperty" title="sqlalchemy.orm.interfaces.MapperProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperProperty</span></code></a> instances, which define the
persistence behavior of that attribute. Note that <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a>
objects present in
the mapped <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><code class="xref py py-class docutils literal notranslate"><span class="pre">Table</span></code></a> are automatically placed into
<code class="docutils literal notranslate"><span class="pre">ColumnProperty</span></code> instances upon mapping, unless overridden.
When using Declarative, this argument is passed automatically,
based on all those <a class="reference internal" href="internals.html#sqlalchemy.orm.interfaces.MapperProperty" title="sqlalchemy.orm.interfaces.MapperProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperProperty</span></code></a> instances declared
in the declared class body.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.primary_key"></span><strong>primary_key</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.primary_key">¶</a> – A list of <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a> objects which define
the primary key to be used against this mapper’s selectable unit.
This is normally simply the primary key of the <code class="docutils literal notranslate"><span class="pre">local_table</span></code>, but
can be overridden here.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.version_id_col"></span><strong>version_id_col</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.version_id_col">¶</a> – <p>A <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a>
that will be used to keep a running version id of rows
in the table. This is used to detect concurrent updates or
the presence of stale data in a flush. The methodology is to
detect if an UPDATE statement does not match the last known
version id, a
<a class="reference internal" href="exceptions.html#sqlalchemy.orm.exc.StaleDataError" title="sqlalchemy.orm.exc.StaleDataError"><code class="xref py py-class docutils literal notranslate"><span class="pre">StaleDataError</span></code></a> exception is
thrown.
By default, the column must be of <a class="reference internal" href="../core/type_basics.html#sqlalchemy.types.Integer" title="sqlalchemy.types.Integer"><code class="xref py py-class docutils literal notranslate"><span class="pre">Integer</span></code></a> type,
unless <code class="docutils literal notranslate"><span class="pre">version_id_generator</span></code> specifies an alternative version
generator.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="versioning.html#mapper-version-counter"><span class="std std-ref">Configuring a Version Counter</span></a> - discussion of version counting
and rationale.</p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.version_id_generator"></span><strong>version_id_generator</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.version_id_generator">¶</a> – <p>Define how new version ids should
be generated. Defaults to <code class="docutils literal notranslate"><span class="pre">None</span></code>, which indicates that
a simple integer counting scheme be employed. To provide a custom
versioning scheme, provide a callable function of the form:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">generate_version</span><span class="p">(</span><span class="n">version</span><span class="p">):</span>
<span class="k">return</span> <span class="n">next_version</span></pre></div>
</div>
<p>Alternatively, server-side versioning functions such as triggers,
or programmatic versioning schemes outside of the version id
generator may be used, by specifying the value <code class="docutils literal notranslate"><span class="pre">False</span></code>.
Please see <a class="reference internal" href="versioning.html#server-side-version-counter"><span class="std std-ref">Server Side Version Counters</span></a> for a discussion
of important points when using this option.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 0.9.0: </span><code class="docutils literal notranslate"><span class="pre">version_id_generator</span></code> supports
server-side version number generation.</p>
</div>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="versioning.html#custom-version-counter"><span class="std std-ref">Custom Version Counters / Types</span></a></p>
<p><a class="reference internal" href="versioning.html#server-side-version-counter"><span class="std std-ref">Server Side Version Counters</span></a></p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.params.with_polymorphic"></span><strong>with_polymorphic</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.params.with_polymorphic">¶</a> – <p>A tuple in the form <code class="docutils literal notranslate"><span class="pre">(<classes>,</span>
<span class="pre"><selectable>)</span></code> indicating the default style of “polymorphic”
loading, that is, which tables are queried at once. <classes> is
any single or list of mappers and/or classes indicating the
inherited classes that should be loaded at once. The special value
<code class="docutils literal notranslate"><span class="pre">'*'</span></code> may be used to indicate all descending classes should be
loaded immediately. The second tuple argument <selectable>
indicates a selectable that will be used to query for multiple
classes.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="inheritance_loading.html#with-polymorphic"><span class="std std-ref">Using with_polymorphic</span></a> - discussion of polymorphic querying
techniques.</p>
</div>
</p></li>
</ul>
</dd>
</dl>
</dd></dl>
<dl class="function">
<dt id="sqlalchemy.orm.object_mapper">
<code class="descclassname">sqlalchemy.orm.</code><code class="descname">object_mapper</code><span class="sig-paren">(</span><em>instance</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.object_mapper" title="Permalink to this definition">¶</a></dt>
<dd><p>Given an object, return the primary Mapper associated with the object
instance.</p>
<p>Raises <a class="reference internal" href="exceptions.html#sqlalchemy.orm.exc.UnmappedInstanceError" title="sqlalchemy.orm.exc.UnmappedInstanceError"><code class="xref py py-class docutils literal notranslate"><span class="pre">sqlalchemy.orm.exc.UnmappedInstanceError</span></code></a>
if no mapping is configured.</p>
<p>This function is available via the inspection system as:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">inspect</span><span class="p">(</span><span class="n">instance</span><span class="p">)</span><span class="o">.</span><span class="n">mapper</span></pre></div>
</div>
<p>Using the inspection system will raise
<a class="reference internal" href="../core/exceptions.html#sqlalchemy.exc.NoInspectionAvailable" title="sqlalchemy.exc.NoInspectionAvailable"><code class="xref py py-class docutils literal notranslate"><span class="pre">sqlalchemy.exc.NoInspectionAvailable</span></code></a> if the instance is
not part of a mapping.</p>
</dd></dl>
<dl class="function">
<dt id="sqlalchemy.orm.class_mapper">
<code class="descclassname">sqlalchemy.orm.</code><code class="descname">class_mapper</code><span class="sig-paren">(</span><em>class_</em>, <em>configure=True</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.class_mapper" title="Permalink to this definition">¶</a></dt>
<dd><p>Given a class, return the primary <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> associated
with the key.</p>
<p>Raises <a class="reference internal" href="exceptions.html#sqlalchemy.orm.exc.UnmappedClassError" title="sqlalchemy.orm.exc.UnmappedClassError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">UnmappedClassError</span></code></a> if no mapping is configured
on the given class, or <a class="reference internal" href="../core/exceptions.html#sqlalchemy.exc.ArgumentError" title="sqlalchemy.exc.ArgumentError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ArgumentError</span></code></a> if a non-class
object is passed.</p>
<p>Equivalent functionality is available via the <a class="reference internal" href="../core/inspection.html#sqlalchemy.inspection.inspect" title="sqlalchemy.inspection.inspect"><code class="xref py py-func docutils literal notranslate"><span class="pre">inspect()</span></code></a>
function as:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">inspect</span><span class="p">(</span><span class="n">some_mapped_class</span><span class="p">)</span></pre></div>
</div>
<p>Using the inspection system will raise
<a class="reference internal" href="../core/exceptions.html#sqlalchemy.exc.NoInspectionAvailable" title="sqlalchemy.exc.NoInspectionAvailable"><code class="xref py py-class docutils literal notranslate"><span class="pre">sqlalchemy.exc.NoInspectionAvailable</span></code></a> if the class is not mapped.</p>
</dd></dl>
<dl class="function">
<dt id="sqlalchemy.orm.configure_mappers">
<code class="descclassname">sqlalchemy.orm.</code><code class="descname">configure_mappers</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.configure_mappers" title="Permalink to this definition">¶</a></dt>
<dd><p>Initialize the inter-mapper relationships of all mappers that
have been constructed thus far.</p>
<p>This function can be called any number of times, but in
most cases is invoked automatically, the first time mappings are used,
as well as whenever mappings are used and additional not-yet-configured
mappers have been constructed.</p>
<p>Points at which this occur include when a mapped class is instantiated
into an instance, as well as when the <a class="reference internal" href="session_api.html#sqlalchemy.orm.session.Session.query" title="sqlalchemy.orm.session.Session.query"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Session.query()</span></code></a> method
is used.</p>
<p>The <a class="reference internal" href="#sqlalchemy.orm.configure_mappers" title="sqlalchemy.orm.configure_mappers"><code class="xref py py-func docutils literal notranslate"><span class="pre">configure_mappers()</span></code></a> function provides several event hooks
that can be used to augment its functionality. These methods include:</p>
<ul class="simple">
<li><p><a class="reference internal" href="events.html#sqlalchemy.orm.events.MapperEvents.before_configured" title="sqlalchemy.orm.events.MapperEvents.before_configured"><code class="xref py py-meth docutils literal notranslate"><span class="pre">MapperEvents.before_configured()</span></code></a> - called once before
<a class="reference internal" href="#sqlalchemy.orm.configure_mappers" title="sqlalchemy.orm.configure_mappers"><code class="xref py py-func docutils literal notranslate"><span class="pre">configure_mappers()</span></code></a> does any work; this can be used to establish
additional options, properties, or related mappings before the operation
proceeds.</p></li>
<li><p><a class="reference internal" href="events.html#sqlalchemy.orm.events.MapperEvents.mapper_configured" title="sqlalchemy.orm.events.MapperEvents.mapper_configured"><code class="xref py py-meth docutils literal notranslate"><span class="pre">MapperEvents.mapper_configured()</span></code></a> - called as each individual
<a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> is configured within the process; will include all
mapper state except for backrefs set up by other mappers that are still
to be configured.</p></li>
<li><p><a class="reference internal" href="events.html#sqlalchemy.orm.events.MapperEvents.after_configured" title="sqlalchemy.orm.events.MapperEvents.after_configured"><code class="xref py py-meth docutils literal notranslate"><span class="pre">MapperEvents.after_configured()</span></code></a> - called once after
<a class="reference internal" href="#sqlalchemy.orm.configure_mappers" title="sqlalchemy.orm.configure_mappers"><code class="xref py py-func docutils literal notranslate"><span class="pre">configure_mappers()</span></code></a> is complete; at this stage, all
<a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> objects that are known to SQLAlchemy will be fully
configured. Note that the calling application may still have other
mappings that haven’t been produced yet, such as if they are in modules
as yet unimported.</p></li>
</ul>
</dd></dl>
<dl class="function">
<dt id="sqlalchemy.orm.clear_mappers">
<code class="descclassname">sqlalchemy.orm.</code><code class="descname">clear_mappers</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.clear_mappers" title="Permalink to this definition">¶</a></dt>
<dd><p>Remove all mappers from all classes.</p>
<p>This function removes all instrumentation from classes and disposes
of their associated mappers. Once called, the classes are unmapped
and can be later re-mapped with new mappers.</p>
<p><a class="reference internal" href="#sqlalchemy.orm.clear_mappers" title="sqlalchemy.orm.clear_mappers"><code class="xref py py-func docutils literal notranslate"><span class="pre">clear_mappers()</span></code></a> is <em>not</em> for normal use, as there is literally no
valid usage for it outside of very specific testing scenarios. Normally,
mappers are permanent structural components of user-defined classes, and
are never discarded independently of their class. If a mapped class
itself is garbage collected, its mapper is automatically disposed of as
well. As such, <a class="reference internal" href="#sqlalchemy.orm.clear_mappers" title="sqlalchemy.orm.clear_mappers"><code class="xref py py-func docutils literal notranslate"><span class="pre">clear_mappers()</span></code></a> is only for usage in test suites
that re-use the same classes with different mappings, which is itself an
extremely rare use case - the only such use case is in fact SQLAlchemy’s
own test suite, and possibly the test suites of other ORM extension
libraries which intend to test various combinations of mapper construction
upon a fixed set of classes.</p>
</dd></dl>
<dl class="function">
<dt id="sqlalchemy.orm.util.identity_key">
<code class="descclassname">sqlalchemy.orm.util.</code><code class="descname">identity_key</code><span class="sig-paren">(</span><em>*args</em>, <em>**kwargs</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.util.identity_key" title="Permalink to this definition">¶</a></dt>
<dd><p>Generate “identity key” tuples, as are used as keys in the
<a class="reference internal" href="session_api.html#sqlalchemy.orm.session.Session.identity_map" title="sqlalchemy.orm.session.Session.identity_map"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Session.identity_map</span></code></a> dictionary.</p>
<p>This function has several call styles:</p>
<ul>
<li><p><code class="docutils literal notranslate"><span class="pre">identity_key(class,</span> <span class="pre">ident,</span> <span class="pre">identity_token=token)</span></code></p>
<p>This form receives a mapped class and a primary key scalar or
tuple as an argument.</p>
<p>E.g.:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">identity_key</span><span class="p">(</span><span class="n">MyClass</span><span class="p">,</span> <span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">))</span>
<span class="go">(<class '__main__.MyClass'>, (1, 2), None)</span></pre></div>
</div>
<dl class="field-list">
<dt class="field-odd">param class</dt>
<dd class="field-odd"><p>mapped class (must be a positional argument)</p>
</dd>
<dt class="field-even">param ident</dt>
<dd class="field-even"><p>primary key, may be a scalar or tuple argument.</p>
</dd>
<dt class="field-odd">param identity_token</dt>
<dd class="field-odd"><p>optional identity token</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 1.2: </span>added identity_token</p>
</div>
</dd>
</dl>
</li>
<li><p><code class="docutils literal notranslate"><span class="pre">identity_key(instance=instance)</span></code></p>
<p>This form will produce the identity key for a given instance. The
instance need not be persistent, only that its primary key attributes
are populated (else the key will contain <code class="docutils literal notranslate"><span class="pre">None</span></code> for those missing
values).</p>
<p>E.g.:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">instance</span> <span class="o">=</span> <span class="n">MyClass</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">identity_key</span><span class="p">(</span><span class="n">instance</span><span class="o">=</span><span class="n">instance</span><span class="p">)</span>
<span class="go">(<class '__main__.MyClass'>, (1, 2), None)</span></pre></div>
</div>
<p>In this form, the given instance is ultimately run though
<a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.identity_key_from_instance" title="sqlalchemy.orm.mapper.Mapper.identity_key_from_instance"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Mapper.identity_key_from_instance()</span></code></a>, which will have the
effect of performing a database check for the corresponding row
if the object is expired.</p>
<dl class="field-list simple">
<dt class="field-odd">param instance</dt>
<dd class="field-odd"><p>object instance (must be given as a keyword arg)</p>
</dd>
</dl>
</li>
<li><p><code class="docutils literal notranslate"><span class="pre">identity_key(class,</span> <span class="pre">row=row,</span> <span class="pre">identity_token=token)</span></code></p>
<p>This form is similar to the class/tuple form, except is passed a
database result row as a <a class="reference internal" href="../core/connections.html#sqlalchemy.engine.RowProxy" title="sqlalchemy.engine.RowProxy"><code class="xref py py-class docutils literal notranslate"><span class="pre">RowProxy</span></code></a> object.</p>
<p>E.g.:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">row</span> <span class="o">=</span> <span class="n">engine</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s2">"select * from table where a=1 and b=2"</span><span class="p">)</span><span class="o">.</span><span class="n">first</span><span class="p">()</span>
<span class="gp">>>> </span><span class="n">identity_key</span><span class="p">(</span><span class="n">MyClass</span><span class="p">,</span> <span class="n">row</span><span class="o">=</span><span class="n">row</span><span class="p">)</span>
<span class="go">(<class '__main__.MyClass'>, (1, 2), None)</span></pre></div>
</div>
<dl class="field-list">
<dt class="field-odd">param class</dt>
<dd class="field-odd"><p>mapped class (must be a positional argument)</p>
</dd>
<dt class="field-even">param row</dt>
<dd class="field-even"><p><a class="reference internal" href="../core/connections.html#sqlalchemy.engine.RowProxy" title="sqlalchemy.engine.RowProxy"><code class="xref py py-class docutils literal notranslate"><span class="pre">RowProxy</span></code></a> row returned by a <a class="reference internal" href="../core/connections.html#sqlalchemy.engine.ResultProxy" title="sqlalchemy.engine.ResultProxy"><code class="xref py py-class docutils literal notranslate"><span class="pre">ResultProxy</span></code></a>
(must be given as a keyword arg)</p>
</dd>
<dt class="field-odd">param identity_token</dt>
<dd class="field-odd"><p>optional identity token</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 1.2: </span>added identity_token</p>
</div>
</dd>
</dl>
</li>
</ul>
</dd></dl>
<dl class="function">
<dt id="sqlalchemy.orm.util.polymorphic_union">
<code class="descclassname">sqlalchemy.orm.util.</code><code class="descname">polymorphic_union</code><span class="sig-paren">(</span><em>table_map</em>, <em>typecolname</em>, <em>aliasname='p_union'</em>, <em>cast_nulls=True</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.util.polymorphic_union" title="Permalink to this definition">¶</a></dt>
<dd><p>Create a <code class="docutils literal notranslate"><span class="pre">UNION</span></code> statement used by a polymorphic mapper.</p>
<p>See <a class="reference internal" href="inheritance.html#concrete-inheritance"><span class="std std-ref">Concrete Table Inheritance</span></a> for an example of how
this is used.</p>
<dl class="field-list simple">
<dt class="field-odd">Parameters</dt>
<dd class="field-odd"><ul class="simple">
<li><p><span class="target" id="sqlalchemy.orm.util.polymorphic_union.params.table_map"></span><strong>table_map</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.util.polymorphic_union.params.table_map">¶</a> – mapping of polymorphic identities to
<a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><code class="xref py py-class docutils literal notranslate"><span class="pre">Table</span></code></a> objects.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.util.polymorphic_union.params.typecolname"></span><strong>typecolname</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.util.polymorphic_union.params.typecolname">¶</a> – string name of a “discriminator” column, which will be
derived from the query, producing the polymorphic identity for
each row. If <code class="docutils literal notranslate"><span class="pre">None</span></code>, no polymorphic discriminator is generated.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.util.polymorphic_union.params.aliasname"></span><strong>aliasname</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.util.polymorphic_union.params.aliasname">¶</a> – name of the <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.alias" title="sqlalchemy.sql.expression.alias"><code class="xref py py-func docutils literal notranslate"><span class="pre">alias()</span></code></a>
construct generated.</p></li>
<li><p><span class="target" id="sqlalchemy.orm.util.polymorphic_union.params.cast_nulls"></span><strong>cast_nulls</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.util.polymorphic_union.params.cast_nulls">¶</a> – if True, non-existent columns, which are represented
as labeled NULLs, will be passed into CAST. This is a legacy behavior
that is problematic on some backends such as Oracle - in which case it
can be set to False.</p></li>
</ul>
</dd>
</dl>
</dd></dl>
<dl class="class">
<dt id="sqlalchemy.orm.mapper.Mapper">
<em class="property">class </em><code class="descclassname">sqlalchemy.orm.mapper.</code><code class="descname">Mapper</code><span class="sig-paren">(</span><em>class_</em>, <em>local_table=None</em>, <em>properties=None</em>, <em>primary_key=None</em>, <em>non_primary=False</em>, <em>inherits=None</em>, <em>inherit_condition=None</em>, <em>inherit_foreign_keys=None</em>, <em>extension=None</em>, <em>order_by=False</em>, <em>always_refresh=False</em>, <em>version_id_col=None</em>, <em>version_id_generator=None</em>, <em>polymorphic_on=None</em>, <em>_polymorphic_map=None</em>, <em>polymorphic_identity=None</em>, <em>concrete=False</em>, <em>with_polymorphic=None</em>, <em>polymorphic_load=None</em>, <em>allow_partial_pks=True</em>, <em>batch=True</em>, <em>column_prefix=None</em>, <em>include_properties=None</em>, <em>exclude_properties=None</em>, <em>passive_updates=True</em>, <em>passive_deletes=False</em>, <em>confirm_deleted_rows=True</em>, <em>eager_defaults=False</em>, <em>legacy_is_orphan=False</em>, <em>_compiled_cache_size=100</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper" title="Permalink to this definition">¶</a></dt>
<dd><p>Bases: <a class="reference internal" href="internals.html#sqlalchemy.orm.base.InspectionAttr" title="sqlalchemy.orm.base.InspectionAttr"><code class="xref py py-class docutils literal notranslate"><span class="pre">sqlalchemy.orm.base.InspectionAttr</span></code></a></p>
<p>Define the correlation of class attributes to database table
columns.</p>
<p>The <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> object is instantiated using the
<a class="reference internal" href="#sqlalchemy.orm.mapper" title="sqlalchemy.orm.mapper"><code class="xref py py-func docutils literal notranslate"><span class="pre">mapper()</span></code></a> function. For information
about instantiating new <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> objects, see
that function’s documentation.</p>
<p>When <a class="reference internal" href="#sqlalchemy.orm.mapper" title="sqlalchemy.orm.mapper"><code class="xref py py-func docutils literal notranslate"><span class="pre">mapper()</span></code></a> is used
explicitly to link a user defined class with table
metadata, this is referred to as <em>classical mapping</em>.
Modern SQLAlchemy usage tends to favor the
<a class="reference internal" href="extensions/declarative/api.html#module-sqlalchemy.ext.declarative" title="sqlalchemy.ext.declarative"><code class="xref py py-mod docutils literal notranslate"><span class="pre">sqlalchemy.ext.declarative</span></code></a> extension for class
configuration, which
makes usage of <a class="reference internal" href="#sqlalchemy.orm.mapper" title="sqlalchemy.orm.mapper"><code class="xref py py-func docutils literal notranslate"><span class="pre">mapper()</span></code></a> behind the scenes.</p>
<p>Given a particular class known to be mapped by the ORM,
the <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> which maintains it can be acquired
using the <a class="reference internal" href="../core/inspection.html#sqlalchemy.inspection.inspect" title="sqlalchemy.inspection.inspect"><code class="xref py py-func docutils literal notranslate"><span class="pre">inspect()</span></code></a> function:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">inspect</span>
<span class="n">mapper</span> <span class="o">=</span> <span class="n">inspect</span><span class="p">(</span><span class="n">MyClass</span><span class="p">)</span></pre></div>
</div>
<p>A class which was mapped by the <a class="reference internal" href="extensions/declarative/api.html#module-sqlalchemy.ext.declarative" title="sqlalchemy.ext.declarative"><code class="xref py py-mod docutils literal notranslate"><span class="pre">sqlalchemy.ext.declarative</span></code></a>
extension will also have its mapper available via the <code class="docutils literal notranslate"><span class="pre">__mapper__</span></code>
attribute.</p>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.__init__">
<code class="descname">__init__</code><span class="sig-paren">(</span><em>class_</em>, <em>local_table=None</em>, <em>properties=None</em>, <em>primary_key=None</em>, <em>non_primary=False</em>, <em>inherits=None</em>, <em>inherit_condition=None</em>, <em>inherit_foreign_keys=None</em>, <em>extension=None</em>, <em>order_by=False</em>, <em>always_refresh=False</em>, <em>version_id_col=None</em>, <em>version_id_generator=None</em>, <em>polymorphic_on=None</em>, <em>_polymorphic_map=None</em>, <em>polymorphic_identity=None</em>, <em>concrete=False</em>, <em>with_polymorphic=None</em>, <em>polymorphic_load=None</em>, <em>allow_partial_pks=True</em>, <em>batch=True</em>, <em>column_prefix=None</em>, <em>include_properties=None</em>, <em>exclude_properties=None</em>, <em>passive_updates=True</em>, <em>passive_deletes=False</em>, <em>confirm_deleted_rows=True</em>, <em>eager_defaults=False</em>, <em>legacy_is_orphan=False</em>, <em>_compiled_cache_size=100</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.__init__" title="Permalink to this definition">¶</a></dt>
<dd><p>Construct a new <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> object.</p>
<p>This constructor is mirrored as a public API function; see <a class="reference internal" href="#sqlalchemy.orm.mapper" title="sqlalchemy.orm.mapper"><code class="xref py py-func docutils literal notranslate"><span class="pre">mapper()</span></code></a> for a full usage and argument description.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.add_properties">
<code class="descname">add_properties</code><span class="sig-paren">(</span><em>dict_of_properties</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.add_properties" title="Permalink to this definition">¶</a></dt>
<dd><p>Add the given dictionary of properties to this mapper,
using <cite>add_property</cite>.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.add_property">
<code class="descname">add_property</code><span class="sig-paren">(</span><em>key</em>, <em>prop</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.add_property" title="Permalink to this definition">¶</a></dt>
<dd><p>Add an individual MapperProperty to this mapper.</p>
<p>If the mapper has not been configured yet, just adds the
property to the initial properties dictionary sent to the
constructor. If this Mapper has already been configured, then
the given MapperProperty is configured immediately.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.all_orm_descriptors">
<code class="descname">all_orm_descriptors</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.all_orm_descriptors" title="Permalink to this definition">¶</a></dt>
<dd><p>A namespace of all <a class="reference internal" href="internals.html#sqlalchemy.orm.base.InspectionAttr" title="sqlalchemy.orm.base.InspectionAttr"><code class="xref py py-class docutils literal notranslate"><span class="pre">InspectionAttr</span></code></a> attributes associated
with the mapped class.</p>
<p>These attributes are in all cases Python <a class="reference internal" href="../glossary.html#term-descriptors"><span class="xref std std-term">descriptors</span></a>
associated with the mapped class or its superclasses.</p>
<p>This namespace includes attributes that are mapped to the class
as well as attributes declared by extension modules.
It includes any Python descriptor type that inherits from
<a class="reference internal" href="internals.html#sqlalchemy.orm.base.InspectionAttr" title="sqlalchemy.orm.base.InspectionAttr"><code class="xref py py-class docutils literal notranslate"><span class="pre">InspectionAttr</span></code></a>. This includes
<a class="reference internal" href="internals.html#sqlalchemy.orm.attributes.QueryableAttribute" title="sqlalchemy.orm.attributes.QueryableAttribute"><code class="xref py py-class docutils literal notranslate"><span class="pre">QueryableAttribute</span></code></a>, as well as extension types such as
<a class="reference internal" href="extensions/hybrid.html#sqlalchemy.ext.hybrid.hybrid_property" title="sqlalchemy.ext.hybrid.hybrid_property"><code class="xref py py-class docutils literal notranslate"><span class="pre">hybrid_property</span></code></a>, <a class="reference internal" href="extensions/hybrid.html#sqlalchemy.ext.hybrid.hybrid_method" title="sqlalchemy.ext.hybrid.hybrid_method"><code class="xref py py-class docutils literal notranslate"><span class="pre">hybrid_method</span></code></a> and
<a class="reference internal" href="extensions/associationproxy.html#sqlalchemy.ext.associationproxy.AssociationProxy" title="sqlalchemy.ext.associationproxy.AssociationProxy"><code class="xref py py-class docutils literal notranslate"><span class="pre">AssociationProxy</span></code></a>.</p>
<p>To distinguish between mapped attributes and extension attributes,
the attribute <a class="reference internal" href="internals.html#sqlalchemy.orm.base.InspectionAttr.extension_type" title="sqlalchemy.orm.base.InspectionAttr.extension_type"><code class="xref py py-attr docutils literal notranslate"><span class="pre">InspectionAttr.extension_type</span></code></a> will refer
to a constant that distinguishes between different extension types.</p>
<p>When dealing with a <a class="reference internal" href="internals.html#sqlalchemy.orm.attributes.QueryableAttribute" title="sqlalchemy.orm.attributes.QueryableAttribute"><code class="xref py py-class docutils literal notranslate"><span class="pre">QueryableAttribute</span></code></a>, the
<a class="reference internal" href="internals.html#sqlalchemy.orm.attributes.QueryableAttribute.property" title="sqlalchemy.orm.attributes.QueryableAttribute.property"><code class="xref py py-attr docutils literal notranslate"><span class="pre">QueryableAttribute.property</span></code></a> attribute refers to the
<a class="reference internal" href="internals.html#sqlalchemy.orm.interfaces.MapperProperty" title="sqlalchemy.orm.interfaces.MapperProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperProperty</span></code></a> property, which is what you get when
referring to the collection of mapped properties via
<a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.attrs" title="sqlalchemy.orm.mapper.Mapper.attrs"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Mapper.attrs</span></code></a>.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.all_orm_descriptors" title="sqlalchemy.orm.mapper.Mapper.all_orm_descriptors"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Mapper.all_orm_descriptors</span></code></a> accessor namespace is an
instance of <code class="xref py py-class docutils literal notranslate"><span class="pre">OrderedProperties</span></code>. This is
a dictionary-like object which includes a small number of
named methods such as <code class="xref py py-meth docutils literal notranslate"><span class="pre">OrderedProperties.items()</span></code>
and <code class="xref py py-meth docutils literal notranslate"><span class="pre">OrderedProperties.values()</span></code>. When
accessing attributes dynamically, favor using the dict-access
scheme, e.g. <code class="docutils literal notranslate"><span class="pre">mapper.all_orm_descriptors[somename]</span></code> over
<code class="docutils literal notranslate"><span class="pre">getattr(mapper.all_orm_descriptors,</span> <span class="pre">somename)</span></code> to avoid name
collisions.</p>
</div>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.attrs" title="sqlalchemy.orm.mapper.Mapper.attrs"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Mapper.attrs</span></code></a></p>
</div>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.attrs">
<code class="descname">attrs</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.attrs" title="Permalink to this definition">¶</a></dt>
<dd><p>A namespace of all <a class="reference internal" href="internals.html#sqlalchemy.orm.interfaces.MapperProperty" title="sqlalchemy.orm.interfaces.MapperProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperProperty</span></code></a> objects
associated this mapper.</p>
<p>This is an object that provides each property based on
its key name. For instance, the mapper for a
<code class="docutils literal notranslate"><span class="pre">User</span></code> class which has <code class="docutils literal notranslate"><span class="pre">User.name</span></code> attribute would
provide <code class="docutils literal notranslate"><span class="pre">mapper.attrs.name</span></code>, which would be the
<a class="reference internal" href="internals.html#sqlalchemy.orm.properties.ColumnProperty" title="sqlalchemy.orm.properties.ColumnProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">ColumnProperty</span></code></a> representing the <code class="docutils literal notranslate"><span class="pre">name</span></code>
column. The namespace object can also be iterated,
which would yield each <a class="reference internal" href="internals.html#sqlalchemy.orm.interfaces.MapperProperty" title="sqlalchemy.orm.interfaces.MapperProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperProperty</span></code></a>.</p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> has several pre-filtered views
of this attribute which limit the types of properties
returned, including <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.synonyms" title="sqlalchemy.orm.mapper.Mapper.synonyms"><code class="xref py py-attr docutils literal notranslate"><span class="pre">synonyms</span></code></a>, <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.column_attrs" title="sqlalchemy.orm.mapper.Mapper.column_attrs"><code class="xref py py-attr docutils literal notranslate"><span class="pre">column_attrs</span></code></a>,
<a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.relationships" title="sqlalchemy.orm.mapper.Mapper.relationships"><code class="xref py py-attr docutils literal notranslate"><span class="pre">relationships</span></code></a>, and <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.composites" title="sqlalchemy.orm.mapper.Mapper.composites"><code class="xref py py-attr docutils literal notranslate"><span class="pre">composites</span></code></a>.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.attrs" title="sqlalchemy.orm.mapper.Mapper.attrs"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Mapper.attrs</span></code></a> accessor namespace is an
instance of <code class="xref py py-class docutils literal notranslate"><span class="pre">OrderedProperties</span></code>. This is
a dictionary-like object which includes a small number of
named methods such as <code class="xref py py-meth docutils literal notranslate"><span class="pre">OrderedProperties.items()</span></code>
and <code class="xref py py-meth docutils literal notranslate"><span class="pre">OrderedProperties.values()</span></code>. When
accessing attributes dynamically, favor using the dict-access
scheme, e.g. <code class="docutils literal notranslate"><span class="pre">mapper.attrs[somename]</span></code> over
<code class="docutils literal notranslate"><span class="pre">getattr(mapper.attrs,</span> <span class="pre">somename)</span></code> to avoid name collisions.</p>
</div>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.all_orm_descriptors" title="sqlalchemy.orm.mapper.Mapper.all_orm_descriptors"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Mapper.all_orm_descriptors</span></code></a></p>
</div>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.base_mapper">
<code class="descname">base_mapper</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.base_mapper" title="Permalink to this definition">¶</a></dt>
<dd><p>The base-most <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> in an inheritance chain.</p>
<p>In a non-inheriting scenario, this attribute will always be this
<a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>. In an inheritance scenario, it references
the <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> which is parent to all other <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>
objects in the inheritance chain.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.c">
<code class="descname">c</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.c" title="Permalink to this definition">¶</a></dt>
<dd><p>A synonym for <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.columns" title="sqlalchemy.orm.mapper.Mapper.columns"><code class="xref py py-attr docutils literal notranslate"><span class="pre">columns</span></code></a>.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.cascade_iterator">
<code class="descname">cascade_iterator</code><span class="sig-paren">(</span><em>type_</em>, <em>state</em>, <em>halt_on=None</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.cascade_iterator" title="Permalink to this definition">¶</a></dt>
<dd><p>Iterate each element and its mapper in an object graph,
for all relationships that meet the given cascade rule.</p>
<dl class="field-list simple">
<dt class="field-odd">Parameters</dt>
<dd class="field-odd"><ul class="simple">
<li><p><span class="target" id="sqlalchemy.orm.mapper.Mapper.cascade_iterator.params.type_"></span><strong>type_</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.Mapper.cascade_iterator.params.type_">¶</a> – <p>The name of the cascade rule (i.e. <code class="docutils literal notranslate"><span class="pre">"save-update"</span></code>, <code class="docutils literal notranslate"><span class="pre">"delete"</span></code>,
etc.).</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>the <code class="docutils literal notranslate"><span class="pre">"all"</span></code> cascade is not accepted here. For a generic
object traversal function, see <a class="reference internal" href="../faq/sessions.html#faq-walk-objects"><span class="std std-ref">How do I walk all objects that are related to a given object?</span></a>.</p>
</div>
</p></li>
<li><p><span class="target" id="sqlalchemy.orm.mapper.Mapper.cascade_iterator.params.state"></span><strong>state</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.Mapper.cascade_iterator.params.state">¶</a> – The lead InstanceState. child items will be processed per
the relationships defined for this object’s mapper.</p></li>
</ul>
</dd>
<dt class="field-even">Returns</dt>
<dd class="field-even"><p>the method yields individual object instances.</p>
</dd>
</dl>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="cascades.html#unitofwork-cascades"><span class="std std-ref">Cascades</span></a></p>
<p><a class="reference internal" href="../faq/sessions.html#faq-walk-objects"><span class="std std-ref">How do I walk all objects that are related to a given object?</span></a> - illustrates a generic function to
traverse all objects without relying on cascades.</p>
</div>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.class_">
<code class="descname">class_</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.class_" title="Permalink to this definition">¶</a></dt>
<dd><p>The Python class which this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> maps.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.class_manager">
<code class="descname">class_manager</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.class_manager" title="Permalink to this definition">¶</a></dt>
<dd><p>The <a class="reference internal" href="internals.html#sqlalchemy.orm.instrumentation.ClassManager" title="sqlalchemy.orm.instrumentation.ClassManager"><code class="xref py py-class docutils literal notranslate"><span class="pre">ClassManager</span></code></a> which maintains event listeners
and class-bound descriptors for this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.column_attrs">
<code class="descname">column_attrs</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.column_attrs" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a namespace of all <a class="reference internal" href="internals.html#sqlalchemy.orm.properties.ColumnProperty" title="sqlalchemy.orm.properties.ColumnProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">ColumnProperty</span></code></a>
properties maintained by this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.attrs" title="sqlalchemy.orm.mapper.Mapper.attrs"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Mapper.attrs</span></code></a> - namespace of all <a class="reference internal" href="internals.html#sqlalchemy.orm.interfaces.MapperProperty" title="sqlalchemy.orm.interfaces.MapperProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperProperty</span></code></a>
objects.</p>
</div>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.columns">
<code class="descname">columns</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.columns" title="Permalink to this definition">¶</a></dt>
<dd><p>A collection of <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a> or other scalar expression
objects maintained by this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>.</p>
<p>The collection behaves the same as that of the <code class="docutils literal notranslate"><span class="pre">c</span></code> attribute on
any <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><code class="xref py py-class docutils literal notranslate"><span class="pre">Table</span></code></a> object, except that only those columns included in
this mapping are present, and are keyed based on the attribute name
defined in the mapping, not necessarily the <code class="docutils literal notranslate"><span class="pre">key</span></code> attribute of the
<a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a> itself. Additionally, scalar expressions mapped
by <a class="reference internal" href="mapping_columns.html#sqlalchemy.orm.column_property" title="sqlalchemy.orm.column_property"><code class="xref py py-func docutils literal notranslate"><span class="pre">column_property()</span></code></a> are also present here.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.common_parent">
<code class="descname">common_parent</code><span class="sig-paren">(</span><em>other</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.common_parent" title="Permalink to this definition">¶</a></dt>
<dd><p>Return true if the given mapper shares a
common inherited parent as this mapper.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.composites">
<code class="descname">composites</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.composites" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a namespace of all <a class="reference internal" href="internals.html#sqlalchemy.orm.descriptor_props.CompositeProperty" title="sqlalchemy.orm.descriptor_props.CompositeProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">CompositeProperty</span></code></a>
properties maintained by this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.attrs" title="sqlalchemy.orm.mapper.Mapper.attrs"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Mapper.attrs</span></code></a> - namespace of all <a class="reference internal" href="internals.html#sqlalchemy.orm.interfaces.MapperProperty" title="sqlalchemy.orm.interfaces.MapperProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperProperty</span></code></a>
objects.</p>
</div>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.concrete">
<code class="descname">concrete</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.concrete" title="Permalink to this definition">¶</a></dt>
<dd><p>Represent <code class="docutils literal notranslate"><span class="pre">True</span></code> if this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> is a concrete
inheritance mapper.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.configured">
<code class="descname">configured</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.configured" title="Permalink to this definition">¶</a></dt>
<dd><p>Represent <code class="docutils literal notranslate"><span class="pre">True</span></code> if this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> has been configured.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="#sqlalchemy.orm.configure_mappers" title="sqlalchemy.orm.configure_mappers"><code class="xref py py-func docutils literal notranslate"><span class="pre">configure_mappers()</span></code></a>.</p>
</div>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.entity">
<code class="descname">entity</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.entity" title="Permalink to this definition">¶</a></dt>
<dd><p>Part of the inspection API.</p>
<p>Returns self.class_.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.get_property">
<code class="descname">get_property</code><span class="sig-paren">(</span><em>key</em>, <em>_configure_mappers=True</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.get_property" title="Permalink to this definition">¶</a></dt>
<dd><p>return a MapperProperty associated with the given key.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.get_property_by_column">
<code class="descname">get_property_by_column</code><span class="sig-paren">(</span><em>column</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.get_property_by_column" title="Permalink to this definition">¶</a></dt>
<dd><p>Given a <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a> object, return the
<a class="reference internal" href="internals.html#sqlalchemy.orm.interfaces.MapperProperty" title="sqlalchemy.orm.interfaces.MapperProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperProperty</span></code></a> which maps this column.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.identity_key_from_instance">
<code class="descname">identity_key_from_instance</code><span class="sig-paren">(</span><em>instance</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.identity_key_from_instance" title="Permalink to this definition">¶</a></dt>
<dd><p>Return the identity key for the given instance, based on
its primary key attributes.</p>
<p>If the instance’s state is expired, calling this method
will result in a database check to see if the object has been deleted.
If the row no longer exists,
<a class="reference internal" href="exceptions.html#sqlalchemy.orm.exc.ObjectDeletedError" title="sqlalchemy.orm.exc.ObjectDeletedError"><code class="xref py py-class docutils literal notranslate"><span class="pre">ObjectDeletedError</span></code></a> is raised.</p>
<p>This value is typically also found on the instance state under the
attribute name <cite>key</cite>.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.identity_key_from_primary_key">
<code class="descname">identity_key_from_primary_key</code><span class="sig-paren">(</span><em>primary_key</em>, <em>identity_token=None</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.identity_key_from_primary_key" title="Permalink to this definition">¶</a></dt>
<dd><p>Return an identity-map key for use in storing/retrieving an
item from an identity map.</p>
<dl class="field-list simple">
<dt class="field-odd">Parameters</dt>
<dd class="field-odd"><p><span class="target" id="sqlalchemy.orm.mapper.Mapper.identity_key_from_primary_key.params.primary_key"></span><strong>primary_key</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.Mapper.identity_key_from_primary_key.params.primary_key">¶</a> – A list of values indicating the identifier.</p>
</dd>
</dl>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.identity_key_from_row">
<code class="descname">identity_key_from_row</code><span class="sig-paren">(</span><em>row</em>, <em>identity_token=None</em>, <em>adapter=None</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.identity_key_from_row" title="Permalink to this definition">¶</a></dt>
<dd><p>Return an identity-map key for use in storing/retrieving an
item from the identity map.</p>
<dl class="field-list simple">
<dt class="field-odd">Parameters</dt>
<dd class="field-odd"><p><span class="target" id="sqlalchemy.orm.mapper.Mapper.identity_key_from_row.params.row"></span><strong>row</strong><a class="paramlink headerlink reference internal" href="#sqlalchemy.orm.mapper.Mapper.identity_key_from_row.params.row">¶</a> – A <a class="reference internal" href="../core/connections.html#sqlalchemy.engine.RowProxy" title="sqlalchemy.engine.RowProxy"><code class="xref py py-class docutils literal notranslate"><span class="pre">RowProxy</span></code></a> instance. The columns which are
mapped by this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> should be locatable in the row,
preferably via the <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a> object directly (as is the case
when a <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.select" title="sqlalchemy.sql.expression.select"><code class="xref py py-func docutils literal notranslate"><span class="pre">select()</span></code></a> construct is executed), or via string names of
the form <code class="docutils literal notranslate"><span class="pre"><tablename>_<colname></span></code>.</p>
</dd>
</dl>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.inherits">
<code class="descname">inherits</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.inherits" title="Permalink to this definition">¶</a></dt>
<dd><p>References the <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> which this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>
inherits from, if any.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.is_mapper">
<code class="descname">is_mapper</code><em class="property"> = True</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.is_mapper" title="Permalink to this definition">¶</a></dt>
<dd><p>Part of the inspection API.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.isa">
<code class="descname">isa</code><span class="sig-paren">(</span><em>other</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.isa" title="Permalink to this definition">¶</a></dt>
<dd><p>Return True if the this mapper inherits from the given mapper.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.iterate_properties">
<code class="descname">iterate_properties</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.iterate_properties" title="Permalink to this definition">¶</a></dt>
<dd><p>return an iterator of all MapperProperty objects.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.local_table">
<code class="descname">local_table</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.local_table" title="Permalink to this definition">¶</a></dt>
<dd><p>The <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.Selectable" title="sqlalchemy.sql.expression.Selectable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Selectable</span></code></a> which this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> manages.</p>
<p>Typically is an instance of <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><code class="xref py py-class docutils literal notranslate"><span class="pre">Table</span></code></a> or <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.Alias" title="sqlalchemy.sql.expression.Alias"><code class="xref py py-class docutils literal notranslate"><span class="pre">Alias</span></code></a>.
May also be <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p>
<p>The “local” table is the
selectable that the <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> is directly responsible for
managing from an attribute access and flush perspective. For
non-inheriting mappers, the local table is the same as the
“mapped” table. For joined-table inheritance mappers, local_table
will be the particular sub-table of the overall “join” which
this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> represents. If this mapper is a
single-table inheriting mapper, local_table will be <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.mapped_table" title="sqlalchemy.orm.mapper.Mapper.mapped_table"><code class="xref py py-attr docutils literal notranslate"><span class="pre">mapped_table</span></code></a>.</p>
</div>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.mapped_table">
<code class="descname">mapped_table</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.mapped_table" title="Permalink to this definition">¶</a></dt>
<dd><p>The <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.Selectable" title="sqlalchemy.sql.expression.Selectable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Selectable</span></code></a> to which this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> is mapped.</p>
<p>Typically an instance of <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><code class="xref py py-class docutils literal notranslate"><span class="pre">Table</span></code></a>, <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.Join" title="sqlalchemy.sql.expression.Join"><code class="xref py py-class docutils literal notranslate"><span class="pre">Join</span></code></a>, or
<a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.Alias" title="sqlalchemy.sql.expression.Alias"><code class="xref py py-class docutils literal notranslate"><span class="pre">Alias</span></code></a>.</p>
<p>The “mapped” table is the selectable that
the mapper selects from during queries. For non-inheriting
mappers, the mapped table is the same as the “local” table.
For joined-table inheritance mappers, mapped_table references the
full <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.Join" title="sqlalchemy.sql.expression.Join"><code class="xref py py-class docutils literal notranslate"><span class="pre">Join</span></code></a> representing full rows for this particular
subclass. For single-table inheritance mappers, mapped_table
references the base table.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.local_table" title="sqlalchemy.orm.mapper.Mapper.local_table"><code class="xref py py-attr docutils literal notranslate"><span class="pre">local_table</span></code></a>.</p>
</div>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.mapper">
<code class="descname">mapper</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.mapper" title="Permalink to this definition">¶</a></dt>
<dd><p>Part of the inspection API.</p>
<p>Returns self.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.non_primary">
<code class="descname">non_primary</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.non_primary" title="Permalink to this definition">¶</a></dt>
<dd><p>Represent <code class="docutils literal notranslate"><span class="pre">True</span></code> if this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> is a “non-primary”
mapper, e.g. a mapper that is used only to select rows but not for
persistence management.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.polymorphic_identity">
<code class="descname">polymorphic_identity</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.polymorphic_identity" title="Permalink to this definition">¶</a></dt>
<dd><p>Represent an identifier which is matched against the
<a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.polymorphic_on" title="sqlalchemy.orm.mapper.Mapper.polymorphic_on"><code class="xref py py-attr docutils literal notranslate"><span class="pre">polymorphic_on</span></code></a> column during result row loading.</p>
<p>Used only with inheritance, this object can be of any type which is
comparable to the type of column represented by
<a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.polymorphic_on" title="sqlalchemy.orm.mapper.Mapper.polymorphic_on"><code class="xref py py-attr docutils literal notranslate"><span class="pre">polymorphic_on</span></code></a>.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.polymorphic_iterator">
<code class="descname">polymorphic_iterator</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.polymorphic_iterator" title="Permalink to this definition">¶</a></dt>
<dd><p>Iterate through the collection including this mapper and
all descendant mappers.</p>
<p>This includes not just the immediately inheriting mappers but
all their inheriting mappers as well.</p>
<p>To iterate through an entire hierarchy, use
<code class="docutils literal notranslate"><span class="pre">mapper.base_mapper.polymorphic_iterator()</span></code>.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.polymorphic_map">
<code class="descname">polymorphic_map</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.polymorphic_map" title="Permalink to this definition">¶</a></dt>
<dd><p>A mapping of “polymorphic identity” identifiers mapped to
<a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> instances, within an inheritance scenario.</p>
<p>The identifiers can be of any type which is comparable to the
type of column represented by <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.polymorphic_on" title="sqlalchemy.orm.mapper.Mapper.polymorphic_on"><code class="xref py py-attr docutils literal notranslate"><span class="pre">polymorphic_on</span></code></a>.</p>
<p>An inheritance chain of mappers will all reference the same
polymorphic map object. The object is used to correlate incoming
result rows to target mappers.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.polymorphic_on">
<code class="descname">polymorphic_on</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.polymorphic_on" title="Permalink to this definition">¶</a></dt>
<dd><p>The <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a> or SQL expression specified as the
<code class="docutils literal notranslate"><span class="pre">polymorphic_on</span></code> argument
for this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>, within an inheritance scenario.</p>
<p>This attribute is normally a <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a> instance but
may also be an expression, such as one derived from
<a class="reference internal" href="../core/sqlelement.html#sqlalchemy.sql.expression.cast" title="sqlalchemy.sql.expression.cast"><code class="xref py py-func docutils literal notranslate"><span class="pre">cast()</span></code></a>.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.primary_key">
<code class="descname">primary_key</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.primary_key" title="Permalink to this definition">¶</a></dt>
<dd><p>An iterable containing the collection of <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><code class="xref py py-class docutils literal notranslate"><span class="pre">Column</span></code></a> objects
which comprise the ‘primary key’ of the mapped table, from the
perspective of this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>.</p>
<p>This list is against the selectable in <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.mapped_table" title="sqlalchemy.orm.mapper.Mapper.mapped_table"><code class="xref py py-attr docutils literal notranslate"><span class="pre">mapped_table</span></code></a>. In
the case of inheriting mappers, some columns may be managed by a
superclass mapper. For example, in the case of a <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.Join" title="sqlalchemy.sql.expression.Join"><code class="xref py py-class docutils literal notranslate"><span class="pre">Join</span></code></a>, the
primary key is determined by all of the primary key columns across all
tables referenced by the <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.Join" title="sqlalchemy.sql.expression.Join"><code class="xref py py-class docutils literal notranslate"><span class="pre">Join</span></code></a>.</p>
<p>The list is also not necessarily the same as the primary key column
collection associated with the underlying tables; the <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>
features a <code class="docutils literal notranslate"><span class="pre">primary_key</span></code> argument that can override what the
<a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> considers as primary key columns.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.primary_key_from_instance">
<code class="descname">primary_key_from_instance</code><span class="sig-paren">(</span><em>instance</em><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.primary_key_from_instance" title="Permalink to this definition">¶</a></dt>
<dd><p>Return the list of primary key values for the given
instance.</p>
<p>If the instance’s state is expired, calling this method
will result in a database check to see if the object has been deleted.
If the row no longer exists,
<a class="reference internal" href="exceptions.html#sqlalchemy.orm.exc.ObjectDeletedError" title="sqlalchemy.orm.exc.ObjectDeletedError"><code class="xref py py-class docutils literal notranslate"><span class="pre">ObjectDeletedError</span></code></a> is raised.</p>
</dd></dl>
<dl class="method">
<dt id="sqlalchemy.orm.mapper.Mapper.primary_mapper">
<code class="descname">primary_mapper</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.primary_mapper" title="Permalink to this definition">¶</a></dt>
<dd><p>Return the primary mapper corresponding to this mapper’s class key
(class).</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.relationships">
<code class="descname">relationships</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.relationships" title="Permalink to this definition">¶</a></dt>
<dd><p>A namespace of all <a class="reference internal" href="internals.html#sqlalchemy.orm.properties.RelationshipProperty" title="sqlalchemy.orm.properties.RelationshipProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">RelationshipProperty</span></code></a> properties
maintained by this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>the <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.relationships" title="sqlalchemy.orm.mapper.Mapper.relationships"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Mapper.relationships</span></code></a> accessor namespace is an
instance of <code class="xref py py-class docutils literal notranslate"><span class="pre">OrderedProperties</span></code>. This is
a dictionary-like object which includes a small number of
named methods such as <code class="xref py py-meth docutils literal notranslate"><span class="pre">OrderedProperties.items()</span></code>
and <code class="xref py py-meth docutils literal notranslate"><span class="pre">OrderedProperties.values()</span></code>. When
accessing attributes dynamically, favor using the dict-access
scheme, e.g. <code class="docutils literal notranslate"><span class="pre">mapper.relationships[somename]</span></code> over
<code class="docutils literal notranslate"><span class="pre">getattr(mapper.relationships,</span> <span class="pre">somename)</span></code> to avoid name
collisions.</p>
</div>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.attrs" title="sqlalchemy.orm.mapper.Mapper.attrs"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Mapper.attrs</span></code></a> - namespace of all <a class="reference internal" href="internals.html#sqlalchemy.orm.interfaces.MapperProperty" title="sqlalchemy.orm.interfaces.MapperProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperProperty</span></code></a>
objects.</p>
</div>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.selectable">
<code class="descname">selectable</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.selectable" title="Permalink to this definition">¶</a></dt>
<dd><p>The <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.select" title="sqlalchemy.sql.expression.select"><code class="xref py py-func docutils literal notranslate"><span class="pre">select()</span></code></a> construct this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> selects from
by default.</p>
<p>Normally, this is equivalent to <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.mapped_table" title="sqlalchemy.orm.mapper.Mapper.mapped_table"><code class="xref py py-attr docutils literal notranslate"><span class="pre">mapped_table</span></code></a>, unless
the <code class="docutils literal notranslate"><span class="pre">with_polymorphic</span></code> feature is in use, in which case the
full “polymorphic” selectable is returned.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.self_and_descendants">
<code class="descname">self_and_descendants</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.self_and_descendants" title="Permalink to this definition">¶</a></dt>
<dd><p>The collection including this mapper and all descendant mappers.</p>
<p>This includes not just the immediately inheriting mappers but
all their inheriting mappers as well.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.single">
<code class="descname">single</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.single" title="Permalink to this definition">¶</a></dt>
<dd><p>Represent <code class="docutils literal notranslate"><span class="pre">True</span></code> if this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> is a single table
inheritance mapper.</p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.local_table" title="sqlalchemy.orm.mapper.Mapper.local_table"><code class="xref py py-attr docutils literal notranslate"><span class="pre">local_table</span></code></a> will be <code class="docutils literal notranslate"><span class="pre">None</span></code> if this flag is set.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.synonyms">
<code class="descname">synonyms</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.synonyms" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a namespace of all <a class="reference internal" href="internals.html#sqlalchemy.orm.descriptor_props.SynonymProperty" title="sqlalchemy.orm.descriptor_props.SynonymProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">SynonymProperty</span></code></a>
properties maintained by this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a>.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper.attrs" title="sqlalchemy.orm.mapper.Mapper.attrs"><code class="xref py py-attr docutils literal notranslate"><span class="pre">Mapper.attrs</span></code></a> - namespace of all <a class="reference internal" href="internals.html#sqlalchemy.orm.interfaces.MapperProperty" title="sqlalchemy.orm.interfaces.MapperProperty"><code class="xref py py-class docutils literal notranslate"><span class="pre">MapperProperty</span></code></a>
objects.</p>
</div>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.tables">
<code class="descname">tables</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.tables" title="Permalink to this definition">¶</a></dt>
<dd><p>An iterable containing the collection of <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><code class="xref py py-class docutils literal notranslate"><span class="pre">Table</span></code></a> objects
which this <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> is aware of.</p>
<p>If the mapper is mapped to a <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.Join" title="sqlalchemy.sql.expression.Join"><code class="xref py py-class docutils literal notranslate"><span class="pre">Join</span></code></a>, or an <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.Alias" title="sqlalchemy.sql.expression.Alias"><code class="xref py py-class docutils literal notranslate"><span class="pre">Alias</span></code></a>
representing a <a class="reference internal" href="../core/selectable.html#sqlalchemy.sql.expression.Select" title="sqlalchemy.sql.expression.Select"><code class="xref py py-class docutils literal notranslate"><span class="pre">Select</span></code></a>, the individual <a class="reference internal" href="../core/metadata.html#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><code class="xref py py-class docutils literal notranslate"><span class="pre">Table</span></code></a>
objects that comprise the full construct will be represented here.</p>
<p>This is a <em>read only</em> attribute determined during mapper construction.
Behavior is undefined if directly modified.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.validators">
<code class="descname">validators</code><em class="property"> = None</em><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.validators" title="Permalink to this definition">¶</a></dt>
<dd><p>An immutable dictionary of attributes which have been decorated
using the <a class="reference internal" href="mapped_attributes.html#sqlalchemy.orm.validates" title="sqlalchemy.orm.validates"><code class="xref py py-func docutils literal notranslate"><span class="pre">validates()</span></code></a> decorator.</p>
<p>The dictionary contains string attribute names as keys
mapped to the actual validation method.</p>
</dd></dl>
<dl class="attribute">
<dt id="sqlalchemy.orm.mapper.Mapper.with_polymorphic_mappers">
<code class="descname">with_polymorphic_mappers</code><a class="headerlink" href="#sqlalchemy.orm.mapper.Mapper.with_polymorphic_mappers" title="Permalink to this definition">¶</a></dt>
<dd><p>The list of <a class="reference internal" href="#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapper</span></code></a> objects included in the
default “polymorphic” query.</p>
</dd></dl>
</dd></dl>
</div>
</div>
</div>
<div id="docs-bottom-navigation" class="docs-navigation-links, withsidebar">
Previous:
<a href="versioning.html" title="previous chapter">Configuring a Version Counter</a>
Next:
<a href="relationships.html" title="next chapter">Relationship Configuration</a>
<div id="docs-copyright">
© <a href="../copyright.html">Copyright</a> 2007-2019, the SQLAlchemy authors and contributors.
Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 2.0.1.
</div>
</div>
</div>
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: '../',
VERSION: '1.2.19',
COLLAPSE_MODINDEX: false,
FILE_SUFFIX: '.html'
};
</script>
<script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script>
<!-- begin iterate through sphinx environment script_files -->
<script type="text/javascript" src="../_static/jquery.js"></script>
<script type="text/javascript" src="../_static/underscore.js"></script>
<script type="text/javascript" src="../_static/doctools.js"></script>
<script type="text/javascript" src="../_static/language_data.js"></script>
<!-- end iterate through sphinx environment script_files -->
<script type="text/javascript" src="../_static/detectmobile.js"></script>
<script type="text/javascript" src="../_static/init.js"></script>
</body>
</html>
distrib
>
Mageia
>
7
>
armv7hl
>
media
>
core-updates
>
by-pkgid
>
b0b6ffab06cbeede296e36ce94734bf8
>
files
>
853
