<!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>django.db.models.deletion — 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" 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id="_modules-django-db-models-deletion"> <h1>Source code for django.db.models.deletion</h1><div class="highlight"><pre> <span></span><span class="kn">from</span> <span class="nn">collections</span> <span class="k">import</span> <span class="n">OrderedDict</span> <span class="kn">from</span> <span class="nn">itertools</span> <span class="k">import</span> <span class="n">chain</span> <span class="kn">from</span> <span class="nn">operator</span> <span class="k">import</span> <span class="n">attrgetter</span> <span class="kn">from</span> <span class="nn">django.db</span> <span class="k">import</span> <span class="n">IntegrityError</span><span class="p">,</span> <span class="n">connections</span><span class="p">,</span> <span class="n">transaction</span> <span class="kn">from</span> <span class="nn">django.db.models</span> <span class="k">import</span> <span class="n">signals</span><span class="p">,</span> <span class="n">sql</span> <span class="kn">from</span> <span class="nn">django.utils</span> <span class="k">import</span> <span class="n">six</span> <span class="k">class</span> <span class="nc">ProtectedError</span><span class="p">(</span><span class="n">IntegrityError</span><span class="p">):</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">msg</span><span class="p">,</span> <span class="n">protected_objects</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">protected_objects</span> <span class="o">=</span> <span class="n">protected_objects</span> <span class="nb">super</span><span class="p">(</span><span class="n">ProtectedError</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">__init__</span><span class="p">(</span><span class="n">msg</span><span class="p">,</span> <span class="n">protected_objects</span><span class="p">)</span> <div class="viewcode-block" id="CASCADE"><a class="viewcode-back" href="../../../../ref/models/fields.html#django.db.CASCADE">[docs]</a><span class="k">def</span> <span class="nf">CASCADE</span><span class="p">(</span><span class="n">collector</span><span class="p">,</span> <span class="n">field</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">,</span> <span class="n">using</span><span class="p">):</span> <span class="n">collector</span><span class="o">.</span><span class="n">collect</span><span class="p">(</span><span class="n">sub_objs</span><span class="p">,</span> <span class="n">source</span><span class="o">=</span><span class="n">field</span><span class="o">.</span><span class="n">rel</span><span class="o">.</span><span class="n">to</span><span class="p">,</span> <span class="n">source_attr</span><span class="o">=</span><span class="n">field</span><span class="o">.</span><span class="n">name</span><span class="p">,</span> <span class="n">nullable</span><span class="o">=</span><span class="n">field</span><span class="o">.</span><span class="n">null</span><span class="p">)</span> <span class="k">if</span> <span class="n">field</span><span class="o">.</span><span class="n">null</span> <span class="ow">and</span> <span class="ow">not</span> <span class="n">connections</span><span class="p">[</span><span class="n">using</span><span class="p">]</span><span class="o">.</span><span class="n">features</span><span class="o">.</span><span class="n">can_defer_constraint_checks</span><span class="p">:</span> <span class="n">collector</span><span class="o">.</span><span class="n">add_field_update</span><span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="kc">None</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">)</span></div> <div class="viewcode-block" id="PROTECT"><a class="viewcode-back" href="../../../../ref/models/fields.html#django.db.PROTECT">[docs]</a><span class="k">def</span> <span class="nf">PROTECT</span><span class="p">(</span><span class="n">collector</span><span class="p">,</span> <span class="n">field</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">,</span> <span class="n">using</span><span class="p">):</span> <span class="k">raise</span> <span class="n">ProtectedError</span><span class="p">(</span><span class="s2">"Cannot delete some instances of model '</span><span class="si">%s</span><span class="s2">' because "</span> <span class="s2">"they are referenced through a protected foreign key: '</span><span class="si">%s</span><span class="s2">.</span><span class="si">%s</span><span class="s2">'"</span> <span class="o">%</span> <span class="p">(</span> <span class="n">field</span><span class="o">.</span><span class="n">rel</span><span class="o">.</span><span class="n">to</span><span class="o">.</span><span class="n">__name__</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">__class__</span><span class="o">.</span><span class="n">__name__</span><span class="p">,</span> <span class="n">field</span><span class="o">.</span><span class="n">name</span> <span class="p">),</span> <span class="n">sub_objs</span> <span class="p">)</span></div> <div class="viewcode-block" id="SET"><a class="viewcode-back" href="../../../../ref/models/fields.html#django.db.SET">[docs]</a><span class="k">def</span> <span class="nf">SET</span><span class="p">(</span><span class="n">value</span><span class="p">):</span> <span class="k">if</span> <span class="n">callable</span><span class="p">(</span><span class="n">value</span><span class="p">):</span> <span class="k">def</span> <span class="nf">set_on_delete</span><span class="p">(</span><span class="n">collector</span><span class="p">,</span> <span class="n">field</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">,</span> <span class="n">using</span><span class="p">):</span> <span class="n">collector</span><span class="o">.</span><span class="n">add_field_update</span><span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="n">value</span><span class="p">(),</span> <span class="n">sub_objs</span><span class="p">)</span> <span class="k">else</span><span class="p">:</span> <span class="k">def</span> <span class="nf">set_on_delete</span><span class="p">(</span><span class="n">collector</span><span class="p">,</span> <span class="n">field</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">,</span> <span class="n">using</span><span class="p">):</span> <span class="n">collector</span><span class="o">.</span><span class="n">add_field_update</span><span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="n">value</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">)</span> <span class="n">set_on_delete</span><span class="o">.</span><span class="n">deconstruct</span> <span class="o">=</span> <span class="k">lambda</span><span class="p">:</span> <span class="p">(</span><span class="s1">'django.db.models.SET'</span><span class="p">,</span> <span class="p">(</span><span class="n">value</span><span class="p">,),</span> <span class="p">{})</span> <span class="k">return</span> <span class="n">set_on_delete</span></div> <div class="viewcode-block" id="SET_NULL"><a class="viewcode-back" href="../../../../ref/models/fields.html#django.db.SET_NULL">[docs]</a><span class="k">def</span> <span class="nf">SET_NULL</span><span class="p">(</span><span class="n">collector</span><span class="p">,</span> <span class="n">field</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">,</span> <span class="n">using</span><span class="p">):</span> <span class="n">collector</span><span class="o">.</span><span class="n">add_field_update</span><span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="kc">None</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">)</span></div> <div class="viewcode-block" id="SET_DEFAULT"><a class="viewcode-back" href="../../../../ref/models/fields.html#django.db.SET_DEFAULT">[docs]</a><span class="k">def</span> <span class="nf">SET_DEFAULT</span><span class="p">(</span><span class="n">collector</span><span class="p">,</span> <span class="n">field</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">,</span> <span class="n">using</span><span class="p">):</span> <span class="n">collector</span><span class="o">.</span><span class="n">add_field_update</span><span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="n">field</span><span class="o">.</span><span class="n">get_default</span><span class="p">(),</span> <span class="n">sub_objs</span><span class="p">)</span></div> <div class="viewcode-block" id="DO_NOTHING"><a class="viewcode-back" href="../../../../ref/models/fields.html#django.db.DO_NOTHING">[docs]</a><span class="k">def</span> <span class="nf">DO_NOTHING</span><span class="p">(</span><span class="n">collector</span><span class="p">,</span> <span class="n">field</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">,</span> <span class="n">using</span><span class="p">):</span> <span class="k">pass</span></div> <span class="k">def</span> <span class="nf">get_candidate_relations_to_delete</span><span class="p">(</span><span class="n">opts</span><span class="p">):</span> <span class="c1"># Collect models that contain candidate relations to delete. This may include</span> <span class="c1"># relations coming from proxy models.</span> <span class="n">candidate_models</span> <span class="o">=</span> <span class="p">{</span><span class="n">opts</span><span class="p">}</span> <span class="n">candidate_models</span> <span class="o">=</span> <span class="n">candidate_models</span><span class="o">.</span><span class="n">union</span><span class="p">(</span><span class="n">opts</span><span class="o">.</span><span class="n">concrete_model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">proxied_children</span><span class="p">)</span> <span class="c1"># For each model, get all candidate fields.</span> <span class="n">candidate_model_fields</span> <span class="o">=</span> <span class="nb">set</span><span class="p">(</span><span class="n">chain</span><span class="o">.</span><span class="n">from_iterable</span><span class="p">(</span> <span class="n">opts</span><span class="o">.</span><span class="n">get_fields</span><span class="p">(</span><span class="n">include_hidden</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span> <span class="k">for</span> <span class="n">opts</span> <span class="ow">in</span> <span class="n">candidate_models</span> <span class="p">))</span> <span class="c1"># The candidate relations are the ones that come from N-1 and 1-1 relations.</span> <span class="c1"># N-N (i.e., many-to-many) relations aren't candidates for deletion.</span> <span class="k">return</span> <span class="p">(</span> <span class="n">f</span> <span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">candidate_model_fields</span> <span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">auto_created</span> <span class="ow">and</span> <span class="ow">not</span> <span class="n">f</span><span class="o">.</span><span class="n">concrete</span> <span class="ow">and</span> <span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="n">one_to_one</span> <span class="ow">or</span> <span class="n">f</span><span class="o">.</span><span class="n">one_to_many</span><span class="p">)</span> <span class="p">)</span> <span class="k">class</span> <span class="nc">Collector</span><span class="p">(</span><span class="nb">object</span><span class="p">):</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">using</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">using</span> <span class="o">=</span> <span class="n">using</span> <span class="c1"># Initially, {model: {instances}}, later values become lists.</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span> <span class="o">=</span> <span class="p">{}</span> <span class="bp">self</span><span class="o">.</span><span class="n">field_updates</span> <span class="o">=</span> <span class="p">{}</span> <span class="c1"># {model: {(field, value): {instances}}}</span> <span class="c1"># fast_deletes is a list of queryset-likes that can be deleted without</span> <span class="c1"># fetching the objects into memory.</span> <span class="bp">self</span><span class="o">.</span><span class="n">fast_deletes</span> <span class="o">=</span> <span class="p">[]</span> <span class="c1"># Tracks deletion-order dependency for databases without transactions</span> <span class="c1"># or ability to defer constraint checks. Only concrete model classes</span> <span class="c1"># should be included, as the dependencies exist only between actual</span> <span class="c1"># database tables; proxy models are represented here by their concrete</span> <span class="c1"># parent.</span> <span class="bp">self</span><span class="o">.</span><span class="n">dependencies</span> <span class="o">=</span> <span class="p">{}</span> <span class="c1"># {model: {models}}</span> <span class="k">def</span> <span class="nf">add</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">objs</span><span class="p">,</span> <span class="n">source</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">nullable</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="n">reverse_dependency</span><span class="o">=</span><span class="kc">False</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Adds 'objs' to the collection of objects to be deleted. If the call is</span> <span class="sd"> the result of a cascade, 'source' should be the model that caused it,</span> <span class="sd"> and 'nullable' should be set to True if the relation can be null.</span> <span class="sd"> Returns a list of all objects that were not already collected.</span> <span class="sd"> """</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">objs</span><span class="p">:</span> <span class="k">return</span> <span class="p">[]</span> <span class="n">new_objs</span> <span class="o">=</span> <span class="p">[]</span> <span class="n">model</span> <span class="o">=</span> <span class="n">objs</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">__class__</span> <span class="n">instances</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="o">.</span><span class="n">setdefault</span><span class="p">(</span><span class="n">model</span><span class="p">,</span> <span class="nb">set</span><span class="p">())</span> <span class="k">for</span> <span class="n">obj</span> <span class="ow">in</span> <span class="n">objs</span><span class="p">:</span> <span class="k">if</span> <span class="n">obj</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">instances</span><span class="p">:</span> <span class="n">new_objs</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">obj</span><span class="p">)</span> <span class="n">instances</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">new_objs</span><span class="p">)</span> <span class="c1"># Nullable relationships can be ignored -- they are nulled out before</span> <span class="c1"># deleting, and therefore do not affect the order in which objects have</span> <span class="c1"># to be deleted.</span> <span class="k">if</span> <span class="n">source</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span> <span class="ow">and</span> <span class="ow">not</span> <span class="n">nullable</span><span class="p">:</span> <span class="k">if</span> <span class="n">reverse_dependency</span><span class="p">:</span> <span class="n">source</span><span class="p">,</span> <span class="n">model</span> <span class="o">=</span> <span class="n">model</span><span class="p">,</span> <span class="n">source</span> <span class="bp">self</span><span class="o">.</span><span class="n">dependencies</span><span class="o">.</span><span class="n">setdefault</span><span class="p">(</span> <span class="n">source</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">concrete_model</span><span class="p">,</span> <span class="nb">set</span><span class="p">())</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">concrete_model</span><span class="p">)</span> <span class="k">return</span> <span class="n">new_objs</span> <span class="k">def</span> <span class="nf">add_field_update</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">field</span><span class="p">,</span> <span class="n">value</span><span class="p">,</span> <span class="n">objs</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Schedules a field update. 'objs' must be a homogeneous iterable</span> <span class="sd"> collection of model instances (e.g. a QuerySet).</span> <span class="sd"> """</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">objs</span><span class="p">:</span> <span class="k">return</span> <span class="n">model</span> <span class="o">=</span> <span class="n">objs</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">__class__</span> <span class="bp">self</span><span class="o">.</span><span class="n">field_updates</span><span class="o">.</span><span class="n">setdefault</span><span class="p">(</span> <span class="n">model</span><span class="p">,</span> <span class="p">{})</span><span class="o">.</span><span class="n">setdefault</span><span class="p">(</span> <span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="n">value</span><span class="p">),</span> <span class="nb">set</span><span class="p">())</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">objs</span><span class="p">)</span> <span class="k">def</span> <span class="nf">can_fast_delete</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">objs</span><span class="p">,</span> <span class="n">from_field</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Determines if the objects in the given queryset-like can be</span> <span class="sd"> fast-deleted. This can be done if there are no cascades, no</span> <span class="sd"> parents and no signal listeners for the object class.</span> <span class="sd"> The 'from_field' tells where we are coming from - we need this to</span> <span class="sd"> determine if the objects are in fact to be deleted. Allows also</span> <span class="sd"> skipping parent -> child -> parent chain preventing fast delete of</span> <span class="sd"> the child.</span> <span class="sd"> """</span> <span class="k">if</span> <span class="n">from_field</span> <span class="ow">and</span> <span class="n">from_field</span><span class="o">.</span><span class="n">rel</span><span class="o">.</span><span class="n">on_delete</span> <span class="ow">is</span> <span class="ow">not</span> <span class="n">CASCADE</span><span class="p">:</span> <span class="k">return</span> <span class="kc">False</span> <span class="k">if</span> <span class="ow">not</span> <span class="p">(</span><span class="nb">hasattr</span><span class="p">(</span><span class="n">objs</span><span class="p">,</span> <span class="s1">'model'</span><span class="p">)</span> <span class="ow">and</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">objs</span><span class="p">,</span> <span class="s1">'_raw_delete'</span><span class="p">)):</span> <span class="k">return</span> <span class="kc">False</span> <span class="n">model</span> <span class="o">=</span> <span class="n">objs</span><span class="o">.</span><span class="n">model</span> <span class="k">if</span> <span class="p">(</span><span class="n">signals</span><span class="o">.</span><span class="n">pre_delete</span><span class="o">.</span><span class="n">has_listeners</span><span class="p">(</span><span class="n">model</span><span class="p">)</span> <span class="ow">or</span> <span class="n">signals</span><span class="o">.</span><span class="n">post_delete</span><span class="o">.</span><span class="n">has_listeners</span><span class="p">(</span><span class="n">model</span><span class="p">)</span> <span class="ow">or</span> <span class="n">signals</span><span class="o">.</span><span class="n">m2m_changed</span><span class="o">.</span><span class="n">has_listeners</span><span class="p">(</span><span class="n">model</span><span class="p">)):</span> <span class="k">return</span> <span class="kc">False</span> <span class="c1"># The use of from_field comes from the need to avoid cascade back to</span> <span class="c1"># parent when parent delete is cascading to child.</span> <span class="n">opts</span> <span class="o">=</span> <span class="n">model</span><span class="o">.</span><span class="n">_meta</span> <span class="k">if</span> <span class="nb">any</span><span class="p">(</span><span class="n">link</span> <span class="o">!=</span> <span class="n">from_field</span> <span class="k">for</span> <span class="n">link</span> <span class="ow">in</span> <span class="n">opts</span><span class="o">.</span><span class="n">concrete_model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">parents</span><span class="o">.</span><span class="n">values</span><span class="p">()):</span> <span class="k">return</span> <span class="kc">False</span> <span class="c1"># Foreign keys pointing to this model, both from m2m and other</span> <span class="c1"># models.</span> <span class="k">for</span> <span class="n">related</span> <span class="ow">in</span> <span class="n">get_candidate_relations_to_delete</span><span class="p">(</span><span class="n">opts</span><span class="p">):</span> <span class="k">if</span> <span class="n">related</span><span class="o">.</span><span class="n">field</span><span class="o">.</span><span class="n">rel</span><span class="o">.</span><span class="n">on_delete</span> <span class="ow">is</span> <span class="ow">not</span> <span class="n">DO_NOTHING</span><span class="p">:</span> <span class="k">return</span> <span class="kc">False</span> <span class="k">for</span> <span class="n">field</span> <span class="ow">in</span> <span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">virtual_fields</span><span class="p">:</span> <span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="s1">'bulk_related_objects'</span><span class="p">):</span> <span class="c1"># It's something like generic foreign key.</span> <span class="k">return</span> <span class="kc">False</span> <span class="k">return</span> <span class="kc">True</span> <span class="k">def</span> <span class="nf">get_del_batches</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">objs</span><span class="p">,</span> <span class="n">field</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Returns the objs in suitably sized batches for the used connection.</span> <span class="sd"> """</span> <span class="n">conn_batch_size</span> <span class="o">=</span> <span class="nb">max</span><span class="p">(</span> <span class="n">connections</span><span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">using</span><span class="p">]</span><span class="o">.</span><span class="n">ops</span><span class="o">.</span><span class="n">bulk_batch_size</span><span class="p">([</span><span class="n">field</span><span class="o">.</span><span class="n">name</span><span class="p">],</span> <span class="n">objs</span><span class="p">),</span> <span class="mi">1</span><span class="p">)</span> <span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="n">objs</span><span class="p">)</span> <span class="o">></span> <span class="n">conn_batch_size</span><span class="p">:</span> <span class="k">return</span> <span class="p">[</span><span class="n">objs</span><span class="p">[</span><span class="n">i</span><span class="p">:</span><span class="n">i</span> <span class="o">+</span> <span class="n">conn_batch_size</span><span class="p">]</span> <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="n">objs</span><span class="p">),</span> <span class="n">conn_batch_size</span><span class="p">)]</span> <span class="k">else</span><span class="p">:</span> <span class="k">return</span> <span class="p">[</span><span class="n">objs</span><span class="p">]</span> <span class="k">def</span> <span class="nf">collect</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">objs</span><span class="p">,</span> <span class="n">source</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">nullable</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="n">collect_related</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span> <span class="n">source_attr</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">reverse_dependency</span><span class="o">=</span><span class="kc">False</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Adds 'objs' to the collection of objects to be deleted as well as all</span> <span class="sd"> parent instances. 'objs' must be a homogeneous iterable collection of</span> <span class="sd"> model instances (e.g. a QuerySet). If 'collect_related' is True,</span> <span class="sd"> related objects will be handled by their respective on_delete handler.</span> <span class="sd"> If the call is the result of a cascade, 'source' should be the model</span> <span class="sd"> that caused it and 'nullable' should be set to True, if the relation</span> <span class="sd"> can be null.</span> <span class="sd"> If 'reverse_dependency' is True, 'source' will be deleted before the</span> <span class="sd"> current model, rather than after. (Needed for cascading to parent</span> <span class="sd"> models, the one case in which the cascade follows the forwards</span> <span class="sd"> direction of an FK rather than the reverse direction.)</span> <span class="sd"> """</span> <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">can_fast_delete</span><span class="p">(</span><span class="n">objs</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">fast_deletes</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">objs</span><span class="p">)</span> <span class="k">return</span> <span class="n">new_objs</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="n">objs</span><span class="p">,</span> <span class="n">source</span><span class="p">,</span> <span class="n">nullable</span><span class="p">,</span> <span class="n">reverse_dependency</span><span class="o">=</span><span class="n">reverse_dependency</span><span class="p">)</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">new_objs</span><span class="p">:</span> <span class="k">return</span> <span class="n">model</span> <span class="o">=</span> <span class="n">new_objs</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">__class__</span> <span class="c1"># Recursively collect concrete model's parent models, but not their</span> <span class="c1"># related objects. These will be found by meta.get_fields()</span> <span class="n">concrete_model</span> <span class="o">=</span> <span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">concrete_model</span> <span class="k">for</span> <span class="n">ptr</span> <span class="ow">in</span> <span class="n">six</span><span class="o">.</span><span class="n">itervalues</span><span class="p">(</span><span class="n">concrete_model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">parents</span><span class="p">):</span> <span class="k">if</span> <span class="n">ptr</span><span class="p">:</span> <span class="c1"># FIXME: This seems to be buggy and execute a query for each</span> <span class="c1"># parent object fetch. We have the parent data in the obj,</span> <span class="c1"># but we don't have a nice way to turn that data into parent</span> <span class="c1"># object instance.</span> <span class="n">parent_objs</span> <span class="o">=</span> <span class="p">[</span><span class="nb">getattr</span><span class="p">(</span><span class="n">obj</span><span class="p">,</span> <span class="n">ptr</span><span class="o">.</span><span class="n">name</span><span class="p">)</span> <span class="k">for</span> <span class="n">obj</span> <span class="ow">in</span> <span class="n">new_objs</span><span class="p">]</span> <span class="bp">self</span><span class="o">.</span><span class="n">collect</span><span class="p">(</span><span class="n">parent_objs</span><span class="p">,</span> <span class="n">source</span><span class="o">=</span><span class="n">model</span><span class="p">,</span> <span class="n">source_attr</span><span class="o">=</span><span class="n">ptr</span><span class="o">.</span><span class="n">rel</span><span class="o">.</span><span class="n">related_name</span><span class="p">,</span> <span class="n">collect_related</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="n">reverse_dependency</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span> <span class="k">if</span> <span class="n">collect_related</span><span class="p">:</span> <span class="k">for</span> <span class="n">related</span> <span class="ow">in</span> <span class="n">get_candidate_relations_to_delete</span><span class="p">(</span><span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="p">):</span> <span class="n">field</span> <span class="o">=</span> <span class="n">related</span><span class="o">.</span><span class="n">field</span> <span class="k">if</span> <span class="n">field</span><span class="o">.</span><span class="n">rel</span><span class="o">.</span><span class="n">on_delete</span> <span class="o">==</span> <span class="n">DO_NOTHING</span><span class="p">:</span> <span class="k">continue</span> <span class="n">batches</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_del_batches</span><span class="p">(</span><span class="n">new_objs</span><span class="p">,</span> <span class="n">field</span><span class="p">)</span> <span class="k">for</span> <span class="n">batch</span> <span class="ow">in</span> <span class="n">batches</span><span class="p">:</span> <span class="n">sub_objs</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">related_objects</span><span class="p">(</span><span class="n">related</span><span class="p">,</span> <span class="n">batch</span><span class="p">)</span> <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">can_fast_delete</span><span class="p">(</span><span class="n">sub_objs</span><span class="p">,</span> <span class="n">from_field</span><span class="o">=</span><span class="n">field</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">fast_deletes</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">sub_objs</span><span class="p">)</span> <span class="k">elif</span> <span class="n">sub_objs</span><span class="p">:</span> <span class="n">field</span><span class="o">.</span><span class="n">rel</span><span class="o">.</span><span class="n">on_delete</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">field</span><span class="p">,</span> <span class="n">sub_objs</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">using</span><span class="p">)</span> <span class="k">for</span> <span class="n">field</span> <span class="ow">in</span> <span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">virtual_fields</span><span class="p">:</span> <span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="s1">'bulk_related_objects'</span><span class="p">):</span> <span class="c1"># Its something like generic foreign key.</span> <span class="n">sub_objs</span> <span class="o">=</span> <span class="n">field</span><span class="o">.</span><span class="n">bulk_related_objects</span><span class="p">(</span><span class="n">new_objs</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">using</span><span class="p">)</span> <span class="bp">self</span><span class="o">.</span><span class="n">collect</span><span class="p">(</span><span class="n">sub_objs</span><span class="p">,</span> <span class="n">source</span><span class="o">=</span><span class="n">model</span><span class="p">,</span> <span class="n">source_attr</span><span class="o">=</span><span class="n">field</span><span class="o">.</span><span class="n">rel</span><span class="o">.</span><span class="n">related_name</span><span class="p">,</span> <span class="n">nullable</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span> <span class="k">def</span> <span class="nf">related_objects</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">related</span><span class="p">,</span> <span class="n">objs</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Gets a QuerySet of objects related to ``objs`` via the relation ``related``.</span> <span class="sd"> """</span> <span class="k">return</span> <span class="n">related</span><span class="o">.</span><span class="n">related_model</span><span class="o">.</span><span class="n">_base_manager</span><span class="o">.</span><span class="n">using</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">using</span><span class="p">)</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span> <span class="o">**</span><span class="p">{</span><span class="s2">"</span><span class="si">%s</span><span class="s2">__in"</span> <span class="o">%</span> <span class="n">related</span><span class="o">.</span><span class="n">field</span><span class="o">.</span><span class="n">name</span><span class="p">:</span> <span class="n">objs</span><span class="p">}</span> <span class="p">)</span> <span class="k">def</span> <span class="nf">instances_with_model</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="k">for</span> <span class="n">model</span><span class="p">,</span> <span class="n">instances</span> <span class="ow">in</span> <span class="n">six</span><span class="o">.</span><span class="n">iteritems</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">):</span> <span class="k">for</span> <span class="n">obj</span> <span class="ow">in</span> <span class="n">instances</span><span class="p">:</span> <span class="k">yield</span> <span class="n">model</span><span class="p">,</span> <span class="n">obj</span> <span class="k">def</span> <span class="nf">sort</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="n">sorted_models</span> <span class="o">=</span> <span class="p">[]</span> <span class="n">concrete_models</span> <span class="o">=</span> <span class="nb">set</span><span class="p">()</span> <span class="n">models</span> <span class="o">=</span> <span class="nb">list</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">)</span> <span class="k">while</span> <span class="nb">len</span><span class="p">(</span><span class="n">sorted_models</span><span class="p">)</span> <span class="o"><</span> <span class="nb">len</span><span class="p">(</span><span class="n">models</span><span class="p">):</span> <span class="n">found</span> <span class="o">=</span> <span class="kc">False</span> <span class="k">for</span> <span class="n">model</span> <span class="ow">in</span> <span class="n">models</span><span class="p">:</span> <span class="k">if</span> <span class="n">model</span> <span class="ow">in</span> <span class="n">sorted_models</span><span class="p">:</span> <span class="k">continue</span> <span class="n">dependencies</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">dependencies</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">concrete_model</span><span class="p">)</span> <span class="k">if</span> <span class="ow">not</span> <span class="p">(</span><span class="n">dependencies</span> <span class="ow">and</span> <span class="n">dependencies</span><span class="o">.</span><span class="n">difference</span><span class="p">(</span><span class="n">concrete_models</span><span class="p">)):</span> <span class="n">sorted_models</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">model</span><span class="p">)</span> <span class="n">concrete_models</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">concrete_model</span><span class="p">)</span> <span class="n">found</span> <span class="o">=</span> <span class="kc">True</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">found</span><span class="p">:</span> <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span> <span class="o">=</span> <span class="n">OrderedDict</span><span class="p">((</span><span class="n">model</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">[</span><span class="n">model</span><span class="p">])</span> <span class="k">for</span> <span class="n">model</span> <span class="ow">in</span> <span class="n">sorted_models</span><span class="p">)</span> <span class="k">def</span> <span class="nf">delete</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="c1"># sort instance collections</span> <span class="k">for</span> <span class="n">model</span><span class="p">,</span> <span class="n">instances</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="o">.</span><span class="n">items</span><span class="p">():</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">[</span><span class="n">model</span><span class="p">]</span> <span class="o">=</span> <span class="nb">sorted</span><span class="p">(</span><span class="n">instances</span><span class="p">,</span> <span class="n">key</span><span class="o">=</span><span class="n">attrgetter</span><span class="p">(</span><span class="s2">"pk"</span><span class="p">))</span> <span class="c1"># if possible, bring the models in an order suitable for databases that</span> <span class="c1"># don't support transactions or cannot defer constraint checks until the</span> <span class="c1"># end of a transaction.</span> <span class="bp">self</span><span class="o">.</span><span class="n">sort</span><span class="p">()</span> <span class="k">with</span> <span class="n">transaction</span><span class="o">.</span><span class="n">atomic</span><span class="p">(</span><span class="n">using</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">using</span><span class="p">,</span> <span class="n">savepoint</span><span class="o">=</span><span class="kc">False</span><span class="p">):</span> <span class="c1"># send pre_delete signals</span> <span class="k">for</span> <span class="n">model</span><span class="p">,</span> <span class="n">obj</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">instances_with_model</span><span class="p">():</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">auto_created</span><span class="p">:</span> <span class="n">signals</span><span class="o">.</span><span class="n">pre_delete</span><span class="o">.</span><span class="n">send</span><span class="p">(</span> <span class="n">sender</span><span class="o">=</span><span class="n">model</span><span class="p">,</span> <span class="n">instance</span><span class="o">=</span><span class="n">obj</span><span class="p">,</span> <span class="n">using</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">using</span> <span class="p">)</span> <span class="c1"># fast deletes</span> <span class="k">for</span> <span class="n">qs</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">fast_deletes</span><span class="p">:</span> <span class="n">qs</span><span class="o">.</span><span class="n">_raw_delete</span><span class="p">(</span><span class="n">using</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">using</span><span class="p">)</span> <span class="c1"># update fields</span> <span class="k">for</span> <span class="n">model</span><span class="p">,</span> <span class="n">instances_for_fieldvalues</span> <span class="ow">in</span> <span class="n">six</span><span class="o">.</span><span class="n">iteritems</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">field_updates</span><span class="p">):</span> <span class="n">query</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">UpdateQuery</span><span class="p">(</span><span class="n">model</span><span class="p">)</span> <span class="k">for</span> <span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="n">value</span><span class="p">),</span> <span class="n">instances</span> <span class="ow">in</span> <span class="n">six</span><span class="o">.</span><span class="n">iteritems</span><span class="p">(</span><span class="n">instances_for_fieldvalues</span><span class="p">):</span> <span class="n">query</span><span class="o">.</span><span class="n">update_batch</span><span class="p">([</span><span class="n">obj</span><span class="o">.</span><span class="n">pk</span> <span class="k">for</span> <span class="n">obj</span> <span class="ow">in</span> <span class="n">instances</span><span class="p">],</span> <span class="p">{</span><span class="n">field</span><span class="o">.</span><span class="n">name</span><span class="p">:</span> <span class="n">value</span><span class="p">},</span> <span class="bp">self</span><span class="o">.</span><span class="n">using</span><span class="p">)</span> <span class="c1"># reverse instance collections</span> <span class="k">for</span> <span class="n">instances</span> <span class="ow">in</span> <span class="n">six</span><span class="o">.</span><span class="n">itervalues</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">):</span> <span class="n">instances</span><span class="o">.</span><span class="n">reverse</span><span class="p">()</span> <span class="c1"># delete instances</span> <span class="k">for</span> <span class="n">model</span><span class="p">,</span> <span class="n">instances</span> <span class="ow">in</span> <span class="n">six</span><span class="o">.</span><span class="n">iteritems</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">):</span> <span class="n">query</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">DeleteQuery</span><span class="p">(</span><span class="n">model</span><span class="p">)</span> <span class="n">pk_list</span> <span class="o">=</span> <span class="p">[</span><span class="n">obj</span><span class="o">.</span><span class="n">pk</span> <span class="k">for</span> <span class="n">obj</span> <span class="ow">in</span> <span class="n">instances</span><span class="p">]</span> <span class="n">query</span><span class="o">.</span><span class="n">delete_batch</span><span class="p">(</span><span class="n">pk_list</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">using</span><span class="p">)</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">auto_created</span><span class="p">:</span> <span class="k">for</span> <span class="n">obj</span> <span class="ow">in</span> <span class="n">instances</span><span class="p">:</span> <span class="n">signals</span><span class="o">.</span><span class="n">post_delete</span><span class="o">.</span><span class="n">send</span><span class="p">(</span> <span class="n">sender</span><span class="o">=</span><span class="n">model</span><span class="p">,</span> <span class="n">instance</span><span class="o">=</span><span class="n">obj</span><span class="p">,</span> <span class="n">using</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">using</span> <span class="p">)</span> <span class="c1"># update collected instances</span> <span class="k">for</span> <span class="n">model</span><span class="p">,</span> <span class="n">instances_for_fieldvalues</span> <span class="ow">in</span> <span class="n">six</span><span class="o">.</span><span class="n">iteritems</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">field_updates</span><span class="p">):</span> <span class="k">for</span> <span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="n">value</span><span class="p">),</span> <span class="n">instances</span> <span class="ow">in</span> <span class="n">six</span><span class="o">.</span><span class="n">iteritems</span><span class="p">(</span><span class="n">instances_for_fieldvalues</span><span class="p">):</span> <span class="k">for</span> <span class="n">obj</span> <span class="ow">in</span> <span class="n">instances</span><span class="p">:</span> <span class="nb">setattr</span><span class="p">(</span><span class="n">obj</span><span class="p">,</span> <span class="n">field</span><span class="o">.</span><span class="n">attname</span><span class="p">,</span> <span class="n">value</span><span class="p">)</span> <span class="k">for</span> <span class="n">model</span><span class="p">,</span> <span class="n">instances</span> <span class="ow">in</span> <span class="n">six</span><span class="o">.</span><span class="n">iteritems</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">):</span> <span class="k">for</span> <span class="n">instance</span> <span class="ow">in</span> <span class="n">instances</span><span class="p">:</span> <span class="nb">setattr</span><span class="p">(</span><span class="n">instance</span><span class="p">,</span> <span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">pk</span><span class="o">.</span><span class="n">attname</span><span class="p">,</span> <span class="kc">None</span><span class="p">)</span> </pre></div> </div> </div> </div> <div class="yui-b" id="sidebar"> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h3>Browse</h3> <ul> </ul> <h3>You are here:</h3> <ul> <li> <a href="../../../../index.html">Django 1.8.19 documentation</a> <ul><li><a href="../../../index.html">Module code</a> <ul><li><a href="../../../django.html">django</a> <ul><li>django.db.models.deletion</li></ul> </li></ul></li></ul> </li> </ul> <div id="searchbox" style="display: none" role="search"> <h3>Quick search</h3> <form class="search" action="../../../../search.html" method="get"> <div><input type="text" name="q" /></div> <div><input type="submit" value="Go" /></div> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> 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