<!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" lang="">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Model _meta API — Django 1.8.19 documentation</title>
<link rel="stylesheet" href="../../_static/default.css" type="text/css" />
<link rel="stylesheet" href="../../_static/pygments.css" type="text/css" />
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: '../../',
VERSION: '1.8.19',
COLLAPSE_INDEX: false,
FILE_SUFFIX: '.html',
HAS_SOURCE: true
};
</script>
<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>
<link rel="index" title="Index" href="../../genindex.html" />
<link rel="search" title="Search" href="../../search.html" />
<link rel="top" title="Django 1.8.19 documentation" href="../../contents.html" />
<link rel="up" title="Models" href="index.html" />
<link rel="next" title="Related objects reference" href="relations.html" />
<link rel="prev" title="Model field reference" href="fields.html" />
<script type="text/javascript" src="../../templatebuiltins.js"></script>
<script type="text/javascript">
(function($) {
if (!django_template_builtins) {
// templatebuiltins.js missing, do nothing.
return;
}
$(document).ready(function() {
// Hyperlink Django template tags and filters
var base = "../templates/builtins.html";
if (base == "#") {
// Special case for builtins.html itself
base = "";
}
// Tags are keywords, class '.k'
$("div.highlight\\-html\\+django span.k").each(function(i, elem) {
var tagname = $(elem).text();
if ($.inArray(tagname, django_template_builtins.ttags) != -1) {
var fragment = tagname.replace(/_/, '-');
$(elem).html("<a href='" + base + "#" + fragment + "'>" + tagname + "</a>");
}
});
// Filters are functions, class '.nf'
$("div.highlight\\-html\\+django span.nf").each(function(i, elem) {
var filtername = $(elem).text();
if ($.inArray(filtername, django_template_builtins.tfilters) != -1) {
var fragment = filtername.replace(/_/, '-');
$(elem).html("<a href='" + base + "#" + fragment + "'>" + filtername + "</a>");
}
});
});
})(jQuery);
</script>
</head>
<body role="document">
<div class="document">
<div id="custom-doc" class="yui-t6">
<div id="hd">
<h1><a href="../../index.html">Django 1.8.19 documentation</a></h1>
<div id="global-nav">
<a title="Home page" href="../../index.html">Home</a> |
<a title="Table of contents" href="../../contents.html">Table of contents</a> |
<a title="Global index" href="../../genindex.html">Index</a> |
<a title="Module index" href="../../py-modindex.html">Modules</a>
</div>
<div class="nav">
« <a href="fields.html" title="Model field reference">previous</a>
|
<a href="../index.html" title="API Reference" accesskey="U">up</a>
|
<a href="relations.html" title="Related objects reference">next</a> »</div>
</div>
<div id="bd">
<div id="yui-main">
<div class="yui-b">
<div class="yui-g" id="ref-models-meta">
<div class="section" id="s-module-django.db.models.options">
<span id="s-model-meta-api"></span><span id="module-django.db.models.options"></span><span id="model-meta-api"></span><h1>Model <code class="docutils literal"><span class="pre">_meta</span></code> API<a class="headerlink" href="#module-django.db.models.options" title="Permalink to this headline">¶</a></h1>
<dl class="class">
<dt id="django.db.models.options.Options">
<em class="property">class </em><code class="descname">Options</code><a class="reference internal" href="../../_modules/django/db/models/options.html#Options"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.models.options.Options" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<p>The model <code class="docutils literal"><span class="pre">_meta</span></code> API is at the core of the Django ORM. It enables other
parts of the system such as lookups, queries, forms, and the admin to
understand the capabilities of each model. The API is accessible through
the <code class="docutils literal"><span class="pre">_meta</span></code> attribute of each model class, which is an instance of an
<code class="docutils literal"><span class="pre">django.db.models.options.Options</span></code> object.</p>
<p>Methods that it provides can be used to:</p>
<ul class="simple">
<li>Retrieve all field instances of a model</li>
<li>Retrieve a single field instance of a model by name</li>
</ul>
<div class="versionchanged">
<span class="title">Changed in Django 1.8:</span> <p>The Model <code class="docutils literal"><span class="pre">_meta</span></code> API has always existed as a Django internal, but
wasn’t formally documented and supported. As part of the effort to
make this API public, some of the already existing API entry points
have changed slightly. A <a class="reference internal" href="#migrating-old-meta-api"><span class="std std-ref">migration guide</span></a>
has been provided to assist in converting your code to use the new,
official API.</p>
</div>
<div class="section" id="s-field-access-api">
<span id="s-model-meta-field-api"></span><span id="field-access-api"></span><span id="model-meta-field-api"></span><h2>Field access API<a class="headerlink" href="#field-access-api" title="Permalink to this headline">¶</a></h2>
<div class="section" id="s-retrieving-a-single-field-instance-of-a-model-by-name">
<span id="retrieving-a-single-field-instance-of-a-model-by-name"></span><h3>Retrieving a single field instance of a model by name<a class="headerlink" href="#retrieving-a-single-field-instance-of-a-model-by-name" title="Permalink to this headline">¶</a></h3>
<dl class="method">
<dt id="django.db.models.options.Options.get_field">
<code class="descclassname">Options.</code><code class="descname">get_field</code>(<em>field_name</em>)<a class="reference internal" href="../../_modules/django/db/models/options.html#Options.get_field"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.models.options.Options.get_field" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns the field instance given a name of a field.</p>
<p><code class="docutils literal"><span class="pre">field_name</span></code> can be the name of a field on the model, a field
on an abstract or inherited model, or a field defined on another
model that points to the model. In the latter case, the <code class="docutils literal"><span class="pre">field_name</span></code>
will be the <code class="docutils literal"><span class="pre">related_name</span></code> defined by the user or the name automatically
generated by Django itself.</p>
<p><a class="reference internal" href="fields.html#django.db.models.Field.hidden" title="django.db.models.Field.hidden"><code class="xref py py-attr docutils literal"><span class="pre">Hidden</span> <span class="pre">fields</span></code></a> cannot be retrieved
by name.</p>
<p>If a field with the given name is not found a
<a class="reference internal" href="../exceptions.html#django.core.exceptions.FieldDoesNotExist" title="django.core.exceptions.FieldDoesNotExist"><code class="xref py py-class docutils literal"><span class="pre">FieldDoesNotExist</span></code></a> exception will be
raised.</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">from</span> <span class="nn">django.contrib.auth.models</span> <span class="kn">import</span> <span class="n">User</span>
<span class="go"># A field on the model</span>
<span class="gp">>>> </span><span class="n">User</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_field</span><span class="p">(</span><span class="s1">'username'</span><span class="p">)</span>
<span class="go"><django.db.models.fields.CharField: username></span>
<span class="go"># A field from another model that has a relation with the current model</span>
<span class="gp">>>> </span><span class="n">User</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_field</span><span class="p">(</span><span class="s1">'logentry'</span><span class="p">)</span>
<span class="go"><ManyToOneRel: admin.logentry></span>
<span class="go"># A non existent field</span>
<span class="gp">>>> </span><span class="n">User</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_field</span><span class="p">(</span><span class="s1">'does_not_exist'</span><span class="p">)</span>
<span class="gt">Traceback (most recent call last):</span>
<span class="o">...</span>
<span class="gr">FieldDoesNotExist</span>: <span class="n">User has no field named 'does_not_exist'</span>
</pre></div>
</div>
<div class="deprecated">
<p><span class="versionmodified">Deprecated since version 1.8: </span><a class="reference internal" href="#django.db.models.options.Options.get_field" title="django.db.models.options.Options.get_field"><code class="xref py py-meth docutils literal"><span class="pre">Options.get_field()</span></code></a> previously accepted a <code class="docutils literal"><span class="pre">many_to_many</span></code>
parameter which could be set to <code class="docutils literal"><span class="pre">False</span></code> to avoid searching
<code class="docutils literal"><span class="pre">ManyToManyField</span></code>s. The old behavior has been preserved for
backwards compatibility; however, the parameter and this behavior
has been deprecated.</p>
<p>If you wish to filter out <code class="docutils literal"><span class="pre">ManyToManyField</span></code>s, you can inspect the
<a class="reference internal" href="fields.html#django.db.models.Field.many_to_many" title="django.db.models.Field.many_to_many"><code class="xref py py-attr docutils literal"><span class="pre">Field.many_to_many</span></code></a>
attribute after calling <code class="docutils literal"><span class="pre">get_field()</span></code>.</p>
</div>
</dd></dl>
</div>
<div class="section" id="s-retrieving-all-field-instances-of-a-model">
<span id="retrieving-all-field-instances-of-a-model"></span><h3>Retrieving all field instances of a model<a class="headerlink" href="#retrieving-all-field-instances-of-a-model" title="Permalink to this headline">¶</a></h3>
<dl class="method">
<dt id="django.db.models.options.Options.get_fields">
<code class="descclassname">Options.</code><code class="descname">get_fields</code>(<em>include_parents=True</em>, <em>include_hidden=False</em>)<a class="reference internal" href="../../_modules/django/db/models/options.html#Options.get_fields"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.models.options.Options.get_fields" title="Permalink to this definition">¶</a></dt>
<dd><div class="versionadded">
<span class="title">New in Django 1.8.</span> </div>
<p>Returns a tuple of fields associated with a model. <code class="docutils literal"><span class="pre">get_fields()</span></code> accepts
two parameters that can be used to control which fields are returned:</p>
<dl class="docutils">
<dt><code class="docutils literal"><span class="pre">include_parents</span></code></dt>
<dd><code class="docutils literal"><span class="pre">True</span></code> by default. Recursively includes fields defined on parent
classes. If set to <code class="docutils literal"><span class="pre">False</span></code>, <code class="docutils literal"><span class="pre">get_fields()</span></code> will only search for
fields declared directly on the current model. Fields from models that
directly inherit from abstract models or proxy classes are considered
to be local, not on the parent.</dd>
<dt><code class="docutils literal"><span class="pre">include_hidden</span></code></dt>
<dd><code class="docutils literal"><span class="pre">False</span></code> by default. If set to <code class="docutils literal"><span class="pre">True</span></code>, <code class="docutils literal"><span class="pre">get_fields()</span></code> will include
fields that are used to back other field’s functionality. This will
also include any fields that have a <code class="docutils literal"><span class="pre">related_name</span></code> (such
as <a class="reference internal" href="fields.html#django.db.models.ManyToManyField" title="django.db.models.ManyToManyField"><code class="xref py py-class docutils literal"><span class="pre">ManyToManyField</span></code></a>, or
<a class="reference internal" href="fields.html#django.db.models.ForeignKey" title="django.db.models.ForeignKey"><code class="xref py py-class docutils literal"><span class="pre">ForeignKey</span></code></a>) that start with a “+”.</dd>
</dl>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">from</span> <span class="nn">django.contrib.auth.models</span> <span class="kn">import</span> <span class="n">User</span>
<span class="gp">>>> </span><span class="n">User</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_fields</span><span class="p">()</span>
<span class="go">(<ManyToOneRel: admin.logentry>,</span>
<span class="go"> <django.db.models.fields.AutoField: id>,</span>
<span class="go"> <django.db.models.fields.CharField: password>,</span>
<span class="go"> <django.db.models.fields.DateTimeField: last_login>,</span>
<span class="go"> <django.db.models.fields.BooleanField: is_superuser>,</span>
<span class="go"> <django.db.models.fields.CharField: username>,</span>
<span class="go"> <django.db.models.fields.CharField: first_name>,</span>
<span class="go"> <django.db.models.fields.CharField: last_name>,</span>
<span class="go"> <django.db.models.fields.EmailField: email>,</span>
<span class="go"> <django.db.models.fields.BooleanField: is_staff>,</span>
<span class="go"> <django.db.models.fields.BooleanField: is_active>,</span>
<span class="go"> <django.db.models.fields.DateTimeField: date_joined>,</span>
<span class="go"> <django.db.models.fields.related.ManyToManyField: groups>,</span>
<span class="go"> <django.db.models.fields.related.ManyToManyField: user_permissions>)</span>
<span class="go"># Also include hidden fields.</span>
<span class="gp">>>> </span><span class="n">User</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_fields</span><span class="p">(</span><span class="n">include_hidden</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
<span class="go">(<ManyToOneRel: auth.user_groups>,</span>
<span class="go"> <ManyToOneRel: auth.user_user_permissions>,</span>
<span class="go"> <ManyToOneRel: admin.logentry>,</span>
<span class="go"> <django.db.models.fields.AutoField: id>,</span>
<span class="go"> <django.db.models.fields.CharField: password>,</span>
<span class="go"> <django.db.models.fields.DateTimeField: last_login>,</span>
<span class="go"> <django.db.models.fields.BooleanField: is_superuser>,</span>
<span class="go"> <django.db.models.fields.CharField: username>,</span>
<span class="go"> <django.db.models.fields.CharField: first_name>,</span>
<span class="go"> <django.db.models.fields.CharField: last_name>,</span>
<span class="go"> <django.db.models.fields.EmailField: email>,</span>
<span class="go"> <django.db.models.fields.BooleanField: is_staff>,</span>
<span class="go"> <django.db.models.fields.BooleanField: is_active>,</span>
<span class="go"> <django.db.models.fields.DateTimeField: date_joined>,</span>
<span class="go"> <django.db.models.fields.related.ManyToManyField: groups>,</span>
<span class="go"> <django.db.models.fields.related.ManyToManyField: user_permissions>)</span>
</pre></div>
</div>
</dd></dl>
</div>
</div>
<div class="section" id="s-migrating-from-the-old-api">
<span id="s-migrating-old-meta-api"></span><span id="migrating-from-the-old-api"></span><span id="migrating-old-meta-api"></span><h2>Migrating from the old API<a class="headerlink" href="#migrating-from-the-old-api" title="Permalink to this headline">¶</a></h2>
<p>As part of the formalization of the <code class="docutils literal"><span class="pre">Model._meta</span></code> API (from the
<a class="reference internal" href="#django.db.models.options.Options" title="django.db.models.options.Options"><code class="xref py py-class docutils literal"><span class="pre">django.db.models.options.Options</span></code></a> class), a number of methods and
properties have been deprecated and will be removed in Django 1.10.</p>
<p>These old APIs can be replicated by either:</p>
<ul class="simple">
<li>invoking <a class="reference internal" href="#django.db.models.options.Options.get_field" title="django.db.models.options.Options.get_field"><code class="xref py py-meth docutils literal"><span class="pre">Options.get_field()</span></code></a>, or;</li>
<li>invoking <a class="reference internal" href="#django.db.models.options.Options.get_fields" title="django.db.models.options.Options.get_fields"><code class="xref py py-meth docutils literal"><span class="pre">Options.get_fields()</span></code></a> to retrieve a list of all
fields, and then filtering this list using the <a class="reference internal" href="fields.html#model-field-attributes"><span class="std std-ref">field attributes</span></a> that describe (or retrieve, in the case of
<code class="docutils literal"><span class="pre">_with_model</span></code> variants) the properties of the desired fields.</li>
</ul>
<p>Although it’s possible to make strictly equivalent replacements of the old
methods, that might not be the best approach. Taking the time to refactor any
field loops to make better use of the new API - and possibly include fields
that were previously excluded - will almost certainly result in better code.</p>
<p>Assuming you have a model named <code class="docutils literal"><span class="pre">MyModel</span></code>, the following substitutions
can be made to convert your code to the new API:</p>
<ul>
<li><p class="first"><code class="docutils literal"><span class="pre">MyModel._meta.get_field(name)</span></code>:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">f</span> <span class="o">=</span> <span class="n">MyModel</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_field</span><span class="p">(</span><span class="n">name</span><span class="p">)</span>
</pre></div>
</div>
<p>then check if:</p>
<ul class="simple">
<li><code class="docutils literal"><span class="pre">f.auto_created</span> <span class="pre">==</span> <span class="pre">False</span></code>, because the new <code class="docutils literal"><span class="pre">get_field()</span></code>
API will find “reverse” relations), and:</li>
<li><code class="docutils literal"><span class="pre">f.is_relation</span> <span class="pre">and</span> <span class="pre">f.related_model</span> <span class="pre">is</span> <span class="pre">None</span></code>, because the new
<code class="docutils literal"><span class="pre">get_field()</span></code> API will find
<a class="reference internal" href="../contrib/contenttypes.html#django.contrib.contenttypes.fields.GenericForeignKey" title="django.contrib.contenttypes.fields.GenericForeignKey"><code class="xref py py-class docutils literal"><span class="pre">GenericForeignKey</span></code></a> relations;</li>
</ul>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">MyModel._meta.get_field_by_name(name)</span></code>:</p>
<p><code class="docutils literal"><span class="pre">get_field_by_name()</span></code> returned four values:
<code class="docutils literal"><span class="pre">(field,</span> <span class="pre">model,</span> <span class="pre">direct,</span>  <span class="pre">m2m)</span></code>:</p>
<ul>
<li><p class="first"><code class="docutils literal"><span class="pre">field</span></code> can be found by <code class="docutils literal"><span class="pre">MyModel._meta.get_field(name)</span></code></p>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">model</span></code> can be found through the
<a class="reference internal" href="fields.html#django.db.models.Field.model" title="django.db.models.Field.model"><code class="xref py py-attr docutils literal"><span class="pre">model</span></code></a> attribute on the field.</p>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">direct</span></code> can be found by: <code class="docutils literal"><span class="pre">not</span> <span class="pre">field.auto_created</span> <span class="pre">or</span> <span class="pre">field.concrete</span></code></p>
<p>The <a class="reference internal" href="fields.html#django.db.models.Field.auto_created" title="django.db.models.Field.auto_created"><code class="xref py py-attr docutils literal"><span class="pre">auto_created</span></code></a> check excludes
all “forward” and “reverse” relations that are created by Django, but
this also includes <code class="docutils literal"><span class="pre">AutoField</span></code> and <code class="docutils literal"><span class="pre">OneToOneField</span></code> on proxy models.
We avoid filtering out these attributes using the
<a class="reference internal" href="fields.html#django.db.models.Field.concrete" title="django.db.models.Field.concrete"><code class="xref py py-attr docutils literal"><span class="pre">concrete</span></code></a> attribute.</p>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">m2m</span></code> can be found through the
<a class="reference internal" href="fields.html#django.db.models.Field.many_to_many" title="django.db.models.Field.many_to_many"><code class="xref py py-attr docutils literal"><span class="pre">many_to_many</span></code></a> attribute on the field.</p>
</li>
</ul>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">MyModel._meta.get_fields_with_model()</span></code>:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">[</span>
<span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="n">f</span><span class="o">.</span><span class="n">model</span> <span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">model</span> <span class="o">!=</span> <span class="n">MyModel</span> <span class="k">else</span> <span class="kc">None</span><span class="p">)</span>
<span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">MyModel</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_fields</span><span class="p">()</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">f</span><span class="o">.</span><span class="n">is_relation</span>
<span class="ow">or</span> <span class="n">f</span><span class="o">.</span><span class="n">one_to_one</span>
<span class="ow">or</span> <span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="n">many_to_one</span> <span class="ow">and</span> <span class="n">f</span><span class="o">.</span><span class="n">related_model</span><span class="p">)</span>
<span class="p">]</span>
</pre></div>
</div>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">MyModel._meta.get_concrete_fields_with_model()</span></code>:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">[</span>
<span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="n">f</span><span class="o">.</span><span class="n">model</span> <span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">model</span> <span class="o">!=</span> <span class="n">MyModel</span> <span class="k">else</span> <span class="kc">None</span><span class="p">)</span>
<span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">MyModel</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_fields</span><span class="p">()</span>
<span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">concrete</span> <span class="ow">and</span> <span class="p">(</span>
<span class="ow">not</span> <span class="n">f</span><span class="o">.</span><span class="n">is_relation</span>
<span class="ow">or</span> <span class="n">f</span><span class="o">.</span><span class="n">one_to_one</span>
<span class="ow">or</span> <span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="n">many_to_one</span> <span class="ow">and</span> <span class="n">f</span><span class="o">.</span><span class="n">related_model</span><span class="p">)</span>
<span class="p">)</span>
<span class="p">]</span>
</pre></div>
</div>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">MyModel._meta.get_m2m_with_model()</span></code>:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">[</span>
<span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="n">f</span><span class="o">.</span><span class="n">model</span> <span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">model</span> <span class="o">!=</span> <span class="n">MyModel</span> <span class="k">else</span> <span class="kc">None</span><span class="p">)</span>
<span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">MyModel</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_fields</span><span class="p">()</span>
<span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">many_to_many</span> <span class="ow">and</span> <span class="ow">not</span> <span class="n">f</span><span class="o">.</span><span class="n">auto_created</span>
<span class="p">]</span>
</pre></div>
</div>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">MyModel._meta.get_all_related_objects()</span></code>:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">[</span>
<span class="n">f</span> <span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">MyModel</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_fields</span><span class="p">()</span>
<span class="k">if</span> <span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="n">one_to_many</span> <span class="ow">or</span> <span class="n">f</span><span class="o">.</span><span class="n">one_to_one</span><span class="p">)</span>
<span class="ow">and</span> <span class="n">f</span><span class="o">.</span><span class="n">auto_created</span> <span class="ow">and</span> <span class="ow">not</span> <span class="n">f</span><span class="o">.</span><span class="n">concrete</span>
<span class="p">]</span>
</pre></div>
</div>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">MyModel._meta.get_all_related_objects_with_model()</span></code>:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">[</span>
<span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="n">f</span><span class="o">.</span><span class="n">model</span> <span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">model</span> <span class="o">!=</span> <span class="n">MyModel</span> <span class="k">else</span> <span class="kc">None</span><span class="p">)</span>
<span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">MyModel</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_fields</span><span class="p">()</span>
<span class="k">if</span> <span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="n">one_to_many</span> <span class="ow">or</span> <span class="n">f</span><span class="o">.</span><span class="n">one_to_one</span><span class="p">)</span>
<span class="ow">and</span> <span class="n">f</span><span class="o">.</span><span class="n">auto_created</span> <span class="ow">and</span> <span class="ow">not</span> <span class="n">f</span><span class="o">.</span><span class="n">concrete</span>
<span class="p">]</span>
</pre></div>
</div>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">MyModel._meta.get_all_related_many_to_many_objects()</span></code>:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">[</span>
<span class="n">f</span> <span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">MyModel</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_fields</span><span class="p">(</span><span class="n">include_hidden</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">many_to_many</span> <span class="ow">and</span> <span class="n">f</span><span class="o">.</span><span class="n">auto_created</span>
<span class="p">]</span>
</pre></div>
</div>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">MyModel._meta.get_all_related_m2m_objects_with_model()</span></code>:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">[</span>
<span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="n">f</span><span class="o">.</span><span class="n">model</span> <span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">model</span> <span class="o">!=</span> <span class="n">MyModel</span> <span class="k">else</span> <span class="kc">None</span><span class="p">)</span>
<span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">MyModel</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_fields</span><span class="p">(</span><span class="n">include_hidden</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">many_to_many</span> <span class="ow">and</span> <span class="n">f</span><span class="o">.</span><span class="n">auto_created</span>
<span class="p">]</span>
</pre></div>
</div>
</li>
<li><p class="first"><code class="docutils literal"><span class="pre">MyModel._meta.get_all_field_names()</span></code>:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">itertools</span> <span class="k">import</span> <span class="n">chain</span>
<span class="nb">list</span><span class="p">(</span><span class="nb">set</span><span class="p">(</span><span class="n">chain</span><span class="o">.</span><span class="n">from_iterable</span><span class="p">(</span>
<span class="p">(</span><span class="n">field</span><span class="o">.</span><span class="n">name</span><span class="p">,</span> <span class="n">field</span><span class="o">.</span><span class="n">attname</span><span class="p">)</span> <span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="s1">'attname'</span><span class="p">)</span> <span class="k">else</span> <span class="p">(</span><span class="n">field</span><span class="o">.</span><span class="n">name</span><span class="p">,)</span>
<span class="k">for</span> <span class="n">field</span> <span class="ow">in</span> <span class="n">MyModel</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_fields</span><span class="p">()</span>
<span class="c1"># For complete backwards compatibility, you may want to exclude</span>
<span class="c1"># GenericForeignKey from the results.</span>
<span class="k">if</span> <span class="ow">not</span> <span class="p">(</span><span class="n">field</span><span class="o">.</span><span class="n">many_to_one</span> <span class="ow">and</span> <span class="n">field</span><span class="o">.</span><span class="n">related_model</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">)</span>
<span class="p">)))</span>
</pre></div>
</div>
<p>This provides a 100% backwards compatible replacement, ensuring that both
field names and attribute names <code class="docutils literal"><span class="pre">ForeignKey</span></code>s are included, but fields
associated with <code class="docutils literal"><span class="pre">GenericForeignKey</span></code>s are not. A simpler version would be:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">[</span><span class="n">f</span><span class="o">.</span><span class="n">name</span> <span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">MyModel</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">get_fields</span><span class="p">()]</span>
</pre></div>
</div>
<p>While this isn’t 100% backwards compatible, it may be sufficient in many
situations.</p>
</li>
</ul>
</div>
</div>
</div>
</div>
</div>
<div class="yui-b" id="sidebar">
<div class="sphinxsidebar" role="navigation" aria-label="main navigation">
<div class="sphinxsidebarwrapper">
<h3><a href="../../contents.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">Model <code class="docutils literal"><span class="pre">_meta</span></code> API</a><ul>
<li><a class="reference internal" href="#field-access-api">Field access API</a><ul>
<li><a class="reference internal" href="#retrieving-a-single-field-instance-of-a-model-by-name">Retrieving a single field instance of a model by name</a></li>
<li><a class="reference internal" href="#retrieving-all-field-instances-of-a-model">Retrieving all field instances of a model</a></li>
</ul>
</li>
<li><a class="reference internal" href="#migrating-from-the-old-api">Migrating from the old API</a></li>
</ul>
</li>
</ul>
<h3>Browse</h3>
<ul>
<li>Prev: <a href="fields.html">Model field reference</a></li>
<li>Next: <a href="relations.html">Related objects reference</a></li>
</ul>
<h3>You are here:</h3>
<ul>
<li>
<a href="../../index.html">Django 1.8.19 documentation</a>
<ul><li><a href="../index.html">API Reference</a>
<ul><li><a href="index.html">Models</a>
<ul><li>Model <code class="docutils literal"><span class="pre">_meta</span></code> API</li></ul>
</li></ul></li></ul>
</li>
</ul>
<div role="note" aria-label="source link">
<h3>This Page</h3>
<ul class="this-page-menu">
<li><a href="../../_sources/ref/models/meta.txt"
rel="nofollow">Show Source</a></li>
</ul>
</div>
<div id="searchbox" style="display: none" role="search">
<h3>Quick search</h3>
<form class="search" action="../../search.html" method="get">
<div><input type="text" name="q" /></div>
<div><input type="submit" value="Go" /></div>
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
<script type="text/javascript">$('#searchbox').show(0);</script>
</div>
</div>
<h3>Last update:</h3>
<p class="topless">Mar 10, 2018</p>
</div>
</div>
<div id="ft">
<div class="nav">
« <a href="fields.html" title="Model field reference">previous</a>
|
<a href="../index.html" title="API Reference" accesskey="U">up</a>
|
<a href="relations.html" title="Related objects reference">next</a> »</div>
</div>
</div>
<div class="clearer"></div>
</div>
</body>
</html>
distrib
>
Mageia
>
6
>
armv7hl
>
media
>
core-updates
>
by-pkgid
>
65530c6176058f9b54858c3b4f6385e6
>
files
>
779
