<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" lang=""> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Migration Operations — Django 1.8.19 documentation</title> <link rel="stylesheet" href="../_static/default.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../', VERSION: '1.8.19', COLLAPSE_INDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true }; </script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <link rel="index" title="Index" href="../genindex.html" /> <link rel="search" title="Search" href="../search.html" /> <link rel="top" title="Django 1.8.19 documentation" href="../contents.html" /> <link rel="up" title="API Reference" href="index.html" /> <link rel="next" title="Models" href="models/index.html" /> <link rel="prev" title="Middleware" href="middleware.html" /> <script type="text/javascript" src="../templatebuiltins.js"></script> <script type="text/javascript"> (function($) { if (!django_template_builtins) { // templatebuiltins.js missing, do nothing. return; } $(document).ready(function() { // Hyperlink Django template tags and filters var base = "templates/builtins.html"; if (base == "#") { // Special case for builtins.html itself base = ""; } // Tags are keywords, class '.k' $("div.highlight\\-html\\+django span.k").each(function(i, elem) { var tagname = $(elem).text(); if ($.inArray(tagname, django_template_builtins.ttags) != -1) { var fragment = tagname.replace(/_/, '-'); $(elem).html("<a href='" + base + "#" + fragment + "'>" + tagname + "</a>"); } }); // Filters are functions, class '.nf' $("div.highlight\\-html\\+django span.nf").each(function(i, elem) { var filtername = $(elem).text(); if ($.inArray(filtername, django_template_builtins.tfilters) != -1) { var fragment = filtername.replace(/_/, '-'); $(elem).html("<a href='" + base + "#" + fragment + "'>" + filtername + "</a>"); } }); }); })(jQuery); </script> </head> <body role="document"> <div class="document"> <div id="custom-doc" class="yui-t6"> <div id="hd"> <h1><a href="../index.html">Django 1.8.19 documentation</a></h1> <div id="global-nav"> <a title="Home page" href="../index.html">Home</a> | <a title="Table of contents" href="../contents.html">Table of contents</a> | <a title="Global index" href="../genindex.html">Index</a> | <a title="Module index" href="../py-modindex.html">Modules</a> </div> <div class="nav"> « <a href="middleware.html" title="Middleware">previous</a> | <a href="index.html" title="API Reference" accesskey="U">up</a> | <a href="models/index.html" title="Models">next</a> »</div> </div> <div id="bd"> <div id="yui-main"> <div class="yui-b"> <div class="yui-g" id="ref-migration-operations"> <div class="section" id="s-module-django.db.migrations.operations"> <span id="s-migration-operations"></span><span id="module-django.db.migrations.operations"></span><span id="migration-operations"></span><h1>Migration Operations<a class="headerlink" href="#module-django.db.migrations.operations" title="Permalink to this headline">¶</a></h1> <p>Migration files are composed of one or more <code class="docutils literal"><span class="pre">Operation</span></code>s, objects that declaratively record what the migration should do to your database.</p> <p>Django also uses these <code class="docutils literal"><span class="pre">Operation</span></code> objects to work out what your models looked like historically, and to calculate what changes you’ve made to your models since the last migration so it can automatically write your migrations; that’s why they’re declarative, as it means Django can easily load them all into memory and run through them without touching the database to work out what your project should look like.</p> <p>There are also more specialized <code class="docutils literal"><span class="pre">Operation</span></code> objects which are for things like <a class="reference internal" href="../topics/migrations.html#data-migrations"><span class="std std-ref">data migrations</span></a> and for advanced manual database manipulation. You can also write your own <code class="docutils literal"><span class="pre">Operation</span></code> classes if you want to encapsulate a custom change you commonly make.</p> <p>If you need an empty migration file to write your own <code class="docutils literal"><span class="pre">Operation</span></code> objects into, just use <code class="docutils literal"><span class="pre">python</span> <span class="pre">manage.py</span> <span class="pre">makemigrations</span> <span class="pre">--empty</span> <span class="pre">yourappname</span></code>, but be aware that manually adding schema-altering operations can confuse the migration autodetector and make resulting runs of <a class="reference internal" href="django-admin.html#django-admin-makemigrations"><code class="xref std std-djadmin docutils literal"><span class="pre">makemigrations</span></code></a> output incorrect code.</p> <p>All of the core Django operations are available from the <code class="docutils literal"><span class="pre">django.db.migrations.operations</span></code> module.</p> <p>For introductory material, see the <a class="reference internal" href="../topics/migrations.html"><span class="doc">migrations topic guide</span></a>.</p> <div class="section" id="s-schema-operations"> <span id="schema-operations"></span><h2>Schema Operations<a class="headerlink" href="#schema-operations" title="Permalink to this headline">¶</a></h2> <div class="section" id="s-createmodel"> <span id="createmodel"></span><h3>CreateModel<a class="headerlink" href="#createmodel" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.CreateModel"> <em class="property">class </em><code class="descname">CreateModel</code>(<em>name</em>, <em>fields</em>, <em>options=None</em>, <em>bases=None</em>, <em>managers=None</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/models.html#CreateModel"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.CreateModel" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Creates a new model in the project history and a corresponding table in the database to match it.</p> <p><code class="docutils literal"><span class="pre">name</span></code> is the model name, as would be written in the <code class="docutils literal"><span class="pre">models.py</span></code> file.</p> <p><code class="docutils literal"><span class="pre">fields</span></code> is a list of 2-tuples of <code class="docutils literal"><span class="pre">(field_name,</span> <span class="pre">field_instance)</span></code>. The field instance should be an unbound field (so just <code class="docutils literal"><span class="pre">models.CharField(...)</span></code>, rather than a field taken from another model).</p> <p><code class="docutils literal"><span class="pre">options</span></code> is an optional dictionary of values from the model’s <code class="docutils literal"><span class="pre">Meta</span></code> class.</p> <p><code class="docutils literal"><span class="pre">bases</span></code> is an optional list of other classes to have this model inherit from; it can contain both class objects as well as strings in the format <code class="docutils literal"><span class="pre">"appname.ModelName"</span></code> if you want to depend on another model (so you inherit from the historical version). If it’s not supplied, it defaults to just inheriting from the standard <code class="docutils literal"><span class="pre">models.Model</span></code>.</p> <p><code class="docutils literal"><span class="pre">managers</span></code> takes a list of 2-tuples of <code class="docutils literal"><span class="pre">(manager_name,</span> <span class="pre">manager_instance)</span></code>. The first manager in the list will be the default manager for this model during migrations.</p> <div class="versionchanged"> <span class="title">Changed in Django 1.8:</span> <p>The <code class="docutils literal"><span class="pre">managers</span></code> argument was added.</p> </div> </div> <div class="section" id="s-deletemodel"> <span id="deletemodel"></span><h3>DeleteModel<a class="headerlink" href="#deletemodel" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.DeleteModel"> <em class="property">class </em><code class="descname">DeleteModel</code>(<em>name</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/models.html#DeleteModel"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.DeleteModel" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Deletes the model from the project history and its table from the database.</p> </div> <div class="section" id="s-renamemodel"> <span id="renamemodel"></span><h3>RenameModel<a class="headerlink" href="#renamemodel" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.RenameModel"> <em class="property">class </em><code class="descname">RenameModel</code>(<em>old_name</em>, <em>new_name</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/models.html#RenameModel"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.RenameModel" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Renames the model from an old name to a new one.</p> <p>You may have to manually add this if you change the model’s name and quite a few of its fields at once; to the autodetector, this will look like you deleted a model with the old name and added a new one with a different name, and the migration it creates will lose any data in the old table.</p> </div> <div class="section" id="s-altermodeltable"> <span id="altermodeltable"></span><h3>AlterModelTable<a class="headerlink" href="#altermodeltable" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.AlterModelTable"> <em class="property">class </em><code class="descname">AlterModelTable</code>(<em>name</em>, <em>table</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/models.html#AlterModelTable"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.AlterModelTable" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Changes the model’s table name (the <a class="reference internal" href="models/options.html#django.db.models.Options.db_table" title="django.db.models.Options.db_table"><code class="xref py py-attr docutils literal"><span class="pre">db_table</span></code></a> option on the <code class="docutils literal"><span class="pre">Meta</span></code> subclass).</p> </div> <div class="section" id="s-alteruniquetogether"> <span id="alteruniquetogether"></span><h3>AlterUniqueTogether<a class="headerlink" href="#alteruniquetogether" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.AlterUniqueTogether"> <em class="property">class </em><code class="descname">AlterUniqueTogether</code>(<em>name</em>, <em>unique_together</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/models.html#AlterUniqueTogether"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.AlterUniqueTogether" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Changes the model’s set of unique constraints (the <a class="reference internal" href="models/options.html#django.db.models.Options.unique_together" title="django.db.models.Options.unique_together"><code class="xref py py-attr docutils literal"><span class="pre">unique_together</span></code></a> option on the <code class="docutils literal"><span class="pre">Meta</span></code> subclass).</p> </div> <div class="section" id="s-alterindextogether"> <span id="alterindextogether"></span><h3>AlterIndexTogether<a class="headerlink" href="#alterindextogether" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.AlterIndexTogether"> <em class="property">class </em><code class="descname">AlterIndexTogether</code>(<em>name</em>, <em>index_together</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/models.html#AlterIndexTogether"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.AlterIndexTogether" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Changes the model’s set of custom indexes (the <a class="reference internal" href="models/options.html#django.db.models.Options.index_together" title="django.db.models.Options.index_together"><code class="xref py py-attr docutils literal"><span class="pre">index_together</span></code></a> option on the <code class="docutils literal"><span class="pre">Meta</span></code> subclass).</p> </div> <div class="section" id="s-alterorderwithrespectto"> <span id="alterorderwithrespectto"></span><h3>AlterOrderWithRespectTo<a class="headerlink" href="#alterorderwithrespectto" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.AlterOrderWithRespectTo"> <em class="property">class </em><code class="descname">AlterOrderWithRespectTo</code>(<em>name</em>, <em>order_with_respect_to</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/models.html#AlterOrderWithRespectTo"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.AlterOrderWithRespectTo" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Makes or deletes the <code class="docutils literal"><span class="pre">_order</span></code> column needed for the <a class="reference internal" href="models/options.html#django.db.models.Options.order_with_respect_to" title="django.db.models.Options.order_with_respect_to"><code class="xref py py-attr docutils literal"><span class="pre">order_with_respect_to</span></code></a> option on the <code class="docutils literal"><span class="pre">Meta</span></code> subclass.</p> </div> <div class="section" id="s-altermodeloptions"> <span id="altermodeloptions"></span><h3>AlterModelOptions<a class="headerlink" href="#altermodeloptions" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.AlterModelOptions"> <em class="property">class </em><code class="descname">AlterModelOptions</code>(<em>name</em>, <em>options</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/models.html#AlterModelOptions"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.AlterModelOptions" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Stores changes to miscellaneous model options (settings on a model’s <code class="docutils literal"><span class="pre">Meta</span></code>) like <code class="docutils literal"><span class="pre">permissions</span></code> and <code class="docutils literal"><span class="pre">verbose_name</span></code>. Does not affect the database, but persists these changes for <a class="reference internal" href="#django.db.migrations.operations.RunPython" title="django.db.migrations.operations.RunPython"><code class="xref py py-class docutils literal"><span class="pre">RunPython</span></code></a> instances to use. <code class="docutils literal"><span class="pre">options</span></code> should be a dictionary mapping option names to values.</p> </div> <div class="section" id="s-altermodelmanagers"> <span id="altermodelmanagers"></span><h3>AlterModelManagers<a class="headerlink" href="#altermodelmanagers" title="Permalink to this headline">¶</a></h3> <div class="versionadded"> <span class="title">New in Django 1.8.</span> </div> <dl class="class"> <dt id="django.db.migrations.operations.AlterModelManagers"> <em class="property">class </em><code class="descname">AlterModelManagers</code>(<em>name</em>, <em>managers</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/models.html#AlterModelManagers"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.AlterModelManagers" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Alters the managers that are available during migrations.</p> </div> <div class="section" id="s-addfield"> <span id="addfield"></span><h3>AddField<a class="headerlink" href="#addfield" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.AddField"> <em class="property">class </em><code class="descname">AddField</code>(<em>model_name</em>, <em>name</em>, <em>field</em>, <em>preserve_default=True</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/fields.html#AddField"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.AddField" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Adds a field to a model. <code class="docutils literal"><span class="pre">model_name</span></code> is the model’s name, <code class="docutils literal"><span class="pre">name</span></code> is the field’s name, and <code class="docutils literal"><span class="pre">field</span></code> is an unbound Field instance (the thing you would put in the field declaration in <code class="docutils literal"><span class="pre">models.py</span></code> - for example, <code class="docutils literal"><span class="pre">models.IntegerField(null=True)</span></code>.</p> <p>The <code class="docutils literal"><span class="pre">preserve_default</span></code> argument indicates whether the field’s default value is permanent and should be baked into the project state (<code class="docutils literal"><span class="pre">True</span></code>), or if it is temporary and just for this migration (<code class="docutils literal"><span class="pre">False</span></code>) - usually because the migration is adding a non-nullable field to a table and needs a default value to put into existing rows. It does not affect the behavior of setting defaults in the database directly - Django never sets database defaults and always applies them in the Django ORM code.</p> </div> <div class="section" id="s-removefield"> <span id="removefield"></span><h3>RemoveField<a class="headerlink" href="#removefield" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.RemoveField"> <em class="property">class </em><code class="descname">RemoveField</code>(<em>model_name</em>, <em>name</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/fields.html#RemoveField"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.RemoveField" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Removes a field from a model.</p> <p>Bear in mind that when reversed this is actually adding a field to a model; if the field is not nullable this may make this operation irreversible (apart from any data loss, which of course is irreversible).</p> </div> <div class="section" id="s-alterfield"> <span id="alterfield"></span><h3>AlterField<a class="headerlink" href="#alterfield" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.AlterField"> <em class="property">class </em><code class="descname">AlterField</code>(<em>model_name</em>, <em>name</em>, <em>field</em>, <em>preserve_default=True</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/fields.html#AlterField"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.AlterField" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Alters a field’s definition, including changes to its type, <a class="reference internal" href="models/fields.html#django.db.models.Field.null" title="django.db.models.Field.null"><code class="xref py py-attr docutils literal"><span class="pre">null</span></code></a>, <a class="reference internal" href="models/fields.html#django.db.models.Field.unique" title="django.db.models.Field.unique"><code class="xref py py-attr docutils literal"><span class="pre">unique</span></code></a>, <a class="reference internal" href="models/fields.html#django.db.models.Field.db_column" title="django.db.models.Field.db_column"><code class="xref py py-attr docutils literal"><span class="pre">db_column</span></code></a> and other field attributes.</p> <p>The <code class="docutils literal"><span class="pre">preserve_default</span></code> argument indicates whether the field’s default value is permanent and should be baked into the project state (<code class="docutils literal"><span class="pre">True</span></code>), or if it is temporary and just for this migration (<code class="docutils literal"><span class="pre">False</span></code>) - usually because the migration is altering a nullable field to a non-nullable one and needs a default value to put into existing rows. It does not affect the behavior of setting defaults in the database directly - Django never sets database defaults and always applies them in the Django ORM code.</p> <p>Note that not all changes are possible on all databases - for example, you cannot change a text-type field like <code class="docutils literal"><span class="pre">models.TextField()</span></code> into a number-type field like <code class="docutils literal"><span class="pre">models.IntegerField()</span></code> on most databases.</p> <div class="versionchanged"> <span class="title">Changed in Django 1.7.1:</span> <p>The <code class="docutils literal"><span class="pre">preserve_default</span></code> argument was added.</p> </div> </div> <div class="section" id="s-renamefield"> <span id="renamefield"></span><h3>RenameField<a class="headerlink" href="#renamefield" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.RenameField"> <em class="property">class </em><code class="descname">RenameField</code>(<em>model_name</em>, <em>old_name</em>, <em>new_name</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/fields.html#RenameField"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.RenameField" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Changes a field’s name (and, unless <a class="reference internal" href="models/fields.html#django.db.models.Field.db_column" title="django.db.models.Field.db_column"><code class="xref py py-attr docutils literal"><span class="pre">db_column</span></code></a> is set, its column name).</p> </div> </div> <div class="section" id="s-special-operations"> <span id="special-operations"></span><h2>Special Operations<a class="headerlink" href="#special-operations" title="Permalink to this headline">¶</a></h2> <div class="section" id="s-runsql"> <span id="runsql"></span><h3>RunSQL<a class="headerlink" href="#runsql" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.RunSQL"> <em class="property">class </em><code class="descname">RunSQL</code>(<em>sql</em>, <em>reverse_sql=None</em>, <em>state_operations=None</em>, <em>hints=None</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/special.html#RunSQL"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.RunSQL" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Allows running of arbitrary SQL on the database - useful for more advanced features of database backends that Django doesn’t support directly, like partial indexes.</p> <p><code class="docutils literal"><span class="pre">sql</span></code>, and <code class="docutils literal"><span class="pre">reverse_sql</span></code> if provided, should be strings of SQL to run on the database. On most database backends (all but PostgreSQL), Django will split the SQL into individual statements prior to executing them. This requires installing the <a class="reference external" href="https://pypi.python.org/pypi/sqlparse">sqlparse</a> Python library.</p> <p>You can also pass a list of strings or 2-tuples. The latter is used for passing queries and parameters in the same way as <a class="reference internal" href="../topics/db/sql.html#executing-custom-sql"><span class="std std-ref">cursor.execute()</span></a>. These three operations are equivalent:</p> <div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">migrations</span><span class="o">.</span><span class="n">RunSQL</span><span class="p">(</span><span class="s2">"INSERT INTO musician (name) VALUES ('Reinhardt');"</span><span class="p">)</span> <span class="n">migrations</span><span class="o">.</span><span class="n">RunSQL</span><span class="p">([(</span><span class="s2">"INSERT INTO musician (name) VALUES ('Reinhardt');"</span><span class="p">,</span> <span class="kc">None</span><span class="p">)])</span> <span class="n">migrations</span><span class="o">.</span><span class="n">RunSQL</span><span class="p">([(</span><span class="s2">"INSERT INTO musician (name) VALUES (</span><span class="si">%s</span><span class="s2">);"</span><span class="p">,</span> <span class="p">[</span><span class="s1">'Reinhardt'</span><span class="p">])])</span> </pre></div> </div> <p>If you want to include literal percent signs in the query, you have to double them if you are passing parameters.</p> <p>The <code class="docutils literal"><span class="pre">reverse_sql</span></code> queries are executed when the migration is unapplied, so you can reverse the changes done in the forwards queries:</p> <div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">migrations</span><span class="o">.</span><span class="n">RunSQL</span><span class="p">(</span> <span class="p">[(</span><span class="s2">"INSERT INTO musician (name) VALUES (</span><span class="si">%s</span><span class="s2">);"</span><span class="p">,</span> <span class="p">[</span><span class="s1">'Reinhardt'</span><span class="p">])],</span> <span class="p">[(</span><span class="s2">"DELETE FROM musician where name=</span><span class="si">%s</span><span class="s2">;"</span><span class="p">,</span> <span class="p">[</span><span class="s1">'Reinhardt'</span><span class="p">])],</span> <span class="p">)</span> </pre></div> </div> <p>The <code class="docutils literal"><span class="pre">state_operations</span></code> argument is so you can supply operations that are equivalent to the SQL in terms of project state; for example, if you are manually creating a column, you should pass in a list containing an <code class="docutils literal"><span class="pre">AddField</span></code> operation here so that the autodetector still has an up-to-date state of the model (otherwise, when you next run <code class="docutils literal"><span class="pre">makemigrations</span></code>, it won’t see any operation that adds that field and so will try to run it again).</p> <p>The optional <code class="docutils literal"><span class="pre">hints</span></code> argument will be passed as <code class="docutils literal"><span class="pre">**hints</span></code> to the <a class="reference internal" href="../topics/db/multi-db.html#allow_migrate" title="allow_migrate"><code class="xref py py-meth docutils literal"><span class="pre">allow_migrate()</span></code></a> method of database routers to assist them in making routing decisions. See <a class="reference internal" href="../topics/db/multi-db.html#topics-db-multi-db-hints"><span class="std std-ref">Hints</span></a> for more details on database hints.</p> <div class="versionchanged"> <span class="title">Changed in Django 1.7.1:</span> <p>If you want to include literal percent signs in a query without parameters you don’t need to double them anymore.</p> </div> <div class="versionchanged"> <span class="title">Changed in Django 1.8:</span> <p>The ability to pass parameters to the <code class="docutils literal"><span class="pre">sql</span></code> and <code class="docutils literal"><span class="pre">reverse_sql</span></code> queries was added.</p> <p>The <code class="docutils literal"><span class="pre">hints</span></code> argument was added.</p> </div> <dl class="attribute"> <dt id="django.db.migrations.operations.RunSQL.noop"> <code class="descclassname">RunSQL.</code><code class="descname">noop</code><a class="headerlink" href="#django.db.migrations.operations.RunSQL.noop" title="Permalink to this definition">¶</a></dt> <dd><div class="versionadded"> <span class="title">New in Django 1.8.</span> </div> <p>Pass the <code class="docutils literal"><span class="pre">RunSQL.noop</span></code> attribute to <code class="docutils literal"><span class="pre">sql</span></code> or <code class="docutils literal"><span class="pre">reverse_sql</span></code> when you want the operation not to do anything in the given direction. This is especially useful in making the operation reversible.</p> </dd></dl> </div> <div class="section" id="s-runpython"> <span id="runpython"></span><h3>RunPython<a class="headerlink" href="#runpython" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.RunPython"> <em class="property">class </em><code class="descname">RunPython</code>(<em>code</em>, <em>reverse_code=None</em>, <em>atomic=True</em>, <em>hints=None</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/special.html#RunPython"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.RunPython" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Runs custom Python code in a historical context. <code class="docutils literal"><span class="pre">code</span></code> (and <code class="docutils literal"><span class="pre">reverse_code</span></code> if supplied) should be callable objects that accept two arguments; the first is an instance of <code class="docutils literal"><span class="pre">django.apps.registry.Apps</span></code> containing historical models that match the operation’s place in the project history, and the second is an instance of <a class="reference internal" href="schema-editor.html#django.db.backends.base.schema.BaseDatabaseSchemaEditor" title="django.db.backends.base.schema.BaseDatabaseSchemaEditor"><code class="xref py py-class docutils literal"><span class="pre">SchemaEditor</span></code></a>.</p> <p>The <code class="docutils literal"><span class="pre">reverse_code</span></code> argument is called when unapplying migrations. This callable should undo what is done in the <code class="docutils literal"><span class="pre">code</span></code> callable so that the migration is reversible.</p> <p>The optional <code class="docutils literal"><span class="pre">hints</span></code> argument will be passed as <code class="docutils literal"><span class="pre">**hints</span></code> to the <a class="reference internal" href="../topics/db/multi-db.html#allow_migrate" title="allow_migrate"><code class="xref py py-meth docutils literal"><span class="pre">allow_migrate()</span></code></a> method of database routers to assist them in making a routing decision. See <a class="reference internal" href="../topics/db/multi-db.html#topics-db-multi-db-hints"><span class="std std-ref">Hints</span></a> for more details on database hints.</p> <div class="versionadded"> <span class="title">New in Django 1.8:</span> <p>The <code class="docutils literal"><span class="pre">hints</span></code> argument was added.</p> </div> <p>You are advised to write the code as a separate function above the <code class="docutils literal"><span class="pre">Migration</span></code> class in the migration file, and just pass it to <code class="docutils literal"><span class="pre">RunPython</span></code>. Here’s an example of using <code class="docutils literal"><span class="pre">RunPython</span></code> to create some initial objects on a <code class="docutils literal"><span class="pre">Country</span></code> model:</p> <div class="highlight-default"><div class="highlight"><pre><span></span><span class="c1"># -*- coding: utf-8 -*-</span> <span class="kn">from</span> <span class="nn">django.db</span> <span class="k">import</span> <span class="n">models</span><span class="p">,</span> <span class="n">migrations</span> <span class="k">def</span> <span class="nf">forwards_func</span><span class="p">(</span><span class="n">apps</span><span class="p">,</span> <span class="n">schema_editor</span><span class="p">):</span> <span class="c1"># We get the model from the versioned app registry;</span> <span class="c1"># if we directly import it, it'll be the wrong version</span> <span class="n">Country</span> <span class="o">=</span> <span class="n">apps</span><span class="o">.</span><span class="n">get_model</span><span class="p">(</span><span class="s2">"myapp"</span><span class="p">,</span> <span class="s2">"Country"</span><span class="p">)</span> <span class="n">db_alias</span> <span class="o">=</span> <span class="n">schema_editor</span><span class="o">.</span><span class="n">connection</span><span class="o">.</span><span class="n">alias</span> <span class="n">Country</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">using</span><span class="p">(</span><span class="n">db_alias</span><span class="p">)</span><span class="o">.</span><span class="n">bulk_create</span><span class="p">([</span> <span class="n">Country</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="s2">"USA"</span><span class="p">,</span> <span class="n">code</span><span class="o">=</span><span class="s2">"us"</span><span class="p">),</span> <span class="n">Country</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="s2">"France"</span><span class="p">,</span> <span class="n">code</span><span class="o">=</span><span class="s2">"fr"</span><span class="p">),</span> <span class="p">])</span> <span class="k">def</span> <span class="nf">reverse_func</span><span class="p">(</span><span class="n">apps</span><span class="p">,</span> <span class="n">schema_editor</span><span class="p">):</span> <span class="c1"># forwards_func() creates two Country instances,</span> <span class="c1"># so reverse_func() should delete them.</span> <span class="n">Country</span> <span class="o">=</span> <span class="n">apps</span><span class="o">.</span><span class="n">get_model</span><span class="p">(</span><span class="s2">"myapp"</span><span class="p">,</span> <span class="s2">"Country"</span><span class="p">)</span> <span class="n">db_alias</span> <span class="o">=</span> <span class="n">schema_editor</span><span class="o">.</span><span class="n">connection</span><span class="o">.</span><span class="n">alias</span> <span class="n">Country</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">using</span><span class="p">(</span><span class="n">db_alias</span><span class="p">)</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="s2">"USA"</span><span class="p">,</span> <span class="n">code</span><span class="o">=</span><span class="s2">"us"</span><span class="p">)</span><span class="o">.</span><span class="n">delete</span><span class="p">()</span> <span class="n">Country</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">using</span><span class="p">(</span><span class="n">db_alias</span><span class="p">)</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="s2">"France"</span><span class="p">,</span> <span class="n">code</span><span class="o">=</span><span class="s2">"fr"</span><span class="p">)</span><span class="o">.</span><span class="n">delete</span><span class="p">()</span> <span class="k">class</span> <span class="nc">Migration</span><span class="p">(</span><span class="n">migrations</span><span class="o">.</span><span class="n">Migration</span><span class="p">):</span> <span class="n">dependencies</span> <span class="o">=</span> <span class="p">[]</span> <span class="n">operations</span> <span class="o">=</span> <span class="p">[</span> <span class="n">migrations</span><span class="o">.</span><span class="n">RunPython</span><span class="p">(</span><span class="n">forwards_func</span><span class="p">,</span> <span class="n">reverse_func</span><span class="p">),</span> <span class="p">]</span> </pre></div> </div> <p>This is generally the operation you would use to create <a class="reference internal" href="../topics/migrations.html#data-migrations"><span class="std std-ref">data migrations</span></a>, run custom data updates and alterations, and anything else you need access to an ORM and/or Python code for.</p> <p>If you’re upgrading from South, this is basically the South pattern as an operation - one or two methods for forwards and backwards, with an ORM and schema operations available. Most of the time, you should be able to translate the <code class="docutils literal"><span class="pre">orm.Model</span></code> or <code class="docutils literal"><span class="pre">orm["appname",</span> <span class="pre">"Model"]</span></code> references from South directly into <code class="docutils literal"><span class="pre">apps.get_model("appname",</span> <span class="pre">"Model")</span></code> references here and leave most of the rest of the code unchanged for data migrations. However, <code class="docutils literal"><span class="pre">apps</span></code> will only have references to models in the current app unless migrations in other apps are added to the migration’s dependencies.</p> <p>Much like <a class="reference internal" href="#django.db.migrations.operations.RunSQL" title="django.db.migrations.operations.RunSQL"><code class="xref py py-class docutils literal"><span class="pre">RunSQL</span></code></a>, ensure that if you change schema inside here you’re either doing it outside the scope of the Django model system (e.g. triggers) or that you use <a class="reference internal" href="#django.db.migrations.operations.SeparateDatabaseAndState" title="django.db.migrations.operations.SeparateDatabaseAndState"><code class="xref py py-class docutils literal"><span class="pre">SeparateDatabaseAndState</span></code></a> to add in operations that will reflect your changes to the model state - otherwise, the versioned ORM and the autodetector will stop working correctly.</p> <p>By default, <code class="docutils literal"><span class="pre">RunPython</span></code> will run its contents inside a transaction on databases that do not support DDL transactions (for example, MySQL and Oracle). This should be safe, but may cause a crash if you attempt to use the <code class="docutils literal"><span class="pre">schema_editor</span></code> provided on these backends; in this case, pass <code class="docutils literal"><span class="pre">atomic=False</span></code> to the <code class="docutils literal"><span class="pre">RunPython</span></code> operation.</p> <p>On databases that do support DDL transactions (SQLite and PostgreSQL), <code class="docutils literal"><span class="pre">RunPython</span></code> operations do not have any transactions automatically added besides the transactions created for each migration (the <code class="docutils literal"><span class="pre">atomic</span></code> parameter has no effect on these databases). Thus, on PostgreSQL, for example, you should avoid combining schema changes and <code class="docutils literal"><span class="pre">RunPython</span></code> operations in the same migration or you may hit errors like <code class="docutils literal"><span class="pre">OperationalError:</span> <span class="pre">cannot</span> <span class="pre">ALTER</span> <span class="pre">TABLE</span> <span class="pre">"mytable"</span> <span class="pre">because</span> <span class="pre">it</span> <span class="pre">has</span> <span class="pre">pending</span> <span class="pre">trigger</span> <span class="pre">events</span></code>.</p> <p>If you have a different database and aren’t sure if it supports DDL transactions, check the <code class="docutils literal"><span class="pre">django.db.connection.features.can_rollback_ddl</span></code> attribute.</p> <div class="admonition warning"> <p class="first admonition-title">Warning</p> <p class="last"><code class="docutils literal"><span class="pre">RunPython</span></code> does not magically alter the connection of the models for you; any model methods you call will go to the default database unless you give them the current database alias (available from <code class="docutils literal"><span class="pre">schema_editor.connection.alias</span></code>, where <code class="docutils literal"><span class="pre">schema_editor</span></code> is the second argument to your function).</p> </div> <dl class="staticmethod"> <dt id="django.db.migrations.operations.RunPython.noop"> <em class="property">static </em><code class="descclassname">RunPython.</code><code class="descname">noop</code>()<a class="reference internal" href="../_modules/django/db/migrations/operations/special.html#RunPython.noop"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.RunPython.noop" title="Permalink to this definition">¶</a></dt> <dd><div class="versionadded"> <span class="title">New in Django 1.8.</span> </div> <p>Pass the <code class="docutils literal"><span class="pre">RunPython.noop</span></code> method to <code class="docutils literal"><span class="pre">code</span></code> or <code class="docutils literal"><span class="pre">reverse_code</span></code> when you want the operation not to do anything in the given direction. This is especially useful in making the operation reversible.</p> </dd></dl> </div> <div class="section" id="s-separatedatabaseandstate"> <span id="separatedatabaseandstate"></span><h3>SeparateDatabaseAndState<a class="headerlink" href="#separatedatabaseandstate" title="Permalink to this headline">¶</a></h3> <dl class="class"> <dt id="django.db.migrations.operations.SeparateDatabaseAndState"> <em class="property">class </em><code class="descname">SeparateDatabaseAndState</code>(<em>database_operations=None</em>, <em>state_operations=None</em>)<a class="reference internal" href="../_modules/django/db/migrations/operations/special.html#SeparateDatabaseAndState"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.db.migrations.operations.SeparateDatabaseAndState" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>A highly specialized operation that let you mix and match the database (schema-changing) and state (autodetector-powering) aspects of operations.</p> <p>It accepts two list of operations, and when asked to apply state will use the state list, and when asked to apply changes to the database will use the database list. Do not use this operation unless you’re very sure you know what you’re doing.</p> </div> </div> <div class="section" id="s-writing-your-own"> <span id="writing-your-own"></span><h2>Writing your own<a class="headerlink" href="#writing-your-own" title="Permalink to this headline">¶</a></h2> <p>Operations have a relatively simple API, and they’re designed so that you can easily write your own to supplement the built-in Django ones. The basic structure of an <code class="docutils literal"><span class="pre">Operation</span></code> looks like this:</p> <div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">django.db.migrations.operations.base</span> <span class="k">import</span> <span class="n">Operation</span> <span class="k">class</span> <span class="nc">MyCustomOperation</span><span class="p">(</span><span class="n">Operation</span><span class="p">):</span> <span class="c1"># If this is False, it means that this operation will be ignored by</span> <span class="c1"># sqlmigrate; if true, it will be run and the SQL collected for its output.</span> <span class="n">reduces_to_sql</span> <span class="o">=</span> <span class="kc">False</span> <span class="c1"># If this is False, Django will refuse to reverse past this operation.</span> <span class="n">reversible</span> <span class="o">=</span> <span class="kc">False</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg1</span><span class="p">,</span> <span class="n">arg2</span><span class="p">):</span> <span class="c1"># Operations are usually instantiated with arguments in migration</span> <span class="c1"># files. Store the values of them on self for later use.</span> <span class="k">pass</span> <span class="k">def</span> <span class="nf">state_forwards</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">app_label</span><span class="p">,</span> <span class="n">state</span><span class="p">):</span> <span class="c1"># The Operation should take the 'state' parameter (an instance of</span> <span class="c1"># django.db.migrations.state.ProjectState) and mutate it to match</span> <span class="c1"># any schema changes that have occurred.</span> <span class="k">pass</span> <span class="k">def</span> <span class="nf">database_forwards</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">app_label</span><span class="p">,</span> <span class="n">schema_editor</span><span class="p">,</span> <span class="n">from_state</span><span class="p">,</span> <span class="n">to_state</span><span class="p">):</span> <span class="c1"># The Operation should use schema_editor to apply any changes it</span> <span class="c1"># wants to make to the database.</span> <span class="k">pass</span> <span class="k">def</span> <span class="nf">database_backwards</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">app_label</span><span class="p">,</span> <span class="n">schema_editor</span><span class="p">,</span> <span class="n">from_state</span><span class="p">,</span> <span class="n">to_state</span><span class="p">):</span> <span class="c1"># If reversible is True, this is called when the operation is reversed.</span> <span class="k">pass</span> <span class="k">def</span> <span class="nf">describe</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="c1"># This is used to describe what the operation does in console output.</span> <span class="k">return</span> <span class="s2">"Custom Operation"</span> </pre></div> </div> <p>You can take this template and work from it, though we suggest looking at the built-in Django operations in <code class="docutils literal"><span class="pre">django.db.migrations.operations</span></code> - they’re easy to read and cover a lot of the example usage of semi-internal aspects of the migration framework like <code class="docutils literal"><span class="pre">ProjectState</span></code> and the patterns used to get historical models.</p> <p>Some things to note:</p> <ul class="simple"> <li>You don’t need to learn too much about <code class="docutils literal"><span class="pre">ProjectState</span></code> to just write simple migrations; just know that it has an <code class="docutils literal"><span class="pre">apps</span></code> property that gives access to an app registry (which you can then call <code class="docutils literal"><span class="pre">get_model</span></code> on).</li> <li><code class="docutils literal"><span class="pre">database_forwards</span></code> and <code class="docutils literal"><span class="pre">database_backwards</span></code> both get two states passed to them; these just represent the difference the <code class="docutils literal"><span class="pre">state_forwards</span></code> method would have applied, but are given to you for convenience and speed reasons.</li> <li><code class="docutils literal"><span class="pre">to_state</span></code> in the database_backwards method is the <em>older</em> state; that is, the one that will be the current state once the migration has finished reversing.</li> <li>You might see implementations of <code class="docutils literal"><span class="pre">references_model</span></code> on the built-in operations; this is part of the autodetection code and does not matter for custom operations.</li> </ul> <p>As a simple example, let’s make an operation that loads PostgreSQL extensions (which contain some of PostgreSQL’s more exciting features). It’s simple enough; there’s no model state changes, and all it does is run one command:</p> <div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">django.db.migrations.operations.base</span> <span class="k">import</span> <span class="n">Operation</span> <span class="k">class</span> <span class="nc">LoadExtension</span><span class="p">(</span><span class="n">Operation</span><span class="p">):</span> <span class="n">reversible</span> <span class="o">=</span> <span class="kc">True</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">name</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span> <span class="o">=</span> <span class="n">name</span> <span class="k">def</span> <span class="nf">state_forwards</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">app_label</span><span class="p">,</span> <span class="n">state</span><span class="p">):</span> <span class="k">pass</span> <span class="k">def</span> <span class="nf">database_forwards</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">app_label</span><span class="p">,</span> <span class="n">schema_editor</span><span class="p">,</span> <span class="n">from_state</span><span class="p">,</span> <span class="n">to_state</span><span class="p">):</span> <span class="n">schema_editor</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s2">"CREATE EXTENSION IF NOT EXISTS </span><span class="si">%s</span><span class="s2">"</span> <span class="o">%</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span><span class="p">)</span> <span class="k">def</span> <span class="nf">database_backwards</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">app_label</span><span class="p">,</span> <span class="n">schema_editor</span><span class="p">,</span> <span class="n">from_state</span><span class="p">,</span> <span class="n">to_state</span><span class="p">):</span> <span class="n">schema_editor</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s2">"DROP EXTENSION </span><span class="si">%s</span><span class="s2">"</span> <span class="o">%</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span><span class="p">)</span> <span class="k">def</span> <span class="nf">describe</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="k">return</span> <span class="s2">"Creates extension </span><span class="si">%s</span><span class="s2">"</span> <span class="o">%</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span> </pre></div> </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="#">Migration Operations</a><ul> <li><a class="reference internal" href="#schema-operations">Schema Operations</a><ul> <li><a class="reference internal" href="#createmodel">CreateModel</a></li> <li><a class="reference internal" href="#deletemodel">DeleteModel</a></li> <li><a class="reference internal" href="#renamemodel">RenameModel</a></li> <li><a class="reference internal" href="#altermodeltable">AlterModelTable</a></li> <li><a class="reference internal" href="#alteruniquetogether">AlterUniqueTogether</a></li> <li><a class="reference internal" href="#alterindextogether">AlterIndexTogether</a></li> <li><a class="reference internal" href="#alterorderwithrespectto">AlterOrderWithRespectTo</a></li> <li><a class="reference internal" href="#altermodeloptions">AlterModelOptions</a></li> <li><a class="reference internal" href="#altermodelmanagers">AlterModelManagers</a></li> <li><a class="reference internal" href="#addfield">AddField</a></li> <li><a class="reference internal" href="#removefield">RemoveField</a></li> <li><a class="reference internal" href="#alterfield">AlterField</a></li> <li><a class="reference internal" href="#renamefield">RenameField</a></li> </ul> </li> <li><a class="reference internal" href="#special-operations">Special Operations</a><ul> <li><a class="reference internal" href="#runsql">RunSQL</a></li> <li><a class="reference internal" href="#runpython">RunPython</a></li> <li><a class="reference internal" href="#separatedatabaseandstate">SeparateDatabaseAndState</a></li> </ul> </li> <li><a class="reference internal" href="#writing-your-own">Writing your own</a></li> </ul> </li> </ul> <h3>Browse</h3> <ul> <li>Prev: <a href="middleware.html">Middleware</a></li> <li>Next: 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