<!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="X-UA-Compatible" content="IE=Edge" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>PostgreSQL specific lookups — Django 1.11.20 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" id="documentation_options" data-url_root="../../../" src="../../../_static/documentation_options.js"></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>
<script type="text/javascript" src="../../../_static/language_data.js"></script>
<link rel="index" title="Index" href="../../../genindex.html" />
<link rel="search" title="Search" href="../../../search.html" />
<link rel="next" title="Database migration operations" href="operations.html" />
<link rel="prev" title="PostgreSQL specific model indexes" href="indexes.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>
<div class="document">
<div id="custom-doc" class="yui-t6">
<div id="hd">
<h1><a href="../../../index.html">Django 1.11.20 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="indexes.html" title="PostgreSQL specific model indexes">previous</a>
|
<a href="../../index.html" title="API Reference" accesskey="U">up</a>
|
<a href="operations.html" title="Database migration operations">next</a> »</div>
</div>
<div id="bd">
<div id="yui-main">
<div class="yui-b">
<div class="yui-g" id="ref-contrib-postgres-lookups">
<div class="section" id="s-postgresql-specific-lookups">
<span id="postgresql-specific-lookups"></span><h1>PostgreSQL specific lookups<a class="headerlink" href="#postgresql-specific-lookups" title="Permalink to this headline">¶</a></h1>
<div class="section" id="s-trigram-similarity">
<span id="trigram-similarity"></span><h2>Trigram similarity<a class="headerlink" href="#trigram-similarity" title="Permalink to this headline">¶</a></h2>
<div class="versionadded" id="std:fieldlookup-trigram_similar">
<span class="title">New in Django 1.10.</span> </div>
<p>The <code class="docutils literal notranslate"><span class="pre">trigram_similar</span></code> lookup allows you to perform trigram lookups,
measuring the number of trigrams (three consecutive characters) shared, using a
dedicated PostgreSQL extension. A trigram lookup is given an expression and
returns results that have a similarity measurement greater than the current
similarity threshold.</p>
<p>To use it, add <code class="docutils literal notranslate"><span class="pre">'django.contrib.postgres'</span></code> in your <a class="reference internal" href="../../settings.html#std:setting-INSTALLED_APPS"><code class="xref std std-setting docutils literal notranslate"><span class="pre">INSTALLED_APPS</span></code></a>
and activate the <a class="reference external" href="https://www.postgresql.org/docs/current/static/pgtrgm.html">pg_trgm extension</a> on
PostgreSQL. You can install the extension using the
<a class="reference internal" href="operations.html#django.contrib.postgres.operations.TrigramExtension" title="django.contrib.postgres.operations.TrigramExtension"><code class="xref py py-class docutils literal notranslate"><span class="pre">TrigramExtension</span></code></a> migration
operation.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">trigram_similar</span></code> lookup can be used on
<a class="reference internal" href="../../models/fields.html#django.db.models.CharField" title="django.db.models.CharField"><code class="xref py py-class docutils literal notranslate"><span class="pre">CharField</span></code></a> and <a class="reference internal" href="../../models/fields.html#django.db.models.TextField" title="django.db.models.TextField"><code class="xref py py-class docutils literal notranslate"><span class="pre">TextField</span></code></a>:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">City</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">name__trigram_similar</span><span class="o">=</span><span class="s2">"Middlesborough"</span><span class="p">)</span>
<span class="go">['<City: Middlesbrough>']</span>
</pre></div>
</div>
</div>
<div class="section" id="s-unaccent">
<span id="unaccent"></span><h2><code class="docutils literal notranslate"><span class="pre">Unaccent</span></code><a class="headerlink" href="#unaccent" title="Permalink to this headline">¶</a></h2>
<p id="std:fieldlookup-unaccent">The <code class="docutils literal notranslate"><span class="pre">unaccent</span></code> lookup allows you to perform accent-insensitive lookups using
a dedicated PostgreSQL extension.</p>
<p>This lookup is implemented using <a class="reference internal" href="../../models/lookups.html#django.db.models.Transform" title="django.db.models.Transform"><code class="xref py py-class docutils literal notranslate"><span class="pre">Transform</span></code></a>, so it
can be chained with other lookup functions. To use it, you need to add
<code class="docutils literal notranslate"><span class="pre">'django.contrib.postgres'</span></code> in your <a class="reference internal" href="../../settings.html#std:setting-INSTALLED_APPS"><code class="xref std std-setting docutils literal notranslate"><span class="pre">INSTALLED_APPS</span></code></a> and activate
the <a class="reference external" href="https://www.postgresql.org/docs/current/static/unaccent.html">unaccent extension on PostgreSQL</a>. The
<a class="reference internal" href="operations.html#django.contrib.postgres.operations.UnaccentExtension" title="django.contrib.postgres.operations.UnaccentExtension"><code class="xref py py-class docutils literal notranslate"><span class="pre">UnaccentExtension</span></code></a> migration
operation is available if you want to perform this activation using migrations).</p>
<p>The <code class="docutils literal notranslate"><span class="pre">unaccent</span></code> lookup can be used on
<a class="reference internal" href="../../models/fields.html#django.db.models.CharField" title="django.db.models.CharField"><code class="xref py py-class docutils literal notranslate"><span class="pre">CharField</span></code></a> and <a class="reference internal" href="../../models/fields.html#django.db.models.TextField" title="django.db.models.TextField"><code class="xref py py-class docutils literal notranslate"><span class="pre">TextField</span></code></a>:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">City</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">name__unaccent</span><span class="o">=</span><span class="s2">"México"</span><span class="p">)</span>
<span class="go">['<City: Mexico>']</span>
<span class="gp">>>> </span><span class="n">User</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">first_name__unaccent__startswith</span><span class="o">=</span><span class="s2">"Jerem"</span><span class="p">)</span>
<span class="go">['<User: Jeremy>', '<User: Jérémy>', '<User: Jérémie>', '<User: Jeremie>']</span>
</pre></div>
</div>
<div class="admonition warning">
<p class="first admonition-title">Warning</p>
<p class="last"><code class="docutils literal notranslate"><span class="pre">unaccent</span></code> lookups should perform fine in most use cases. However, queries
using this filter will generally perform full table scans, which can be slow
on large tables. In those cases, using dedicated full text indexing tools
might be appropriate.</p>
</div>
</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="#">PostgreSQL specific lookups</a><ul>
<li><a class="reference internal" href="#trigram-similarity">Trigram similarity</a></li>
<li><a class="reference internal" href="#unaccent"><code class="docutils literal notranslate"><span class="pre">Unaccent</span></code></a></li>
</ul>
</li>
</ul>
<h4>Previous topic</h4>
<p class="topless"><a href="indexes.html"
title="previous chapter">PostgreSQL specific model indexes</a></p>
<h4>Next topic</h4>
<p class="topless"><a href="operations.html"
title="next chapter">Database migration operations</a></p>
<div role="note" aria-label="source link">
<h3>This Page</h3>
<ul class="this-page-menu">
<li><a href="../../../_sources/ref/contrib/postgres/lookups.txt"
rel="nofollow">Show Source</a></li>
</ul>
</div>
<div id="searchbox" style="display: none" role="search">
<h3>Quick search</h3>
<div class="searchformwrapper">
<form class="search" action="../../../search.html" method="get">
<input type="text" name="q" />
<input type="submit" value="Go" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
</div>
<script type="text/javascript">$('#searchbox').show(0);</script>
</div>
</div>
<h3>Last update:</h3>
<p class="topless">Feb 11, 2019</p>
</div>
</div>
<div id="ft">
<div class="nav">
« <a href="indexes.html" title="PostgreSQL specific model indexes">previous</a>
|
<a href="../../index.html" title="API Reference" accesskey="U">up</a>
|
<a href="operations.html" title="Database migration operations">next</a> »</div>
</div>
</div>
<div class="clearer"></div>
</div>
</body>
</html>
