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<h1>Source code for django.db.models.manager</h1><div class="highlight"><pre>
<span></span><span class="kn">import</span> <span class="nn">copy</span>
<span class="kn">import</span> <span class="nn">inspect</span>
<span class="kn">from</span> <span class="nn">importlib</span> <span class="k">import</span> <span class="n">import_module</span>
<span class="kn">from</span> <span class="nn">django.db</span> <span class="k">import</span> <span class="n">router</span>
<span class="kn">from</span> <span class="nn">django.db.models.query</span> <span class="k">import</span> <span class="n">QuerySet</span>
<span class="kn">from</span> <span class="nn">django.utils</span> <span class="k">import</span> <span class="n">six</span>
<span class="kn">from</span> <span class="nn">django.utils.encoding</span> <span class="k">import</span> <span class="n">python_2_unicode_compatible</span>
<span class="k">def</span> <span class="nf">ensure_default_manager</span><span class="p">(</span><span class="n">cls</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Ensures that a Model subclass contains a default manager and sets the</span>
<span class="sd"> _default_manager attribute on the class. Also sets up the _base_manager</span>
<span class="sd"> points to a plain Manager instance (which could be the same as</span>
<span class="sd"> _default_manager if it's not a subclass of Manager).</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cls</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">abstract</span><span class="p">:</span>
<span class="nb">setattr</span><span class="p">(</span><span class="n">cls</span><span class="p">,</span> <span class="s1">'objects'</span><span class="p">,</span> <span class="n">AbstractManagerDescriptor</span><span class="p">(</span><span class="n">cls</span><span class="p">))</span>
<span class="k">return</span>
<span class="k">elif</span> <span class="n">cls</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">swapped</span><span class="p">:</span>
<span class="nb">setattr</span><span class="p">(</span><span class="n">cls</span><span class="p">,</span> <span class="s1">'objects'</span><span class="p">,</span> <span class="n">SwappedManagerDescriptor</span><span class="p">(</span><span class="n">cls</span><span class="p">))</span>
<span class="k">return</span>
<span class="k">if</span> <span class="ow">not</span> <span class="nb">getattr</span><span class="p">(</span><span class="n">cls</span><span class="p">,</span> <span class="s1">'_default_manager'</span><span class="p">,</span> <span class="kc">None</span><span class="p">):</span>
<span class="k">if</span> <span class="nb">any</span><span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="n">name</span> <span class="o">==</span> <span class="s1">'objects'</span> <span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">cls</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">fields</span><span class="p">):</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span>
<span class="s2">"Model </span><span class="si">%s</span><span class="s2"> must specify a custom Manager, because it has a "</span>
<span class="s2">"field named 'objects'"</span> <span class="o">%</span> <span class="n">cls</span><span class="o">.</span><span class="n">__name__</span>
<span class="p">)</span>
<span class="c1"># Create the default manager, if needed.</span>
<span class="n">cls</span><span class="o">.</span><span class="n">add_to_class</span><span class="p">(</span><span class="s1">'objects'</span><span class="p">,</span> <span class="n">Manager</span><span class="p">())</span>
<span class="n">cls</span><span class="o">.</span><span class="n">_base_manager</span> <span class="o">=</span> <span class="n">cls</span><span class="o">.</span><span class="n">objects</span>
<span class="k">elif</span> <span class="ow">not</span> <span class="nb">getattr</span><span class="p">(</span><span class="n">cls</span><span class="p">,</span> <span class="s1">'_base_manager'</span><span class="p">,</span> <span class="kc">None</span><span class="p">):</span>
<span class="n">default_mgr</span> <span class="o">=</span> <span class="n">cls</span><span class="o">.</span><span class="n">_default_manager</span><span class="o">.</span><span class="n">__class__</span>
<span class="k">if</span> <span class="p">(</span><span class="n">default_mgr</span> <span class="ow">is</span> <span class="n">Manager</span> <span class="ow">or</span>
<span class="nb">getattr</span><span class="p">(</span><span class="n">default_mgr</span><span class="p">,</span> <span class="s2">"use_for_related_fields"</span><span class="p">,</span> <span class="kc">False</span><span class="p">)):</span>
<span class="n">cls</span><span class="o">.</span><span class="n">_base_manager</span> <span class="o">=</span> <span class="n">cls</span><span class="o">.</span><span class="n">_default_manager</span>
<span class="k">else</span><span class="p">:</span>
<span class="c1"># Default manager isn't a plain Manager class, or a suitable</span>
<span class="c1"># replacement, so we walk up the base class hierarchy until we hit</span>
<span class="c1"># something appropriate.</span>
<span class="k">for</span> <span class="n">base_class</span> <span class="ow">in</span> <span class="n">default_mgr</span><span class="o">.</span><span class="n">mro</span><span class="p">()[</span><span class="mi">1</span><span class="p">:]:</span>
<span class="k">if</span> <span class="p">(</span><span class="n">base_class</span> <span class="ow">is</span> <span class="n">Manager</span> <span class="ow">or</span>
<span class="nb">getattr</span><span class="p">(</span><span class="n">base_class</span><span class="p">,</span> <span class="s2">"use_for_related_fields"</span><span class="p">,</span> <span class="kc">False</span><span class="p">)):</span>
<span class="n">cls</span><span class="o">.</span><span class="n">add_to_class</span><span class="p">(</span><span class="s1">'_base_manager'</span><span class="p">,</span> <span class="n">base_class</span><span class="p">())</span>
<span class="k">return</span>
<span class="k">raise</span> <span class="ne">AssertionError</span><span class="p">(</span>
<span class="s2">"Should never get here. Please report a bug, including your "</span>
<span class="s2">"model and model manager setup."</span>
<span class="p">)</span>
<span class="nd">@python_2_unicode_compatible</span>
<span class="k">class</span> <span class="nc">BaseManager</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="c1"># Tracks each time a Manager instance is created. Used to retain order.</span>
<span class="n">creation_counter</span> <span class="o">=</span> <span class="mi">0</span>
<span class="c1">#: If set to True the manager will be serialized into migrations and will</span>
<span class="c1">#: thus be available in e.g. RunPython operations</span>
<span class="n">use_in_migrations</span> <span class="o">=</span> <span class="kc">False</span>
<span class="k">def</span> <span class="nf">__new__</span><span class="p">(</span><span class="n">cls</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="c1"># We capture the arguments to make returning them trivial</span>
<span class="n">obj</span> <span class="o">=</span> <span class="nb">super</span><span class="p">(</span><span class="n">BaseManager</span><span class="p">,</span> <span class="n">cls</span><span class="p">)</span><span class="o">.</span><span class="n">__new__</span><span class="p">(</span><span class="n">cls</span><span class="p">)</span>
<span class="n">obj</span><span class="o">.</span><span class="n">_constructor_args</span> <span class="o">=</span> <span class="p">(</span><span class="n">args</span><span class="p">,</span> <span class="n">kwargs</span><span class="p">)</span>
<span class="k">return</span> <span class="n">obj</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="nb">super</span><span class="p">(</span><span class="n">BaseManager</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="bp">self</span><span class="o">.</span><span class="n">_set_creation_counter</span><span class="p">()</span>
<span class="bp">self</span><span class="o">.</span><span class="n">model</span> <span class="o">=</span> <span class="kc">None</span>
<span class="bp">self</span><span class="o">.</span><span class="n">name</span> <span class="o">=</span> <span class="kc">None</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_inherited</span> <span class="o">=</span> <span class="kc">False</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_db</span> <span class="o">=</span> <span class="kc">None</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_hints</span> <span class="o">=</span> <span class="p">{}</span>
<span class="k">def</span> <span class="nf">__str__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">""" Return "app_label.model_label.manager_name". """</span>
<span class="n">model</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">model</span>
<span class="n">app</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">app_label</span>
<span class="k">return</span> <span class="s1">'</span><span class="si">%s</span><span class="s1">.</span><span class="si">%s</span><span class="s1">.</span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span><span class="n">app</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">object_name</span><span class="p">,</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">deconstruct</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Returns a 5-tuple of the form (as_manager (True), manager_class,</span>
<span class="sd"> queryset_class, args, kwargs).</span>
<span class="sd"> Raises a ValueError if the manager is dynamically generated.</span>
<span class="sd"> """</span>
<span class="n">qs_class</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_queryset_class</span>
<span class="k">if</span> <span class="nb">getattr</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="s1">'_built_with_as_manager'</span><span class="p">,</span> <span class="kc">False</span><span class="p">):</span>
<span class="c1"># using MyQuerySet.as_manager()</span>
<span class="k">return</span> <span class="p">(</span>
<span class="kc">True</span><span class="p">,</span> <span class="c1"># as_manager</span>
<span class="kc">None</span><span class="p">,</span> <span class="c1"># manager_class</span>
<span class="s1">'</span><span class="si">%s</span><span class="s1">.</span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span><span class="n">qs_class</span><span class="o">.</span><span class="n">__module__</span><span class="p">,</span> <span class="n">qs_class</span><span class="o">.</span><span class="n">__name__</span><span class="p">),</span> <span class="c1"># qs_class</span>
<span class="kc">None</span><span class="p">,</span> <span class="c1"># args</span>
<span class="kc">None</span><span class="p">,</span> <span class="c1"># kwargs</span>
<span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">module_name</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">__module__</span>
<span class="n">name</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">__class__</span><span class="o">.</span><span class="n">__name__</span>
<span class="c1"># Make sure it's actually there and not an inner class</span>
<span class="n">module</span> <span class="o">=</span> <span class="n">import_module</span><span class="p">(</span><span class="n">module_name</span><span class="p">)</span>
<span class="k">if</span> <span class="ow">not</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">module</span><span class="p">,</span> <span class="n">name</span><span class="p">):</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span>
<span class="s2">"Could not find manager </span><span class="si">%s</span><span class="s2"> in </span><span class="si">%s</span><span class="s2">.</span><span class="se">\n</span><span class="s2">"</span>
<span class="s2">"Please note that you need to inherit from managers you "</span>
<span class="s2">"dynamically generated with 'from_queryset()'."</span>
<span class="o">%</span> <span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">module_name</span><span class="p">)</span>
<span class="p">)</span>
<span class="k">return</span> <span class="p">(</span>
<span class="kc">False</span><span class="p">,</span> <span class="c1"># as_manager</span>
<span class="s1">'</span><span class="si">%s</span><span class="s1">.</span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span><span class="n">module_name</span><span class="p">,</span> <span class="n">name</span><span class="p">),</span> <span class="c1"># manager_class</span>
<span class="kc">None</span><span class="p">,</span> <span class="c1"># qs_class</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_constructor_args</span><span class="p">[</span><span class="mi">0</span><span class="p">],</span> <span class="c1"># args</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_constructor_args</span><span class="p">[</span><span class="mi">1</span><span class="p">],</span> <span class="c1"># kwargs</span>
<span class="p">)</span>
<span class="k">def</span> <span class="nf">check</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="k">return</span> <span class="p">[]</span>
<span class="nd">@classmethod</span>
<span class="k">def</span> <span class="nf">_get_queryset_methods</span><span class="p">(</span><span class="n">cls</span><span class="p">,</span> <span class="n">queryset_class</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">create_method</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">method</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">manager_method</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="k">return</span> <span class="nb">getattr</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">get_queryset</span><span class="p">(),</span> <span class="n">name</span><span class="p">)(</span><span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">)</span>
<span class="n">manager_method</span><span class="o">.</span><span class="n">__name__</span> <span class="o">=</span> <span class="n">method</span><span class="o">.</span><span class="n">__name__</span>
<span class="n">manager_method</span><span class="o">.</span><span class="n">__doc__</span> <span class="o">=</span> <span class="n">method</span><span class="o">.</span><span class="n">__doc__</span>
<span class="k">return</span> <span class="n">manager_method</span>
<span class="n">new_methods</span> <span class="o">=</span> <span class="p">{}</span>
<span class="c1"># Refs http://bugs.python.org/issue1785.</span>
<span class="n">predicate</span> <span class="o">=</span> <span class="n">inspect</span><span class="o">.</span><span class="n">isfunction</span> <span class="k">if</span> <span class="n">six</span><span class="o">.</span><span class="n">PY3</span> <span class="k">else</span> <span class="n">inspect</span><span class="o">.</span><span class="n">ismethod</span>
<span class="k">for</span> <span class="n">name</span><span class="p">,</span> <span class="n">method</span> <span class="ow">in</span> <span class="n">inspect</span><span class="o">.</span><span class="n">getmembers</span><span class="p">(</span><span class="n">queryset_class</span><span class="p">,</span> <span class="n">predicate</span><span class="o">=</span><span class="n">predicate</span><span class="p">):</span>
<span class="c1"># Only copy missing methods.</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">cls</span><span class="p">,</span> <span class="n">name</span><span class="p">):</span>
<span class="k">continue</span>
<span class="c1"># Only copy public methods or methods with the attribute `queryset_only=False`.</span>
<span class="n">queryset_only</span> <span class="o">=</span> <span class="nb">getattr</span><span class="p">(</span><span class="n">method</span><span class="p">,</span> <span class="s1">'queryset_only'</span><span class="p">,</span> <span class="kc">None</span><span class="p">)</span>
<span class="k">if</span> <span class="n">queryset_only</span> <span class="ow">or</span> <span class="p">(</span><span class="n">queryset_only</span> <span class="ow">is</span> <span class="kc">None</span> <span class="ow">and</span> <span class="n">name</span><span class="o">.</span><span class="n">startswith</span><span class="p">(</span><span class="s1">'_'</span><span class="p">)):</span>
<span class="k">continue</span>
<span class="c1"># Copy the method onto the manager.</span>
<span class="n">new_methods</span><span class="p">[</span><span class="n">name</span><span class="p">]</span> <span class="o">=</span> <span class="n">create_method</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">method</span><span class="p">)</span>
<span class="k">return</span> <span class="n">new_methods</span>
<span class="nd">@classmethod</span>
<span class="k">def</span> <span class="nf">from_queryset</span><span class="p">(</span><span class="n">cls</span><span class="p">,</span> <span class="n">queryset_class</span><span class="p">,</span> <span class="n">class_name</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="k">if</span> <span class="n">class_name</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="n">class_name</span> <span class="o">=</span> <span class="s1">'</span><span class="si">%s</span><span class="s1">From</span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span><span class="n">cls</span><span class="o">.</span><span class="n">__name__</span><span class="p">,</span> <span class="n">queryset_class</span><span class="o">.</span><span class="n">__name__</span><span class="p">)</span>
<span class="n">class_dict</span> <span class="o">=</span> <span class="p">{</span>
<span class="s1">'_queryset_class'</span><span class="p">:</span> <span class="n">queryset_class</span><span class="p">,</span>
<span class="p">}</span>
<span class="n">class_dict</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">cls</span><span class="o">.</span><span class="n">_get_queryset_methods</span><span class="p">(</span><span class="n">queryset_class</span><span class="p">))</span>
<span class="k">return</span> <span class="nb">type</span><span class="p">(</span><span class="n">class_name</span><span class="p">,</span> <span class="p">(</span><span class="n">cls</span><span class="p">,),</span> <span class="n">class_dict</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">contribute_to_class</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">model</span><span class="p">,</span> <span class="n">name</span><span class="p">):</span>
<span class="c1"># TODO: Use weakref because of possible memory leak / circular reference.</span>
<span class="bp">self</span><span class="o">.</span><span class="n">model</span> <span class="o">=</span> <span class="n">model</span>
<span class="k">if</span> <span class="ow">not</span> <span class="bp">self</span><span class="o">.</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="c1"># Only contribute the manager if the model is concrete</span>
<span class="k">if</span> <span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">abstract</span><span class="p">:</span>
<span class="nb">setattr</span><span class="p">(</span><span class="n">model</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">AbstractManagerDescriptor</span><span class="p">(</span><span class="n">model</span><span class="p">))</span>
<span class="k">elif</span> <span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">swapped</span><span class="p">:</span>
<span class="nb">setattr</span><span class="p">(</span><span class="n">model</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">SwappedManagerDescriptor</span><span class="p">(</span><span class="n">model</span><span class="p">))</span>
<span class="k">else</span><span class="p">:</span>
<span class="c1"># if not model._meta.abstract and not model._meta.swapped:</span>
<span class="nb">setattr</span><span class="p">(</span><span class="n">model</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">ManagerDescriptor</span><span class="p">(</span><span class="bp">self</span><span class="p">))</span>
<span class="k">if</span> <span class="p">(</span><span class="ow">not</span> <span class="nb">getattr</span><span class="p">(</span><span class="n">model</span><span class="p">,</span> <span class="s1">'_default_manager'</span><span class="p">,</span> <span class="kc">None</span><span class="p">)</span> <span class="ow">or</span>
<span class="bp">self</span><span class="o">.</span><span class="n">creation_counter</span> <span class="o"><</span> <span class="n">model</span><span class="o">.</span><span class="n">_default_manager</span><span class="o">.</span><span class="n">creation_counter</span><span class="p">):</span>
<span class="n">model</span><span class="o">.</span><span class="n">_default_manager</span> <span class="o">=</span> <span class="bp">self</span>
<span class="n">abstract</span> <span class="o">=</span> <span class="kc">False</span>
<span class="k">if</span> <span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">abstract</span> <span class="ow">or</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">_inherited</span> <span class="ow">and</span> <span class="ow">not</span> <span class="bp">self</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">proxy</span><span class="p">):</span>
<span class="n">abstract</span> <span class="o">=</span> <span class="kc">True</span>
<span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">managers</span><span class="o">.</span><span class="n">append</span><span class="p">((</span><span class="bp">self</span><span class="o">.</span><span class="n">creation_counter</span><span class="p">,</span> <span class="bp">self</span><span class="p">,</span> <span class="n">abstract</span><span class="p">))</span>
<span class="k">def</span> <span class="nf">_set_creation_counter</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Sets the creation counter value for this instance and increments the</span>
<span class="sd"> class-level copy.</span>
<span class="sd"> """</span>
<span class="bp">self</span><span class="o">.</span><span class="n">creation_counter</span> <span class="o">=</span> <span class="n">BaseManager</span><span class="o">.</span><span class="n">creation_counter</span>
<span class="n">BaseManager</span><span class="o">.</span><span class="n">creation_counter</span> <span class="o">+=</span> <span class="mi">1</span>
<span class="k">def</span> <span class="nf">_copy_to_model</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">model</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Makes a copy of the manager and assigns it to 'model', which should be</span>
<span class="sd"> a child of the existing model (used when inheriting a manager from an</span>
<span class="sd"> abstract base class).</span>
<span class="sd"> """</span>
<span class="k">assert</span> <span class="nb">issubclass</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">model</span><span class="p">)</span>
<span class="n">mgr</span> <span class="o">=</span> <span class="n">copy</span><span class="o">.</span><span class="n">copy</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span>
<span class="n">mgr</span><span class="o">.</span><span class="n">_set_creation_counter</span><span class="p">()</span>
<span class="n">mgr</span><span class="o">.</span><span class="n">model</span> <span class="o">=</span> <span class="n">model</span>
<span class="n">mgr</span><span class="o">.</span><span class="n">_inherited</span> <span class="o">=</span> <span class="kc">True</span>
<span class="k">return</span> <span class="n">mgr</span>
<span class="k">def</span> <span class="nf">db_manager</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">using</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">hints</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="n">obj</span> <span class="o">=</span> <span class="n">copy</span><span class="o">.</span><span class="n">copy</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span>
<span class="n">obj</span><span class="o">.</span><span class="n">_db</span> <span class="o">=</span> <span class="n">using</span> <span class="ow">or</span> <span class="bp">self</span><span class="o">.</span><span class="n">_db</span>
<span class="n">obj</span><span class="o">.</span><span class="n">_hints</span> <span class="o">=</span> <span class="n">hints</span> <span class="ow">or</span> <span class="bp">self</span><span class="o">.</span><span class="n">_hints</span>
<span class="k">return</span> <span class="n">obj</span>
<span class="nd">@property</span>
<span class="k">def</span> <span class="nf">db</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_db</span> <span class="ow">or</span> <span class="n">router</span><span class="o">.</span><span class="n">db_for_read</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">model</span><span class="p">,</span> <span class="o">**</span><span class="bp">self</span><span class="o">.</span><span class="n">_hints</span><span class="p">)</span>
<span class="c1">#######################</span>
<span class="c1"># PROXIES TO QUERYSET #</span>
<span class="c1">#######################</span>
<span class="k">def</span> <span class="nf">get_queryset</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Returns a new QuerySet object. Subclasses can override this method to</span>
<span class="sd"> easily customize the behavior of the Manager.</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_queryset_class</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">model</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">_db</span><span class="p">,</span> <span class="n">hints</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">_hints</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">all</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="c1"># We can't proxy this method through the `QuerySet` like we do for the</span>
<span class="c1"># rest of the `QuerySet` methods. This is because `QuerySet.all()`</span>
<span class="c1"># works by creating a "copy" of the current queryset and in making said</span>
<span class="c1"># copy, all the cached `prefetch_related` lookups are lost. See the</span>
<span class="c1"># implementation of `RelatedManager.get_queryset()` for a better</span>
<span class="c1"># understanding of how this comes into play.</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_queryset</span><span class="p">()</span>
<span class="k">def</span> <span class="nf">__eq__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">other</span><span class="p">):</span>
<span class="k">return</span> <span class="p">(</span>
<span class="nb">isinstance</span><span class="p">(</span><span class="n">other</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">__class__</span><span class="p">)</span> <span class="ow">and</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_constructor_args</span> <span class="o">==</span> <span class="n">other</span><span class="o">.</span><span class="n">_constructor_args</span>
<span class="p">)</span>
<span class="k">def</span> <span class="nf">__ne__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">other</span><span class="p">):</span>
<span class="k">return</span> <span class="ow">not</span> <span class="p">(</span><span class="bp">self</span> <span class="o">==</span> <span class="n">other</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">__hash__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="nb">id</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span>
<div class="viewcode-block" id="Manager"><a class="viewcode-back" href="../../../../topics/db/managers.html#django.db.models.Manager">[docs]</a><span class="k">class</span> <span class="nc">Manager</span><span class="p">(</span><span class="n">BaseManager</span><span class="o">.</span><span class="n">from_queryset</span><span class="p">(</span><span class="n">QuerySet</span><span class="p">)):</span>
<span class="k">pass</span></div>
<span class="k">class</span> <span class="nc">ManagerDescriptor</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="c1"># This class ensures managers aren't accessible via model instances.</span>
<span class="c1"># For example, Poll.objects works, but poll_obj.objects raises AttributeError.</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">manager</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">manager</span> <span class="o">=</span> <span class="n">manager</span>
<span class="k">def</span> <span class="nf">__get__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">instance</span><span class="p">,</span> <span class="nb">type</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="k">if</span> <span class="n">instance</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">AttributeError</span><span class="p">(</span><span class="s2">"Manager isn't accessible via </span><span class="si">%s</span><span class="s2"> instances"</span> <span class="o">%</span> <span class="nb">type</span><span class="o">.</span><span class="n">__name__</span><span class="p">)</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">manager</span>
<span class="k">class</span> <span class="nc">AbstractManagerDescriptor</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="c1"># This class provides a better error message when you try to access a</span>
<span class="c1"># manager on an abstract model.</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">model</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">model</span> <span class="o">=</span> <span class="n">model</span>
<span class="k">def</span> <span class="nf">__get__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">instance</span><span class="p">,</span> <span class="nb">type</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="k">raise</span> <span class="ne">AttributeError</span><span class="p">(</span><span class="s2">"Manager isn't available; </span><span class="si">%s</span><span class="s2"> is abstract"</span> <span class="o">%</span> <span class="p">(</span>
<span class="bp">self</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">object_name</span><span class="p">,</span>
<span class="p">))</span>
<span class="k">class</span> <span class="nc">SwappedManagerDescriptor</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="c1"># This class provides a better error message when you try to access a</span>
<span class="c1"># manager on a swapped model.</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">model</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">model</span> <span class="o">=</span> <span class="n">model</span>
<span class="k">def</span> <span class="nf">__get__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">instance</span><span class="p">,</span> <span class="nb">type</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="k">raise</span> <span class="ne">AttributeError</span><span class="p">(</span><span class="s2">"Manager isn't available; </span><span class="si">%s</span><span class="s2"> has been swapped for '</span><span class="si">%s</span><span class="s2">'"</span> <span class="o">%</span> <span class="p">(</span>
<span class="bp">self</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">object_name</span><span class="p">,</span> <span class="bp">self</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">swapped</span>
<span class="p">))</span>
<span class="k">class</span> <span class="nc">EmptyManager</span><span class="p">(</span><span class="n">Manager</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">model</span><span class="p">):</span>
<span class="nb">super</span><span class="p">(</span><span class="n">EmptyManager</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="bp">self</span><span class="o">.</span><span class="n">model</span> <span class="o">=</span> <span class="n">model</span>
<span class="k">def</span> <span class="nf">get_queryset</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">EmptyManager</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">get_queryset</span><span class="p">()</span><span class="o">.</span><span class="n">none</span><span class="p">()</span>
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