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<div class="section" id="module-psycopg2.extras">
<span id="psycopg2-extras-miscellaneous-goodies-for-psycopg-2"></span><h1><a class="reference internal" href="#module-psycopg2.extras" title="psycopg2.extras"><tt class="xref py py-obj docutils literal"><span class="pre">psycopg2.extras</span></tt></a> – Miscellaneous goodies for Psycopg 2<a class="headerlink" href="#module-psycopg2.extras" title="Permalink to this headline">¶</a></h1>
<p>This module is a generic place used to hold little helper functions and
classes until a better place in the distribution is found.</p>
<div class="section" id="connection-and-cursor-subclasses">
<span id="cursor-subclasses"></span><h2>Connection and cursor subclasses<a class="headerlink" href="#connection-and-cursor-subclasses" title="Permalink to this headline">¶</a></h2>
<p>A few objects that change the way the results are returned by the cursor or
modify the object behavior in some other way. Typically <tt class="xref py py-obj docutils literal"><span class="pre">cursor</span></tt> subclasses
are passed as <em>cursor_factory</em> argument to <a class="reference internal" href="module.html#psycopg2.connect" title="psycopg2.connect"><tt class="xref py py-obj docutils literal"><span class="pre">connect()</span></tt></a> so that the
connection’s <a class="reference internal" href="connection.html#connection.cursor" title="connection.cursor"><tt class="xref py py-obj docutils literal"><span class="pre">cursor()</span></tt></a> method will generate objects of this
class. Alternatively a <tt class="xref py py-obj docutils literal"><span class="pre">cursor</span></tt> subclass can be used one-off by passing it
as the <em>cursor_factory</em> argument to the <tt class="xref py py-obj docutils literal"><span class="pre">cursor()</span></tt> method.</p>
<p>If you want to use a <tt class="xref py py-obj docutils literal"><span class="pre">connection</span></tt> subclass you can pass it as the
<em>connection_factory</em> argument of the <tt class="xref py py-obj docutils literal"><span class="pre">connect()</span></tt> function.</p>
<div class="section" id="dictionary-like-cursor">
<span id="dict-cursor"></span><span id="index-0"></span><h3>Dictionary-like cursor<a class="headerlink" href="#dictionary-like-cursor" title="Permalink to this headline">¶</a></h3>
<p>The dict cursors allow to access to the retrieved records using an interface
similar to the Python dictionaries instead of the tuples.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">dict_cur</span> <span class="o">=</span> <span class="n">conn</span><span class="o">.</span><span class="n">cursor</span><span class="p">(</span><span class="n">cursor_factory</span><span class="o">=</span><span class="n">psycopg2</span><span class="o">.</span><span class="n">extras</span><span class="o">.</span><span class="n">DictCursor</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">dict_cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"INSERT INTO test (num, data) VALUES(</span><span class="si">%s</span><span class="s">, </span><span class="si">%s</span><span class="s">)"</span><span class="p">,</span>
<span class="gp">... </span> <span class="p">(</span><span class="mi">100</span><span class="p">,</span> <span class="s">"abc'def"</span><span class="p">))</span>
<span class="gp">>>> </span><span class="n">dict_cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"SELECT * FROM test"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">rec</span> <span class="o">=</span> <span class="n">dict_cur</span><span class="o">.</span><span class="n">fetchone</span><span class="p">()</span>
<span class="gp">>>> </span><span class="n">rec</span><span class="p">[</span><span class="s">'id'</span><span class="p">]</span>
<span class="go">1</span>
<span class="gp">>>> </span><span class="n">rec</span><span class="p">[</span><span class="s">'num'</span><span class="p">]</span>
<span class="go">100</span>
<span class="gp">>>> </span><span class="n">rec</span><span class="p">[</span><span class="s">'data'</span><span class="p">]</span>
<span class="go">"abc'def"</span>
</pre></div>
</div>
<p>The records still support indexing as the original tuple:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">rec</span><span class="p">[</span><span class="mi">2</span><span class="p">]</span>
<span class="go">"abc'def"</span>
</pre></div>
</div>
<dl class="class">
<dt id="psycopg2.extras.DictCursor">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">DictCursor</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#psycopg2.extras.DictCursor" title="Permalink to this definition">¶</a></dt>
<dd><p>A cursor that keeps a list of column name -> index mappings.</p>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.DictConnection">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">DictConnection</tt><a class="headerlink" href="#psycopg2.extras.DictConnection" title="Permalink to this definition">¶</a></dt>
<dd><p>A connection that uses <a class="reference internal" href="#psycopg2.extras.DictCursor" title="psycopg2.extras.DictCursor"><tt class="xref py py-obj docutils literal"><span class="pre">DictCursor</span></tt></a> automatically.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">Not very useful since Psycopg 2.5: you can use <a class="reference internal" href="module.html#psycopg2.connect" title="psycopg2.connect"><tt class="xref py py-obj docutils literal"><span class="pre">psycopg2.connect</span></tt></a><tt class="docutils literal"><span class="pre">(dsn,</span> <span class="pre">cursor_factory=DictCursor)</span></tt> instead of <tt class="xref py py-obj docutils literal"><span class="pre">DictConnection</span></tt>.</p>
</div>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.DictRow">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">DictRow</tt><big>(</big><em>cursor</em><big>)</big><a class="headerlink" href="#psycopg2.extras.DictRow" title="Permalink to this definition">¶</a></dt>
<dd><p>A row object that allow by-column-name access to data.</p>
</dd></dl>
</div>
<div class="section" id="real-dictionary-cursor">
<h3>Real dictionary cursor<a class="headerlink" href="#real-dictionary-cursor" title="Permalink to this headline">¶</a></h3>
<dl class="class">
<dt id="psycopg2.extras.RealDictCursor">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">RealDictCursor</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#psycopg2.extras.RealDictCursor" title="Permalink to this definition">¶</a></dt>
<dd><p>A cursor that uses a real dict as the base type for rows.</p>
<p>Note that this cursor is extremely specialized and does not allow
the normal access (using integer indices) to fetched data. If you need
to access database rows both as a dictionary and a list, then use
the generic <a class="reference internal" href="#psycopg2.extras.DictCursor" title="psycopg2.extras.DictCursor"><tt class="xref py py-obj docutils literal"><span class="pre">DictCursor</span></tt></a> instead of <tt class="xref py py-obj docutils literal"><span class="pre">RealDictCursor</span></tt>.</p>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.RealDictConnection">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">RealDictConnection</tt><a class="headerlink" href="#psycopg2.extras.RealDictConnection" title="Permalink to this definition">¶</a></dt>
<dd><p>A connection that uses <a class="reference internal" href="#psycopg2.extras.RealDictCursor" title="psycopg2.extras.RealDictCursor"><tt class="xref py py-obj docutils literal"><span class="pre">RealDictCursor</span></tt></a> automatically.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">Not very useful since Psycopg 2.5: you can use <a class="reference internal" href="module.html#psycopg2.connect" title="psycopg2.connect"><tt class="xref py py-obj docutils literal"><span class="pre">psycopg2.connect</span></tt></a><tt class="docutils literal"><span class="pre">(dsn,</span> <span class="pre">cursor_factory=RealDictCursor)</span></tt> instead of
<tt class="xref py py-obj docutils literal"><span class="pre">RealDictConnection</span></tt>.</p>
</div>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.RealDictRow">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">RealDictRow</tt><big>(</big><em>cursor</em><big>)</big><a class="headerlink" href="#psycopg2.extras.RealDictRow" title="Permalink to this definition">¶</a></dt>
<dd><p>A <tt class="xref py py-obj docutils literal"><span class="pre">dict</span></tt> subclass representing a data record.</p>
</dd></dl>
</div>
<div class="section" id="namedtuple-cursor">
<span id="index-1"></span><h3><tt class="xref py py-obj docutils literal"><span class="pre">namedtuple</span></tt> cursor<a class="headerlink" href="#namedtuple-cursor" title="Permalink to this headline">¶</a></h3>
<div class="versionadded">
<p><span>New in version 2.3.</span></p>
</div>
<p>These objects require <a class="reference external" href="http://docs.python.org/3.2/library/collections.html#collections.namedtuple" title="(in Python v3.2)"><tt class="xref py py-func docutils literal"><span class="pre">collections.namedtuple()</span></tt></a> to be found, so it is
available out-of-the-box only from Python 2.6. Anyway, the namedtuple
implementation is compatible with previous Python versions, so all you
have to do is to <a class="reference external" href="http://code.activestate.com/recipes/500261-named-tuples/">download it</a> and make it available where we
expect it to be...</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">somewhere</span> <span class="kn">import</span> <span class="n">namedtuple</span>
<span class="kn">import</span> <span class="nn">collections</span>
<span class="n">collections</span><span class="o">.</span><span class="n">namedtuple</span> <span class="o">=</span> <span class="n">namedtuple</span>
<span class="kn">from</span> <span class="nn">psycopg.extras</span> <span class="kn">import</span> <span class="n">NamedTupleConnection</span>
<span class="c"># ...</span>
</pre></div>
</div>
<dl class="class">
<dt id="psycopg2.extras.NamedTupleCursor">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">NamedTupleCursor</tt><a class="headerlink" href="#psycopg2.extras.NamedTupleCursor" title="Permalink to this definition">¶</a></dt>
<dd><p>A cursor that generates results as <a class="reference external" href="http://docs.python.org/3.2/library/collections.html#collections.namedtuple" title="(in Python v3.2)"><tt class="xref py py-obj docutils literal"><span class="pre">namedtuple</span></tt></a>.</p>
<p><tt class="xref py py-obj docutils literal"><span class="pre">fetch*()</span></tt> methods will return named tuples instead of regular tuples, so
their elements can be accessed both as regular numeric items as well as
attributes.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">nt_cur</span> <span class="o">=</span> <span class="n">conn</span><span class="o">.</span><span class="n">cursor</span><span class="p">(</span><span class="n">cursor_factory</span><span class="o">=</span><span class="n">psycopg2</span><span class="o">.</span><span class="n">extras</span><span class="o">.</span><span class="n">NamedTupleCursor</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">rec</span> <span class="o">=</span> <span class="n">nt_cur</span><span class="o">.</span><span class="n">fetchone</span><span class="p">()</span>
<span class="gp">>>> </span><span class="n">rec</span>
<span class="go">Record(id=1, num=100, data="abc'def")</span>
<span class="gp">>>> </span><span class="n">rec</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span>
<span class="go">100</span>
<span class="gp">>>> </span><span class="n">rec</span><span class="o">.</span><span class="n">data</span>
<span class="go">"abc'def"</span>
</pre></div>
</div>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.NamedTupleConnection">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">NamedTupleConnection</tt><a class="headerlink" href="#psycopg2.extras.NamedTupleConnection" title="Permalink to this definition">¶</a></dt>
<dd><p>A connection that uses <a class="reference internal" href="#psycopg2.extras.NamedTupleCursor" title="psycopg2.extras.NamedTupleCursor"><tt class="xref py py-obj docutils literal"><span class="pre">NamedTupleCursor</span></tt></a> automatically.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">Not very useful since Psycopg 2.5: you can use <a class="reference internal" href="module.html#psycopg2.connect" title="psycopg2.connect"><tt class="xref py py-obj docutils literal"><span class="pre">psycopg2.connect</span></tt></a><tt class="docutils literal"><span class="pre">(dsn,</span> <span class="pre">cursor_factory=NamedTupleCursor)</span></tt> instead of
<tt class="xref py py-obj docutils literal"><span class="pre">NamedTupleConnection</span></tt>.</p>
</div>
</dd></dl>
</div>
<div class="section" id="logging-cursor">
<span id="index-2"></span><h3>Logging cursor<a class="headerlink" href="#logging-cursor" title="Permalink to this headline">¶</a></h3>
<dl class="class">
<dt id="psycopg2.extras.LoggingConnection">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">LoggingConnection</tt><a class="headerlink" href="#psycopg2.extras.LoggingConnection" title="Permalink to this definition">¶</a></dt>
<dd><p>A connection that logs all queries to a file or <a class="reference external" href="http://docs.python.org/library/logging.html">logger</a> object.</p>
<dl class="method">
<dt id="psycopg2.extras.LoggingConnection.filter">
<tt class="descname">filter</tt><big>(</big><em>msg</em>, <em>curs</em><big>)</big><a class="headerlink" href="#psycopg2.extras.LoggingConnection.filter" title="Permalink to this definition">¶</a></dt>
<dd><p>Filter the query before logging it.</p>
<p>This is the method to overwrite to filter unwanted queries out of the
log or to add some extra data to the output. The default implementation
just does nothing.</p>
</dd></dl>
<dl class="method">
<dt id="psycopg2.extras.LoggingConnection.initialize">
<tt class="descname">initialize</tt><big>(</big><em>logobj</em><big>)</big><a class="headerlink" href="#psycopg2.extras.LoggingConnection.initialize" title="Permalink to this definition">¶</a></dt>
<dd><p>Initialize the connection to log to <tt class="xref py py-obj docutils literal"><span class="pre">logobj</span></tt>.</p>
<p>The <tt class="xref py py-obj docutils literal"><span class="pre">logobj</span></tt> parameter can be an open file object or a Logger
instance from the standard logging module.</p>
</dd></dl>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.LoggingCursor">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">LoggingCursor</tt><a class="headerlink" href="#psycopg2.extras.LoggingCursor" title="Permalink to this definition">¶</a></dt>
<dd><p>A cursor that logs queries using its connection logging facilities.</p>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.MinTimeLoggingConnection">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">MinTimeLoggingConnection</tt><a class="headerlink" href="#psycopg2.extras.MinTimeLoggingConnection" title="Permalink to this definition">¶</a></dt>
<dd><p>A connection that logs queries based on execution time.</p>
<p>This is just an example of how to sub-class <a class="reference internal" href="#psycopg2.extras.LoggingConnection" title="psycopg2.extras.LoggingConnection"><tt class="xref py py-obj docutils literal"><span class="pre">LoggingConnection</span></tt></a> to
provide some extra filtering for the logged queries. Both the
<tt class="xref py py-obj docutils literal"><span class="pre">initialize()</span></tt> and <tt class="xref py py-obj docutils literal"><span class="pre">filter()</span></tt> methods are overwritten to make sure
that only queries executing for more than <tt class="docutils literal"><span class="pre">mintime</span></tt> ms are logged.</p>
<p>Note that this connection uses the specialized cursor
<a class="reference internal" href="#psycopg2.extras.MinTimeLoggingCursor" title="psycopg2.extras.MinTimeLoggingCursor"><tt class="xref py py-obj docutils literal"><span class="pre">MinTimeLoggingCursor</span></tt></a>.</p>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.MinTimeLoggingCursor">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">MinTimeLoggingCursor</tt><a class="headerlink" href="#psycopg2.extras.MinTimeLoggingCursor" title="Permalink to this definition">¶</a></dt>
<dd><p>The cursor sub-class companion to <a class="reference internal" href="#psycopg2.extras.MinTimeLoggingConnection" title="psycopg2.extras.MinTimeLoggingConnection"><tt class="xref py py-obj docutils literal"><span class="pre">MinTimeLoggingConnection</span></tt></a>.</p>
</dd></dl>
</div>
</div>
<div class="section" id="additional-data-types">
<span id="index-3"></span><h2>Additional data types<a class="headerlink" href="#additional-data-types" title="Permalink to this headline">¶</a></h2>
<div class="section" id="json-adaptation">
<span id="adapt-json"></span><span id="index-4"></span><h3><a class="reference external" href="http://www.json.org/">JSON</a> adaptation<a class="headerlink" href="#json-adaptation" title="Permalink to this headline">¶</a></h3>
<div class="versionadded">
<p><span>New in version 2.5.</span></p>
</div>
<p>Psycopg can adapt Python objects to and from the PostgreSQL <a class="reference external" href="http://www.postgresql.org/docs/current/static/datatype-json.html"><tt class="sql docutils literal"><span class="pre">json</span></tt></a> type.
With PostgreSQL 9.2 adaptation is available out-of-the-box. To use JSON data
with previous database versions (either with the <a class="reference external" href="http://people.planetpostgresql.org/andrew/index.php?/archives/255-JSON-for-PG-9.2-...-and-now-for-9.1!.html">9.1 json extension</a>, but
even if you want to convert text fields to JSON) you can use
<a class="reference internal" href="#psycopg2.extras.register_json" title="psycopg2.extras.register_json"><tt class="xref py py-obj docutils literal"><span class="pre">register_json()</span></tt></a>.</p>
<p>The Python library used to convert Python objects to JSON depends on the
language version: with Python 2.6 and following the <a class="reference external" href="http://docs.python.org/3.2/library/json.html#json" title="(in Python v3.2)"><tt class="xref py py-mod docutils literal"><span class="pre">json</span></tt></a> module from
the standard library is used; with previous versions the <a class="reference external" href="http://pypi.python.org/pypi/simplejson/">simplejson</a> module
is used if available. Note that the last <tt class="xref py py-obj docutils literal"><span class="pre">simplejson</span></tt> version supporting
Python 2.4 is the 2.0.9.</p>
<p>In order to pass a Python object to the database as query argument you can use
the <a class="reference internal" href="#psycopg2.extras.Json" title="psycopg2.extras.Json"><tt class="xref py py-obj docutils literal"><span class="pre">Json</span></tt></a> adapter:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">curs</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"insert into mytable (jsondata) values (</span><span class="si">%s</span><span class="s">)"</span><span class="p">,</span>
<span class="p">[</span><span class="n">Json</span><span class="p">({</span><span class="s">'a'</span><span class="p">:</span> <span class="mi">100</span><span class="p">})])</span>
</pre></div>
</div>
<p>Reading from the database, <tt class="sql docutils literal"><span class="pre">json</span></tt> values will be automatically converted to
Python objects.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p>You can use <a class="reference internal" href="extensions.html#psycopg2.extensions.register_adapter" title="psycopg2.extensions.register_adapter"><tt class="xref py py-obj docutils literal"><span class="pre">register_adapter()</span></tt></a> to adapt any Python
dictionary to JSON, either registering <a class="reference internal" href="#psycopg2.extras.Json" title="psycopg2.extras.Json"><tt class="xref py py-obj docutils literal"><span class="pre">Json</span></tt></a> or any subclass or factory
creating a compatible adapter:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">psycopg2</span><span class="o">.</span><span class="n">extensions</span><span class="o">.</span><span class="n">register_adapter</span><span class="p">(</span><span class="nb">dict</span><span class="p">,</span> <span class="n">psycopg2</span><span class="o">.</span><span class="n">extras</span><span class="o">.</span><span class="n">Json</span><span class="p">)</span>
</pre></div>
</div>
<p class="last">This setting is global though, so it is not compatible with similar
adapters such as the one registered by <a class="reference internal" href="#psycopg2.extras.register_hstore" title="psycopg2.extras.register_hstore"><tt class="xref py py-obj docutils literal"><span class="pre">register_hstore()</span></tt></a>. Any other
object supported by JSON can be registered the same way, but this will
clobber the default adaptation rule, so be careful to unwanted side
effects.</p>
</div>
<p>If you want to customize the adaptation from Python to PostgreSQL you can
either provide a custom <tt class="xref py py-obj docutils literal"><span class="pre">dumps()</span></tt> function to <tt class="xref py py-obj docutils literal"><span class="pre">Json</span></tt>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">curs</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"insert into mytable (jsondata) values (</span><span class="si">%s</span><span class="s">)"</span><span class="p">,</span>
<span class="p">[</span><span class="n">Json</span><span class="p">({</span><span class="s">'a'</span><span class="p">:</span> <span class="mi">100</span><span class="p">},</span> <span class="n">dumps</span><span class="o">=</span><span class="n">simplejson</span><span class="o">.</span><span class="n">dumps</span><span class="p">)])</span>
</pre></div>
</div>
<p>or you can subclass it overriding the <a class="reference internal" href="#psycopg2.extras.Json.dumps" title="psycopg2.extras.Json.dumps"><tt class="xref py py-obj docutils literal"><span class="pre">dumps()</span></tt></a> method:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">class</span> <span class="nc">MyJson</span><span class="p">(</span><span class="n">Json</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">dumps</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">obj</span><span class="p">):</span>
<span class="k">return</span> <span class="n">simplejson</span><span class="o">.</span><span class="n">dumps</span><span class="p">(</span><span class="n">obj</span><span class="p">)</span>
<span class="n">curs</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"insert into mytable (jsondata) values (</span><span class="si">%s</span><span class="s">)"</span><span class="p">,</span>
<span class="p">[</span><span class="n">MyJson</span><span class="p">({</span><span class="s">'a'</span><span class="p">:</span> <span class="mi">100</span><span class="p">})])</span>
</pre></div>
</div>
<p>Customizing the conversion from PostgreSQL to Python can be done passing a
custom <tt class="xref py py-obj docutils literal"><span class="pre">loads()</span></tt> function to <a class="reference internal" href="#psycopg2.extras.register_json" title="psycopg2.extras.register_json"><tt class="xref py py-obj docutils literal"><span class="pre">register_json()</span></tt></a> (or <a class="reference internal" href="#psycopg2.extras.register_default_json" title="psycopg2.extras.register_default_json"><tt class="xref py py-obj docutils literal"><span class="pre">register_default_json()</span></tt></a>
for PostgreSQL 9.2). For example, if you want to convert the float values
from <tt class="sql docutils literal"><span class="pre">json</span></tt> into <a class="reference external" href="http://docs.python.org/3.2/library/decimal.html#decimal.Decimal" title="(in Python v3.2)"><tt class="xref py py-class docutils literal"><span class="pre">Decimal</span></tt></a> you can use:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">loads</span> <span class="o">=</span> <span class="k">lambda</span> <span class="n">x</span><span class="p">:</span> <span class="n">json</span><span class="o">.</span><span class="n">loads</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">parse_float</span><span class="o">=</span><span class="n">Decimal</span><span class="p">)</span>
<span class="n">psycopg2</span><span class="o">.</span><span class="n">extras</span><span class="o">.</span><span class="n">register_json</span><span class="p">(</span><span class="n">conn</span><span class="p">,</span> <span class="n">loads</span><span class="o">=</span><span class="n">loads</span><span class="p">)</span>
</pre></div>
</div>
<dl class="class">
<dt id="psycopg2.extras.Json">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">Json</tt><big>(</big><em>adapted</em>, <em>dumps=None</em><big>)</big><a class="headerlink" href="#psycopg2.extras.Json" title="Permalink to this definition">¶</a></dt>
<dd><p>An <a class="reference internal" href="extensions.html#psycopg2.extensions.ISQLQuote" title="psycopg2.extensions.ISQLQuote"><tt class="xref py py-obj docutils literal"><span class="pre">ISQLQuote</span></tt></a> wrapper to adapt a Python object to
<tt class="sql docutils literal"><span class="pre">json</span></tt> data type.</p>
<p><tt class="xref py py-obj docutils literal"><span class="pre">Json</span></tt> can be used to wrap any object supported by the provided <em>dumps</em>
function. If none is provided, the standard <a class="reference external" href="http://docs.python.org/3.2/library/json.html#json.dumps" title="(in Python v3.2)"><tt class="xref py py-func docutils literal"><span class="pre">json.dumps()</span></tt></a> is
used (<tt class="xref py py-obj docutils literal"><span class="pre">simplejson</span></tt> for Python < 2.6;
<a class="reference internal" href="extensions.html#psycopg2.extensions.ISQLQuote.getquoted" title="psycopg2.extensions.ISQLQuote.getquoted"><tt class="xref py py-obj docutils literal"><span class="pre">getquoted()</span></tt></a> will raise <tt class="xref py py-obj docutils literal"><span class="pre">ImportError</span></tt> if
the module is not available).</p>
<dl class="method">
<dt id="psycopg2.extras.Json.dumps">
<tt class="descname">dumps</tt><big>(</big><em>obj</em><big>)</big><a class="headerlink" href="#psycopg2.extras.Json.dumps" title="Permalink to this definition">¶</a></dt>
<dd><p>Serialize <em>obj</em> in JSON format.</p>
<p>The default is to call <tt class="xref py py-obj docutils literal"><span class="pre">json.dumps()</span></tt> or the <em>dumps</em> function
provided in the constructor. You can override this method to create a
customized JSON wrapper.</p>
</dd></dl>
</dd></dl>
<dl class="function">
<dt id="psycopg2.extras.register_json">
<tt class="descclassname">psycopg2.extras.</tt><tt class="descname">register_json</tt><big>(</big><em>conn_or_curs=None</em>, <em>globally=False</em>, <em>loads=None</em>, <em>oid=None</em>, <em>array_oid=None</em><big>)</big><a class="headerlink" href="#psycopg2.extras.register_json" title="Permalink to this definition">¶</a></dt>
<dd><p>Create and register typecasters converting <tt class="sql docutils literal"><span class="pre">json</span></tt> type to Python objects.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>conn_or_curs</strong> – a connection or cursor used to find the <tt class="sql docutils literal"><span class="pre">json</span></tt>
and <tt class="sql docutils literal"><span class="pre">json[]</span></tt> oids; the typecasters are registered in a scope
limited to this object, unless <em>globally</em> is set to <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt>. It can be
<tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt> if the oids are provided</li>
<li><strong>globally</strong> – if <tt class="xref py py-obj docutils literal"><span class="pre">False</span></tt> register the typecasters only on
<em>conn_or_curs</em>, otherwise register them globally</li>
<li><strong>loads</strong> – the function used to parse the data into a Python object. If
<tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt> use <tt class="xref py py-obj docutils literal"><span class="pre">json.loads()</span></tt>, where <tt class="xref py py-obj docutils literal"><span class="pre">json</span></tt> is the module chosen
according to the Python version (see above)</li>
<li><strong>oid</strong> – the OID of the <tt class="sql docutils literal"><span class="pre">json</span></tt> type if known; If not, it will be
queried on <em>conn_or_curs</em></li>
<li><strong>array_oid</strong> – the OID of the <tt class="sql docutils literal"><span class="pre">json[]</span></tt> array type if known;
if not, it will be queried on <em>conn_or_curs</em></li>
</ul>
</td>
</tr>
</tbody>
</table>
<p>The connection or cursor passed to the function will be used to query the
database and look for the OID of the <tt class="sql docutils literal"><span class="pre">json</span></tt> type. No query is
performed if <em>oid</em> and <em>array_oid</em> are provided. Raise
<a class="reference internal" href="module.html#psycopg2.ProgrammingError" title="psycopg2.ProgrammingError"><tt class="xref py py-obj docutils literal"><span class="pre">ProgrammingError</span></tt></a> if the type is not found.</p>
</dd></dl>
<dl class="function">
<dt id="psycopg2.extras.register_default_json">
<tt class="descclassname">psycopg2.extras.</tt><tt class="descname">register_default_json</tt><big>(</big><em>conn_or_curs=None</em>, <em>globally=False</em>, <em>loads=None</em><big>)</big><a class="headerlink" href="#psycopg2.extras.register_default_json" title="Permalink to this definition">¶</a></dt>
<dd><p>Create and register <tt class="sql docutils literal"><span class="pre">json</span></tt> typecasters for PostgreSQL 9.2 and following.</p>
<p>Since PostgreSQL 9.2 <tt class="sql docutils literal"><span class="pre">json</span></tt> is a builtin type, hence its oid is known
and fixed. This function allows specifying a customized <em>loads</em> function
for the default <tt class="sql docutils literal"><span class="pre">json</span></tt> type without querying the database.
All the parameters have the same meaning of <a class="reference internal" href="#psycopg2.extras.register_json" title="psycopg2.extras.register_json"><tt class="xref py py-obj docutils literal"><span class="pre">register_json()</span></tt></a>.</p>
</dd></dl>
</div>
<div class="section" id="hstore-data-type">
<span id="adapt-hstore"></span><span id="index-5"></span><h3>Hstore data type<a class="headerlink" href="#hstore-data-type" title="Permalink to this headline">¶</a></h3>
<div class="versionadded">
<p><span>New in version 2.3.</span></p>
</div>
<p>The <a class="reference external" href="http://www.postgresql.org/docs/current/static/hstore.html"><tt class="sql docutils literal"><span class="pre">hstore</span></tt></a> data type is a key-value store embedded in PostgreSQL. It has
been available for several server versions but with the release 9.0 it has
been greatly improved in capacity and usefulness with the addition of many
functions. It supports GiST or GIN indexes allowing search by keys or
key/value pairs as well as regular BTree indexes for equality, uniqueness etc.</p>
<p>Psycopg can convert Python <tt class="xref py py-obj docutils literal"><span class="pre">dict</span></tt> objects to and from <tt class="sql docutils literal"><span class="pre">hstore</span></tt> structures.
Only dictionaries with string/unicode keys and values are supported. <tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt>
is also allowed as value but not as a key. Psycopg uses a more efficient <tt class="sql docutils literal"><span class="pre">hstore</span></tt>
representation when dealing with PostgreSQL 9.0 but previous server versions
are supported as well. By default the adapter/typecaster are disabled: they
can be enabled using the <a class="reference internal" href="#psycopg2.extras.register_hstore" title="psycopg2.extras.register_hstore"><tt class="xref py py-obj docutils literal"><span class="pre">register_hstore()</span></tt></a> function.</p>
<dl class="function">
<dt id="psycopg2.extras.register_hstore">
<tt class="descclassname">psycopg2.extras.</tt><tt class="descname">register_hstore</tt><big>(</big><em>conn_or_curs</em>, <em>globally=False</em>, <em>unicode=False</em>, <em>oid=None</em>, <em>array_oid=None</em><big>)</big><a class="headerlink" href="#psycopg2.extras.register_hstore" title="Permalink to this definition">¶</a></dt>
<dd><p>Register adapter and typecaster for <tt class="xref py py-obj docutils literal"><span class="pre">dict</span></tt>-<tt class="sql docutils literal"><span class="pre">hstore</span></tt> conversions.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>conn_or_curs</strong> – a connection or cursor: the typecaster will be
registered only on this object unless <em>globally</em> is set to <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt></li>
<li><strong>globally</strong> – register the adapter globally, not only on <em>conn_or_curs</em></li>
<li><strong>unicode</strong> – if <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt>, keys and values returned from the database
will be <tt class="xref py py-obj docutils literal"><span class="pre">unicode</span></tt> instead of <tt class="xref py py-obj docutils literal"><span class="pre">str</span></tt>. The option is not available on
Python 3</li>
<li><strong>oid</strong> – the OID of the <tt class="sql docutils literal"><span class="pre">hstore</span></tt> type if known. If not, it will be
queried on <em>conn_or_curs</em>.</li>
<li><strong>array_oid</strong> – the OID of the <tt class="sql docutils literal"><span class="pre">hstore</span></tt> array type if known. If not, it
will be queried on <em>conn_or_curs</em>.</li>
</ul>
</td>
</tr>
</tbody>
</table>
<p>The connection or cursor passed to the function will be used to query the
database and look for the OID of the <tt class="sql docutils literal"><span class="pre">hstore</span></tt> type (which may be different
across databases). If querying is not desirable (e.g. with
<a class="reference internal" href="advanced.html#async-support"><em>asynchronous connections</em></a>) you may specify it in the
<em>oid</em> parameter, which can be found using a query such as <tt class="sql docutils literal"><span class="pre">SELECT</span>
<span class="pre">'hstore'::regtype::oid</span></tt>. Analogously you can obtain a value for <em>array_oid</em>
using a query such as <tt class="sql docutils literal"><span class="pre">SELECT</span> <span class="pre">'hstore[]'::regtype::oid</span></tt>.</p>
<p>Note that, when passing a dictionary from Python to the database, both
strings and unicode keys and values are supported. Dictionaries returned
from the database have keys/values according to the <em>unicode</em> parameter.</p>
<p>The <tt class="sql docutils literal"><span class="pre">hstore</span></tt> contrib module must be already installed in the database
(executing the <tt class="docutils literal"><span class="pre">hstore.sql</span></tt> script in your <tt class="docutils literal"><span class="pre">contrib</span></tt> directory).
Raise <a class="reference internal" href="module.html#psycopg2.ProgrammingError" title="psycopg2.ProgrammingError"><tt class="xref py py-obj docutils literal"><span class="pre">ProgrammingError</span></tt></a> if the type is not found.</p>
<div class="versionchanged">
<p><span>Changed in version 2.4: </span>added the <em>oid</em> parameter. If not specified, the typecaster is
installed also if <tt class="sql docutils literal"><span class="pre">hstore</span></tt> is not installed in the <tt class="sql docutils literal"><span class="pre">public</span></tt>
schema.</p>
</div>
<div class="versionchanged">
<p><span>Changed in version 2.4.3: </span>added support for <tt class="sql docutils literal"><span class="pre">hstore</span></tt> array.</p>
</div>
</dd></dl>
</div>
<div class="section" id="composite-types-casting">
<span id="adapt-composite"></span><span id="index-6"></span><h3>Composite types casting<a class="headerlink" href="#composite-types-casting" title="Permalink to this headline">¶</a></h3>
<div class="versionadded">
<p><span>New in version 2.4.</span></p>
</div>
<p>Using <a class="reference internal" href="#psycopg2.extras.register_composite" title="psycopg2.extras.register_composite"><tt class="xref py py-obj docutils literal"><span class="pre">register_composite()</span></tt></a> it is possible to cast a PostgreSQL composite
type (either created with the <a class="reference external" href="http://www.postgresql.org/docs/current/static/sql-createtype.html"><tt class="sql docutils literal"><span class="pre">CREATE</span> <span class="pre">TYPE</span></tt></a> command or implicitly defined
after a table row type) into a Python named tuple, or into a regular tuple if
<a class="reference external" href="http://docs.python.org/3.2/library/collections.html#collections.namedtuple" title="(in Python v3.2)"><tt class="xref py py-func docutils literal"><span class="pre">collections.namedtuple()</span></tt></a> is not found.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"CREATE TYPE card AS (value int, suit text);"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">psycopg2</span><span class="o">.</span><span class="n">extras</span><span class="o">.</span><span class="n">register_composite</span><span class="p">(</span><span class="s">'card'</span><span class="p">,</span> <span class="n">cur</span><span class="p">)</span>
<span class="go"><psycopg2.extras.CompositeCaster object at 0x...></span>
<span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"select (8, 'hearts')::card"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">fetchone</span><span class="p">()[</span><span class="mi">0</span><span class="p">]</span>
<span class="go">card(value=8, suit='hearts')</span>
</pre></div>
</div>
<p>Nested composite types are handled as expected, provided that the type of the
composite components are registered as well.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"CREATE TYPE card_back AS (face card, back text);"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">psycopg2</span><span class="o">.</span><span class="n">extras</span><span class="o">.</span><span class="n">register_composite</span><span class="p">(</span><span class="s">'card_back'</span><span class="p">,</span> <span class="n">cur</span><span class="p">)</span>
<span class="go"><psycopg2.extras.CompositeCaster object at 0x...></span>
<span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"select ((8, 'hearts'), 'blue')::card_back"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">fetchone</span><span class="p">()[</span><span class="mi">0</span><span class="p">]</span>
<span class="go">card_back(face=card(value=8, suit='hearts'), back='blue')</span>
</pre></div>
</div>
<p>Adaptation from Python tuples to composite types is automatic instead and
requires no adapter registration.</p>
<div class="admonition note" id="custom-composite">
<p class="first admonition-title">Note</p>
<p>If you want to convert PostgreSQL composite types into something different
than a <tt class="xref py py-obj docutils literal"><span class="pre">namedtuple</span></tt> you can subclass the <a class="reference internal" href="#psycopg2.extras.CompositeCaster" title="psycopg2.extras.CompositeCaster"><tt class="xref py py-obj docutils literal"><span class="pre">CompositeCaster</span></tt></a> overriding
<a class="reference internal" href="#psycopg2.extras.CompositeCaster.make" title="psycopg2.extras.CompositeCaster.make"><tt class="xref py py-obj docutils literal"><span class="pre">make()</span></tt></a>. For example, if you want to convert your type
into a Python dictionary you can use:</p>
<div class="last highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="k">class</span> <span class="nc">DictComposite</span><span class="p">(</span><span class="n">psycopg2</span><span class="o">.</span><span class="n">extras</span><span class="o">.</span><span class="n">CompositeCaster</span><span class="p">):</span>
<span class="gp">... </span> <span class="k">def</span> <span class="nf">make</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">values</span><span class="p">):</span>
<span class="gp">... </span> <span class="k">return</span> <span class="nb">dict</span><span class="p">(</span><span class="nb">zip</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">attnames</span><span class="p">,</span> <span class="n">values</span><span class="p">))</span>
<span class="gp">>>> </span><span class="n">psycopg2</span><span class="o">.</span><span class="n">extras</span><span class="o">.</span><span class="n">register_composite</span><span class="p">(</span><span class="s">'card'</span><span class="p">,</span> <span class="n">cur</span><span class="p">,</span>
<span class="gp">... </span> <span class="n">factory</span><span class="o">=</span><span class="n">DictComposite</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"select (8, 'hearts')::card"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">fetchone</span><span class="p">()[</span><span class="mi">0</span><span class="p">]</span>
<span class="go">{'suit': 'hearts', 'value': 8}</span>
</pre></div>
</div>
</div>
<dl class="function">
<dt id="psycopg2.extras.register_composite">
<tt class="descclassname">psycopg2.extras.</tt><tt class="descname">register_composite</tt><big>(</big><em>name</em>, <em>conn_or_curs</em>, <em>globally=False</em>, <em>factory=None</em><big>)</big><a class="headerlink" href="#psycopg2.extras.register_composite" title="Permalink to this definition">¶</a></dt>
<dd><p>Register a typecaster to convert a composite type into a tuple.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>name</strong> – the name of a PostgreSQL composite type, e.g. created using
the <a class="reference external" href="http://www.postgresql.org/docs/current/static/sql-createtype.html"><tt class="sql docutils literal"><span class="pre">CREATE</span> <span class="pre">TYPE</span></tt></a> command</li>
<li><strong>conn_or_curs</strong> – a connection or cursor used to find the type oid and
components; the typecaster is registered in a scope limited to this
object, unless <em>globally</em> is set to <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt></li>
<li><strong>globally</strong> – if <tt class="xref py py-obj docutils literal"><span class="pre">False</span></tt> (default) register the typecaster only on
<em>conn_or_curs</em>, otherwise register it globally</li>
<li><strong>factory</strong> – if specified it should be a <a class="reference internal" href="#psycopg2.extras.CompositeCaster" title="psycopg2.extras.CompositeCaster"><tt class="xref py py-obj docutils literal"><span class="pre">CompositeCaster</span></tt></a> subclass: use
it to <a class="reference internal" href="#custom-composite"><em>customize how to cast composite types</em></a></li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first last">the registered <a class="reference internal" href="#psycopg2.extras.CompositeCaster" title="psycopg2.extras.CompositeCaster"><tt class="xref py py-obj docutils literal"><span class="pre">CompositeCaster</span></tt></a> or <em>factory</em> instance
responsible for the conversion</p>
</td>
</tr>
</tbody>
</table>
<div class="versionchanged">
<p><span>Changed in version 2.4.3: </span>added support for array of composite types</p>
</div>
<div class="versionchanged">
<p><span>Changed in version 2.5: </span>added the <em>factory</em> parameter</p>
</div>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.CompositeCaster">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">CompositeCaster</tt><big>(</big><em>name</em>, <em>oid</em>, <em>attrs</em>, <em>array_oid=None</em>, <em>schema=None</em><big>)</big><a class="headerlink" href="#psycopg2.extras.CompositeCaster" title="Permalink to this definition">¶</a></dt>
<dd><p>Helps conversion of a PostgreSQL composite type into a Python object.</p>
<p>The class is usually created by the <a class="reference internal" href="#psycopg2.extras.register_composite" title="psycopg2.extras.register_composite"><tt class="xref py py-obj docutils literal"><span class="pre">register_composite()</span></tt></a> function.
You may want to create and register manually instances of the class if
querying the database at registration time is not desirable (such as when
using an <a class="reference internal" href="advanced.html#async-support"><em>asynchronous connections</em></a>).</p>
<dl class="method">
<dt id="psycopg2.extras.CompositeCaster.make">
<tt class="descname">make</tt><big>(</big><em>values</em><big>)</big><a class="headerlink" href="#psycopg2.extras.CompositeCaster.make" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a new Python object representing the data being casted.</p>
<p><em>values</em> is the list of attributes, already casted into their Python
representation.</p>
<p>You can subclass this method to <a class="reference internal" href="#custom-composite"><em>customize the composite cast</em></a>.</p>
<div class="versionadded">
<p><span>New in version 2.5.</span></p>
</div>
</dd></dl>
<p>Object attributes:</p>
<dl class="attribute">
<dt id="psycopg2.extras.CompositeCaster.name">
<tt class="descname">name</tt><a class="headerlink" href="#psycopg2.extras.CompositeCaster.name" title="Permalink to this definition">¶</a></dt>
<dd><p>The name of the PostgreSQL type.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.CompositeCaster.schema">
<tt class="descname">schema</tt><a class="headerlink" href="#psycopg2.extras.CompositeCaster.schema" title="Permalink to this definition">¶</a></dt>
<dd><p>The schema where the type is defined.</p>
<div class="versionadded">
<p><span>New in version 2.5.</span></p>
</div>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.CompositeCaster.oid">
<tt class="descname">oid</tt><a class="headerlink" href="#psycopg2.extras.CompositeCaster.oid" title="Permalink to this definition">¶</a></dt>
<dd><p>The oid of the PostgreSQL type.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.CompositeCaster.array_oid">
<tt class="descname">array_oid</tt><a class="headerlink" href="#psycopg2.extras.CompositeCaster.array_oid" title="Permalink to this definition">¶</a></dt>
<dd><p>The oid of the PostgreSQL array type, if available.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.CompositeCaster.type">
<tt class="descname">type</tt><a class="headerlink" href="#psycopg2.extras.CompositeCaster.type" title="Permalink to this definition">¶</a></dt>
<dd><p>The type of the Python objects returned. If <a class="reference external" href="http://docs.python.org/3.2/library/collections.html#collections.namedtuple" title="(in Python v3.2)"><tt class="xref py py-func docutils literal"><span class="pre">collections.namedtuple()</span></tt></a>
is available, it is a named tuple with attributes equal to the type
components. Otherwise it is just the <tt class="xref py py-obj docutils literal"><span class="pre">tuple</span></tt> object.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.CompositeCaster.attnames">
<tt class="descname">attnames</tt><a class="headerlink" href="#psycopg2.extras.CompositeCaster.attnames" title="Permalink to this definition">¶</a></dt>
<dd><p>List of component names of the type to be casted.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.CompositeCaster.atttypes">
<tt class="descname">atttypes</tt><a class="headerlink" href="#psycopg2.extras.CompositeCaster.atttypes" title="Permalink to this definition">¶</a></dt>
<dd><p>List of component type oids of the type to be casted.</p>
</dd></dl>
</dd></dl>
</div>
<div class="section" id="range-data-types">
<span id="adapt-range"></span><span id="index-7"></span><h3>Range data types<a class="headerlink" href="#range-data-types" title="Permalink to this headline">¶</a></h3>
<div class="versionadded">
<p><span>New in version 2.5.</span></p>
</div>
<p>Psycopg offers a <a class="reference internal" href="#psycopg2.extras.Range" title="psycopg2.extras.Range"><tt class="xref py py-obj docutils literal"><span class="pre">Range</span></tt></a> Python type and supports adaptation between them and
PostgreSQL <a class="reference external" href="http://www.postgresql.org/docs/current/static/rangetypes.html"><tt class="sql docutils literal"><span class="pre">range</span></tt></a> types. Builtin <tt class="sql docutils literal"><span class="pre">range</span></tt> types are supported out-of-the-box;
user-defined <tt class="sql docutils literal"><span class="pre">range</span></tt> types can be adapted using <a class="reference internal" href="#psycopg2.extras.register_range" title="psycopg2.extras.register_range"><tt class="xref py py-obj docutils literal"><span class="pre">register_range()</span></tt></a>.</p>
<dl class="class">
<dt id="psycopg2.extras.Range">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">Range</tt><big>(</big><em>lower=None</em>, <em>upper=None</em>, <em>bounds='[)'</em>, <em>empty=False</em><big>)</big><a class="headerlink" href="#psycopg2.extras.Range" title="Permalink to this definition">¶</a></dt>
<dd><p>Python representation for a PostgreSQL <a class="reference external" href="http://www.postgresql.org/docs/current/static/rangetypes.html"><tt class="sql docutils literal"><span class="pre">range</span></tt></a> type.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>lower</strong> – lower bound for the range. <tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt> means unbound</li>
<li><strong>upper</strong> – upper bound for the range. <tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt> means unbound</li>
<li><strong>bounds</strong> – one of the literal strings <tt class="docutils literal"><span class="pre">()</span></tt>, <tt class="docutils literal"><span class="pre">[)</span></tt>, <tt class="docutils literal"><span class="pre">(]</span></tt>, <tt class="docutils literal"><span class="pre">[]</span></tt>,
representing whether the lower or upper bounds are included</li>
<li><strong>empty</strong> – if <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt>, the range is empty</li>
</ul>
</td>
</tr>
</tbody>
</table>
<p>This Python type is only used to pass and retrieve range values to and
from PostgreSQL and doesn’t attempt to replicate the PostgreSQL range
features: it doesn’t perform normalization and doesn’t implement all the
<a class="reference external" href="http://www.postgresql.org/docs/current/static/functions-range.html#RANGE-OPERATORS-TABLE">operators</a> supported by the database.</p>
<p><tt class="xref py py-obj docutils literal"><span class="pre">Range</span></tt> objects are immutable, hashable, and support the <tt class="docutils literal"><span class="pre">in</span></tt> operator
(checking if an element is within the range). They can be tested for
equivalence but not for ordering. Empty ranges evaluate to <tt class="xref py py-obj docutils literal"><span class="pre">False</span></tt> in
boolean context, nonempty evaluate to <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt>.</p>
<p>Although it is possible to instantiate <tt class="xref py py-obj docutils literal"><span class="pre">Range</span></tt> objects, the class doesn’t
have an adapter registered, so you cannot normally pass these instances as
query arguments. To use range objects as query arguments you can either
use one of the provided subclasses, such as <a class="reference internal" href="#psycopg2.extras.NumericRange" title="psycopg2.extras.NumericRange"><tt class="xref py py-obj docutils literal"><span class="pre">NumericRange</span></tt></a> or create a
custom subclass using <a class="reference internal" href="#psycopg2.extras.register_range" title="psycopg2.extras.register_range"><tt class="xref py py-obj docutils literal"><span class="pre">register_range()</span></tt></a>.</p>
<p>Object attributes:</p>
<dl class="attribute">
<dt id="psycopg2.extras.Range.isempty">
<tt class="descname">isempty</tt><a class="headerlink" href="#psycopg2.extras.Range.isempty" title="Permalink to this definition">¶</a></dt>
<dd><p><tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt> if the range is empty.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.Range.lower">
<tt class="descname">lower</tt><a class="headerlink" href="#psycopg2.extras.Range.lower" title="Permalink to this definition">¶</a></dt>
<dd><p>The lower bound of the range. <tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt> if empty or unbound.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.Range.upper">
<tt class="descname">upper</tt><a class="headerlink" href="#psycopg2.extras.Range.upper" title="Permalink to this definition">¶</a></dt>
<dd><p>The upper bound of the range. <tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt> if empty or unbound.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.Range.lower_inc">
<tt class="descname">lower_inc</tt><a class="headerlink" href="#psycopg2.extras.Range.lower_inc" title="Permalink to this definition">¶</a></dt>
<dd><p><tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt> if the lower bound is included in the range.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.Range.upper_inc">
<tt class="descname">upper_inc</tt><a class="headerlink" href="#psycopg2.extras.Range.upper_inc" title="Permalink to this definition">¶</a></dt>
<dd><p><tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt> if the upper bound is included in the range.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.Range.lower_inf">
<tt class="descname">lower_inf</tt><a class="headerlink" href="#psycopg2.extras.Range.lower_inf" title="Permalink to this definition">¶</a></dt>
<dd><p><tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt> if the range doesn’t have a lower bound.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.Range.upper_inf">
<tt class="descname">upper_inf</tt><a class="headerlink" href="#psycopg2.extras.Range.upper_inf" title="Permalink to this definition">¶</a></dt>
<dd><p><tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt> if the range doesn’t have an upper bound.</p>
</dd></dl>
</dd></dl>
<p>The following <a class="reference internal" href="#psycopg2.extras.Range" title="psycopg2.extras.Range"><tt class="xref py py-obj docutils literal"><span class="pre">Range</span></tt></a> subclasses map builtin PostgreSQL <tt class="sql docutils literal"><span class="pre">range</span></tt> types to
Python objects: they have an adapter registered so their instances can be
passed as query arguments. <tt class="sql docutils literal"><span class="pre">range</span></tt> values read from database queries are
automatically casted into instances of these classes.</p>
<dl class="class">
<dt id="psycopg2.extras.NumericRange">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">NumericRange</tt><big>(</big><em>lower=None</em>, <em>upper=None</em>, <em>bounds='[)'</em>, <em>empty=False</em><big>)</big><a class="headerlink" href="#psycopg2.extras.NumericRange" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference internal" href="#psycopg2.extras.Range" title="psycopg2.extras.Range"><tt class="xref py py-obj docutils literal"><span class="pre">Range</span></tt></a> suitable to pass Python numeric types to a PostgreSQL range.</p>
<p>PostgreSQL types <tt class="sql docutils literal"><span class="pre">int4range</span></tt>, <tt class="sql docutils literal"><span class="pre">int8range</span></tt>, <tt class="sql docutils literal"><span class="pre">numrange</span></tt> are
casted into <tt class="xref py py-obj docutils literal"><span class="pre">NumericRange</span></tt> instances.</p>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.DateRange">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">DateRange</tt><big>(</big><em>lower=None</em>, <em>upper=None</em>, <em>bounds='[)'</em>, <em>empty=False</em><big>)</big><a class="headerlink" href="#psycopg2.extras.DateRange" title="Permalink to this definition">¶</a></dt>
<dd><p>Represents <tt class="sql docutils literal"><span class="pre">daterange</span></tt> values.</p>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.DateTimeRange">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">DateTimeRange</tt><big>(</big><em>lower=None</em>, <em>upper=None</em>, <em>bounds='[)'</em>, <em>empty=False</em><big>)</big><a class="headerlink" href="#psycopg2.extras.DateTimeRange" title="Permalink to this definition">¶</a></dt>
<dd><p>Represents <tt class="sql docutils literal"><span class="pre">tsrange</span></tt> values.</p>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.DateTimeTZRange">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">DateTimeTZRange</tt><big>(</big><em>lower=None</em>, <em>upper=None</em>, <em>bounds='[)'</em>, <em>empty=False</em><big>)</big><a class="headerlink" href="#psycopg2.extras.DateTimeTZRange" title="Permalink to this definition">¶</a></dt>
<dd><p>Represents <tt class="sql docutils literal"><span class="pre">tstzrange</span></tt> values.</p>
</dd></dl>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">Python lacks a representation for <tt class="sql docutils literal"><span class="pre">infinity</span></tt> date so Psycopg converts
the value to <tt class="xref py py-obj docutils literal"><span class="pre">date.max</span></tt> and such. When written into the database these
dates will assume their literal value (e.g. <tt class="sql docutils literal"><span class="pre">9999-12-31</span></tt> instead of
<tt class="sql docutils literal"><span class="pre">infinity</span></tt>). Check <a class="reference internal" href="usage.html#infinite-dates-handling"><em>Infinite dates handling</em></a> for an example of
an alternative adapter to map <tt class="xref py py-obj docutils literal"><span class="pre">date.max</span></tt> to <tt class="sql docutils literal"><span class="pre">infinity</span></tt>. An
alternative dates adapter will be used automatically by the <a class="reference internal" href="#psycopg2.extras.DateRange" title="psycopg2.extras.DateRange"><tt class="xref py py-obj docutils literal"><span class="pre">DateRange</span></tt></a>
adapter and so on.</p>
</div>
<p>Custom <tt class="sql docutils literal"><span class="pre">range</span></tt> types (created with <a class="reference external" href="http://www.postgresql.org/docs/current/static/sql-createtype.html"><tt class="sql docutils literal"><span class="pre">CREATE</span> <span class="pre">TYPE</span></tt></a> <tt class="sql docutils literal"><span class="pre">...</span> <span class="pre">AS</span> <span class="pre">RANGE</span></tt>) can be
adapted to a custom <a class="reference internal" href="#psycopg2.extras.Range" title="psycopg2.extras.Range"><tt class="xref py py-obj docutils literal"><span class="pre">Range</span></tt></a> subclass:</p>
<dl class="function">
<dt id="psycopg2.extras.register_range">
<tt class="descclassname">psycopg2.extras.</tt><tt class="descname">register_range</tt><big>(</big><em>pgrange</em>, <em>pyrange</em>, <em>conn_or_curs</em>, <em>globally=False</em><big>)</big><a class="headerlink" href="#psycopg2.extras.register_range" title="Permalink to this definition">¶</a></dt>
<dd><p>Create and register an adapter and the typecasters to convert between
a PostgreSQL <a class="reference external" href="http://www.postgresql.org/docs/current/static/rangetypes.html"><tt class="sql docutils literal"><span class="pre">range</span></tt></a> type and a PostgreSQL <a class="reference internal" href="#psycopg2.extras.Range" title="psycopg2.extras.Range"><tt class="xref py py-obj docutils literal"><span class="pre">Range</span></tt></a> subclass.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>pgrange</strong> – the name of the PostgreSQL <tt class="sql docutils literal"><span class="pre">range</span></tt> type. Can be
schema-qualified</li>
<li><strong>pyrange</strong> – a <a class="reference internal" href="#psycopg2.extras.Range" title="psycopg2.extras.Range"><tt class="xref py py-obj docutils literal"><span class="pre">Range</span></tt></a> strict subclass, or just a name to give to a new
class</li>
<li><strong>conn_or_curs</strong> – a connection or cursor used to find the oid of the
range and its subtype; the typecaster is registered in a scope limited
to this object, unless <em>globally</em> is set to <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt></li>
<li><strong>globally</strong> – if <tt class="xref py py-obj docutils literal"><span class="pre">False</span></tt> (default) register the typecaster only on
<em>conn_or_curs</em>, otherwise register it globally</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first last"><a class="reference internal" href="#psycopg2.extras.RangeCaster" title="psycopg2.extras.RangeCaster"><tt class="xref py py-obj docutils literal"><span class="pre">RangeCaster</span></tt></a> instance responsible for the conversion</p>
</td>
</tr>
</tbody>
</table>
<p>If a string is passed to <em>pyrange</em>, a new <a class="reference internal" href="#psycopg2.extras.Range" title="psycopg2.extras.Range"><tt class="xref py py-obj docutils literal"><span class="pre">Range</span></tt></a> subclass is created
with such name and will be available as the <a class="reference internal" href="#psycopg2.extras.RangeCaster.range" title="psycopg2.extras.RangeCaster.range"><tt class="xref py py-obj docutils literal"><span class="pre">range</span></tt></a> attribute
of the returned <a class="reference internal" href="#psycopg2.extras.RangeCaster" title="psycopg2.extras.RangeCaster"><tt class="xref py py-obj docutils literal"><span class="pre">RangeCaster</span></tt></a> object.</p>
<p>The function queries the database on <em>conn_or_curs</em> to inspect the
<em>pgrange</em> type and raises <a class="reference internal" href="module.html#psycopg2.ProgrammingError" title="psycopg2.ProgrammingError"><tt class="xref py py-obj docutils literal"><span class="pre">ProgrammingError</span></tt></a> if the type is not
found. If querying the database is not advisable, use directly the
<a class="reference internal" href="#psycopg2.extras.RangeCaster" title="psycopg2.extras.RangeCaster"><tt class="xref py py-obj docutils literal"><span class="pre">RangeCaster</span></tt></a> class and register the adapter and typecasters using the
provided functions.</p>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.RangeCaster">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">RangeCaster</tt><big>(</big><em>pgrange</em>, <em>pyrange</em>, <em>oid</em>, <em>subtype_oid</em>, <em>array_oid=None</em><big>)</big><a class="headerlink" href="#psycopg2.extras.RangeCaster" title="Permalink to this definition">¶</a></dt>
<dd><p>Helper class to convert between <a class="reference internal" href="#psycopg2.extras.Range" title="psycopg2.extras.Range"><tt class="xref py py-obj docutils literal"><span class="pre">Range</span></tt></a> and PostgreSQL range types.</p>
<p>Objects of this class are usually created by <a class="reference internal" href="#psycopg2.extras.register_range" title="psycopg2.extras.register_range"><tt class="xref py py-obj docutils literal"><span class="pre">register_range()</span></tt></a>. Manual
creation could be useful if querying the database is not advisable: in
this case the oids must be provided.</p>
<p>Object attributes:</p>
<dl class="attribute">
<dt id="psycopg2.extras.RangeCaster.range">
<tt class="descname">range</tt><a class="headerlink" href="#psycopg2.extras.RangeCaster.range" title="Permalink to this definition">¶</a></dt>
<dd><p>The <tt class="xref py py-obj docutils literal"><span class="pre">Range</span></tt> subclass adapted.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.RangeCaster.adapter">
<tt class="descname">adapter</tt><a class="headerlink" href="#psycopg2.extras.RangeCaster.adapter" title="Permalink to this definition">¶</a></dt>
<dd><p>The <a class="reference internal" href="extensions.html#psycopg2.extensions.ISQLQuote" title="psycopg2.extensions.ISQLQuote"><tt class="xref py py-obj docutils literal"><span class="pre">ISQLQuote</span></tt></a> responsible to adapt <tt class="xref py py-obj docutils literal"><span class="pre">range</span></tt>.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.RangeCaster.typecaster">
<tt class="descname">typecaster</tt><a class="headerlink" href="#psycopg2.extras.RangeCaster.typecaster" title="Permalink to this definition">¶</a></dt>
<dd><p>The object responsible for casting.</p>
</dd></dl>
<dl class="attribute">
<dt id="psycopg2.extras.RangeCaster.array_typecaster">
<tt class="descname">array_typecaster</tt><a class="headerlink" href="#psycopg2.extras.RangeCaster.array_typecaster" title="Permalink to this definition">¶</a></dt>
<dd><p>The object responsible to cast arrays, if available, else <tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt>.</p>
</dd></dl>
</dd></dl>
</div>
<div class="section" id="uuid-data-type">
<span id="adapt-uuid"></span><span id="index-8"></span><h3>UUID data type<a class="headerlink" href="#uuid-data-type" title="Permalink to this headline">¶</a></h3>
<div class="versionadded">
<p><span>New in version 2.0.9.</span></p>
</div>
<div class="versionchanged">
<p><span>Changed in version 2.0.13: </span>added UUID array support.</p>
</div>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">psycopg2</span><span class="o">.</span><span class="n">extras</span><span class="o">.</span><span class="n">register_uuid</span><span class="p">()</span>
<span class="go"><psycopg2._psycopg.type object at 0x...></span>
<span class="gp">>>> </span><span class="c"># Python UUID can be used in SQL queries</span>
<span class="gp">>>> </span><span class="kn">import</span> <span class="nn">uuid</span>
<span class="gp">>>> </span><span class="n">my_uuid</span> <span class="o">=</span> <span class="n">uuid</span><span class="o">.</span><span class="n">UUID</span><span class="p">(</span><span class="s">'{12345678-1234-5678-1234-567812345678}'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">psycopg2</span><span class="o">.</span><span class="n">extensions</span><span class="o">.</span><span class="n">adapt</span><span class="p">(</span><span class="n">my_uuid</span><span class="p">)</span><span class="o">.</span><span class="n">getquoted</span><span class="p">()</span>
<span class="go">"'12345678-1234-5678-1234-567812345678'::uuid"</span>
<span class="gp">>>> </span><span class="c"># PostgreSQL UUID are transformed into Python UUID objects.</span>
<span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"SELECT 'a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'::uuid"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">fetchone</span><span class="p">()[</span><span class="mi">0</span><span class="p">]</span>
<span class="go">UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11')</span>
</pre></div>
</div>
<dl class="function">
<dt id="psycopg2.extras.register_uuid">
<tt class="descclassname">psycopg2.extras.</tt><tt class="descname">register_uuid</tt><big>(</big><em>oids=None</em>, <em>conn_or_curs=None</em><big>)</big><a class="headerlink" href="#psycopg2.extras.register_uuid" title="Permalink to this definition">¶</a></dt>
<dd><p>Create the UUID type and an uuid.UUID adapter.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>oids</strong> – oid for the PostgreSQL <tt class="sql docutils literal"><span class="pre">uuid</span></tt> type, or 2-items sequence
with oids of the type and the array. If not specified, use PostgreSQL
standard oids.</li>
<li><strong>conn_or_curs</strong> – where to register the typecaster. If not specified,
register it globally.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.UUID_adapter">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">UUID_adapter</tt><big>(</big><em>uuid</em><big>)</big><a class="headerlink" href="#psycopg2.extras.UUID_adapter" title="Permalink to this definition">¶</a></dt>
<dd><p>Adapt Python’s <a class="reference external" href="http://docs.python.org/library/uuid.html">uuid.UUID</a> type to PostgreSQL’s <a class="reference external" href="http://www.postgresql.org/docs/current/static/datatype-uuid.html">uuid</a>.</p>
</dd></dl>
</div>
<div class="section" id="inet-data-type">
<span id="index-9"></span><h3><tt class="sql docutils literal"><span class="pre">inet</span></tt> data type<a class="headerlink" href="#inet-data-type" title="Permalink to this headline">¶</a></h3>
<div class="versionadded">
<p><span>New in version 2.0.9.</span></p>
</div>
<div class="versionchanged">
<p><span>Changed in version 2.4.5: </span>added inet array support.</p>
</div>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">psycopg2</span><span class="o">.</span><span class="n">extras</span><span class="o">.</span><span class="n">register_inet</span><span class="p">()</span>
<span class="go"><psycopg2._psycopg.type object at 0x...></span>
<span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">mogrify</span><span class="p">(</span><span class="s">"SELECT </span><span class="si">%s</span><span class="s">"</span><span class="p">,</span> <span class="p">(</span><span class="n">Inet</span><span class="p">(</span><span class="s">'127.0.0.1/32'</span><span class="p">),))</span>
<span class="go">"SELECT E'127.0.0.1/32'::inet"</span>
<span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s">"SELECT '192.168.0.1/24'::inet"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">cur</span><span class="o">.</span><span class="n">fetchone</span><span class="p">()[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">addr</span>
<span class="go">'192.168.0.1/24'</span>
</pre></div>
</div>
<dl class="function">
<dt id="psycopg2.extras.register_inet">
<tt class="descclassname">psycopg2.extras.</tt><tt class="descname">register_inet</tt><big>(</big><em>oid=None</em>, <em>conn_or_curs=None</em><big>)</big><a class="headerlink" href="#psycopg2.extras.register_inet" title="Permalink to this definition">¶</a></dt>
<dd><p>Create the INET type and an Inet adapter.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>oid</strong> – oid for the PostgreSQL <tt class="sql docutils literal"><span class="pre">inet</span></tt> type, or 2-items sequence
with oids of the type and the array. If not specified, use PostgreSQL
standard oids.</li>
<li><strong>conn_or_curs</strong> – where to register the typecaster. If not specified,
register it globally.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="class">
<dt id="psycopg2.extras.Inet">
<em class="property">class </em><tt class="descclassname">psycopg2.extras.</tt><tt class="descname">Inet</tt><big>(</big><em>addr</em><big>)</big><a class="headerlink" href="#psycopg2.extras.Inet" title="Permalink to this definition">¶</a></dt>
<dd><p>Wrap a string to allow for correct SQL-quoting of inet values.</p>
<p>Note that this adapter does NOT check the passed value to make
sure it really is an inet-compatible address but DOES call adapt()
on it to make sure it is impossible to execute an SQL-injection
by passing an evil value to the initializer.</p>
</dd></dl>
</div>
</div>
<div class="section" id="fractional-time-zones">
<span id="index-10"></span><h2>Fractional time zones<a class="headerlink" href="#fractional-time-zones" title="Permalink to this headline">¶</a></h2>
<dl class="function">
<dt id="psycopg2.extras.register_tstz_w_secs">
<tt class="descclassname">psycopg2.extras.</tt><tt class="descname">register_tstz_w_secs</tt><big>(</big><em>oids=None</em>, <em>conn_or_curs=None</em><big>)</big><a class="headerlink" href="#psycopg2.extras.register_tstz_w_secs" title="Permalink to this definition">¶</a></dt>
<dd><p>The function used to register an alternate type caster for
<tt class="sql docutils literal"><span class="pre">TIMESTAMP</span> <span class="pre">WITH</span> <span class="pre">TIME</span> <span class="pre">ZONE</span></tt> to deal with historical time zones with
seconds in the UTC offset.</p>
<p>These are now correctly handled by the default type caster, so currently
the function doesn’t do anything.</p>
<div class="versionadded">
<p><span>New in version 2.0.9.</span></p>
</div>
<div class="versionchanged">
<p><span>Changed in version 2.2.2: </span>function is no-op: see <a class="reference internal" href="usage.html#tz-handling"><em>Time zones handling</em></a>.</p>
</div>
</dd></dl>
</div>
<div class="section" id="coroutine-support">
<span id="index-11"></span><h2>Coroutine support<a class="headerlink" href="#coroutine-support" title="Permalink to this headline">¶</a></h2>
<dl class="function">
<dt id="psycopg2.extras.wait_select">
<tt class="descclassname">psycopg2.extras.</tt><tt class="descname">wait_select</tt><big>(</big><em>conn</em><big>)</big><a class="headerlink" href="#psycopg2.extras.wait_select" title="Permalink to this definition">¶</a></dt>
<dd><p>Wait until a connection or cursor has data available.</p>
<p>The function is an example of a wait callback to be registered with
<a class="reference internal" href="extensions.html#psycopg2.extensions.set_wait_callback" title="psycopg2.extensions.set_wait_callback"><tt class="xref py py-obj docutils literal"><span class="pre">set_wait_callback()</span></tt></a>. This function uses
<a class="reference external" href="http://docs.python.org/3.2/library/select.html#select.select" title="(in Python v3.2)"><tt class="xref py py-func docutils literal"><span class="pre">select()</span></tt></a> to wait for data available.</p>
</dd></dl>
</div>
</div>
</div>
</div>
</div>
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<div class="sphinxsidebarwrapper">
<h3><a href="index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#"><tt class="docutils literal"><span class="pre">psycopg2.extras</span></tt> – Miscellaneous goodies for Psycopg 2</a><ul>
<li><a class="reference internal" href="#connection-and-cursor-subclasses">Connection and cursor subclasses</a><ul>
<li><a class="reference internal" href="#dictionary-like-cursor">Dictionary-like cursor</a></li>
<li><a class="reference internal" href="#real-dictionary-cursor">Real dictionary cursor</a></li>
<li><a class="reference internal" href="#namedtuple-cursor"><tt class="docutils literal"><span class="pre">namedtuple</span></tt> cursor</a></li>
<li><a class="reference internal" href="#logging-cursor">Logging cursor</a></li>
</ul>
</li>
<li><a class="reference internal" href="#additional-data-types">Additional data types</a><ul>
<li><a class="reference internal" href="#json-adaptation">JSON adaptation</a></li>
<li><a class="reference internal" href="#hstore-data-type">Hstore data type</a></li>
<li><a class="reference internal" href="#composite-types-casting">Composite types casting</a></li>
<li><a class="reference internal" href="#range-data-types">Range data types</a></li>
<li><a class="reference internal" href="#uuid-data-type">UUID data type</a></li>
<li><a class="reference internal" href="#inet-data-type"><tt class="sql docutils literal"><span class="pre">inet</span></tt> data type</a></li>
</ul>
</li>
<li><a class="reference internal" href="#fractional-time-zones">Fractional time zones</a></li>
<li><a class="reference internal" href="#coroutine-support">Coroutine support</a></li>
</ul>
</li>
</ul>
<h4>Previous topic</h4>
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<h4>Next topic</h4>
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title="next chapter"><tt class="docutils literal docutils literal docutils literal"><span class="pre">psycopg2.errorcodes</span></tt> – Error codes defined by PostgreSQL</a></p>
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