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<h1>Source code for django.db.models.query_utils</h1><div class="highlight"><pre>
<span></span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd">Various data structures used in query construction.</span>
<span class="sd">Factored out from django.db.models.query to avoid making the main module very</span>
<span class="sd">large and/or so that they can be used by other modules without getting into</span>
<span class="sd">circular import difficulties.</span>
<span class="sd">&quot;&quot;&quot;</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">functools</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">inspect</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">logging</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">collections</span><span class="w"> </span><span class="kn">import</span> <span class="n">namedtuple</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">contextlib</span><span class="w"> </span><span class="kn">import</span> <span class="n">nullcontext</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.core.exceptions</span><span class="w"> </span><span class="kn">import</span> <span class="n">FieldError</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.db</span><span class="w"> </span><span class="kn">import</span> <span class="n">DEFAULT_DB_ALIAS</span><span class="p">,</span> <span class="n">DatabaseError</span><span class="p">,</span> <span class="n">connections</span><span class="p">,</span> <span class="n">models</span><span class="p">,</span> <span class="n">transaction</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.db.models.constants</span><span class="w"> </span><span class="kn">import</span> <span class="n">LOOKUP_SEP</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.utils</span><span class="w"> </span><span class="kn">import</span> <span class="n">tree</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.utils.functional</span><span class="w"> </span><span class="kn">import</span> <span class="n">cached_property</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.utils.hashable</span><span class="w"> </span><span class="kn">import</span> <span class="n">make_hashable</span>
<span class="n">logger</span> <span class="o">=</span> <span class="n">logging</span><span class="o">.</span><span class="n">getLogger</span><span class="p">(</span><span class="s2">&quot;django.db.models&quot;</span><span class="p">)</span>
<span class="c1"># PathInfo is used when converting lookups (fk__somecol). The contents</span>
<span class="c1"># describe the relation in Model terms (model Options and Fields for both</span>
<span class="c1"># sides of the relation. The join_field is the field backing the relation.</span>
<span class="n">PathInfo</span> <span class="o">=</span> <span class="n">namedtuple</span><span class="p">(</span>
<span class="s2">&quot;PathInfo&quot;</span><span class="p">,</span>
<span class="s2">&quot;from_opts to_opts target_fields join_field m2m direct filtered_relation&quot;</span><span class="p">,</span>
<span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">subclasses</span><span class="p">(</span><span class="bp">cls</span><span class="p">):</span>
<span class="k">yield</span> <span class="bp">cls</span>
<span class="k">for</span> <span class="n">subclass</span> <span class="ow">in</span> <span class="bp">cls</span><span class="o">.</span><span class="n">__subclasses__</span><span class="p">():</span>
<span class="k">yield from</span> <span class="n">subclasses</span><span class="p">(</span><span class="n">subclass</span><span class="p">)</span>
<div class="viewcode-block" id="Q">
<a class="viewcode-back" href="../../../../api/evennia.typeclasses.managers.html#evennia.commands.default.building.Q">[docs]</a>
<span class="k">class</span><span class="w"> </span><span class="nc">Q</span><span class="p">(</span><span class="n">tree</span><span class="o">.</span><span class="n">Node</span><span class="p">):</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Encapsulate filters as objects that can then be combined logically (using</span>
<span class="sd"> `&amp;` and `|`).</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="c1"># Connection types</span>
<span class="n">AND</span> <span class="o">=</span> <span class="s2">&quot;AND&quot;</span>
<span class="n">OR</span> <span class="o">=</span> <span class="s2">&quot;OR&quot;</span>
<span class="n">XOR</span> <span class="o">=</span> <span class="s2">&quot;XOR&quot;</span>
<span class="n">default</span> <span class="o">=</span> <span class="n">AND</span>
<span class="n">conditional</span> <span class="o">=</span> <span class="kc">True</span>
<span class="n">connectors</span> <span class="o">=</span> <span class="p">(</span><span class="kc">None</span><span class="p">,</span> <span class="n">AND</span><span class="p">,</span> <span class="n">OR</span><span class="p">,</span> <span class="n">XOR</span><span class="p">)</span>
<div class="viewcode-block" id="Q.__init__">
<a class="viewcode-back" href="../../../../api/evennia.typeclasses.managers.html#evennia.commands.default.building.Q.__init__">[docs]</a>
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</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="n">_connector</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">_negated</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="k">if</span> <span class="n">_connector</span> <span class="ow">not</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">connectors</span><span class="p">:</span>
<span class="n">connector_reprs</span> <span class="o">=</span> <span class="s2">&quot;, &quot;</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;</span><span class="si">{</span><span class="n">conn</span><span class="si">!r}</span><span class="s2">&quot;</span> <span class="k">for</span> <span class="n">conn</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">connectors</span><span class="p">[</span><span class="mi">1</span><span class="p">:])</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;_connector must be one of </span><span class="si">{</span><span class="n">connector_reprs</span><span class="si">}</span><span class="s2">, or None.&quot;</span><span class="p">)</span>
<span class="nb">super</span><span class="p">()</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span>
<span class="n">children</span><span class="o">=</span><span class="p">[</span><span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">*</span><span class="nb">sorted</span><span class="p">(</span><span class="n">kwargs</span><span class="o">.</span><span class="n">items</span><span class="p">())],</span>
<span class="n">connector</span><span class="o">=</span><span class="n">_connector</span><span class="p">,</span>
<span class="n">negated</span><span class="o">=</span><span class="n">_negated</span><span class="p">,</span>
<span class="p">)</span></div>
<span class="k">def</span><span class="w"> </span><span class="nf">_combine</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="n">conn</span><span class="p">):</span>
<span class="k">if</span> <span class="nb">getattr</span><span class="p">(</span><span class="n">other</span><span class="p">,</span> <span class="s2">&quot;conditional&quot;</span><span class="p">,</span> <span class="kc">False</span><span class="p">)</span> <span class="ow">is</span> <span class="kc">False</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">TypeError</span><span class="p">(</span><span class="n">other</span><span class="p">)</span>
<span class="k">if</span> <span class="ow">not</span> <span class="bp">self</span><span class="p">:</span>
<span class="k">return</span> <span class="n">other</span><span class="o">.</span><span class="n">copy</span><span class="p">()</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">other</span> <span class="ow">and</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">other</span><span class="p">,</span> <span class="n">Q</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">copy</span><span class="p">()</span>
<span class="n">obj</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="n">connector</span><span class="o">=</span><span class="n">conn</span><span class="p">)</span>
<span class="n">obj</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">conn</span><span class="p">)</span>
<span class="n">obj</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="n">other</span><span class="p">,</span> <span class="n">conn</span><span class="p">)</span>
<span class="k">return</span> <span class="n">obj</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__or__</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="bp">self</span><span class="o">.</span><span class="n">_combine</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">OR</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__and__</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="bp">self</span><span class="o">.</span><span class="n">_combine</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">AND</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__xor__</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="bp">self</span><span class="o">.</span><span class="n">_combine</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">XOR</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__invert__</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="bp">self</span><span class="o">.</span><span class="n">copy</span><span class="p">()</span>
<span class="n">obj</span><span class="o">.</span><span class="n">negate</span><span class="p">()</span>
<span class="k">return</span> <span class="n">obj</span>
<div class="viewcode-block" id="Q.resolve_expression">
<a class="viewcode-back" href="../../../../api/evennia.typeclasses.managers.html#evennia.commands.default.building.Q.resolve_expression">[docs]</a>
<span class="k">def</span><span class="w"> </span><span class="nf">resolve_expression</span><span class="p">(</span>
<span class="bp">self</span><span class="p">,</span> <span class="n">query</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">allow_joins</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span> <span class="n">reuse</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">summarize</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="n">for_save</span><span class="o">=</span><span class="kc">False</span>
<span class="p">):</span>
<span class="c1"># We must promote any new joins to left outer joins so that when Q is</span>
<span class="c1"># used as an expression, rows aren&#39;t filtered due to joins.</span>
<span class="n">clause</span><span class="p">,</span> <span class="n">joins</span> <span class="o">=</span> <span class="n">query</span><span class="o">.</span><span class="n">_add_q</span><span class="p">(</span>
<span class="bp">self</span><span class="p">,</span>
<span class="n">reuse</span><span class="p">,</span>
<span class="n">allow_joins</span><span class="o">=</span><span class="n">allow_joins</span><span class="p">,</span>
<span class="n">split_subq</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span>
<span class="n">check_filterable</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span>
<span class="n">summarize</span><span class="o">=</span><span class="n">summarize</span><span class="p">,</span>
<span class="p">)</span>
<span class="n">query</span><span class="o">.</span><span class="n">promote_joins</span><span class="p">(</span><span class="n">joins</span><span class="p">)</span>
<span class="k">return</span> <span class="n">clause</span></div>
<div class="viewcode-block" id="Q.replace_expressions">
<a class="viewcode-back" href="../../../../api/evennia.typeclasses.managers.html#evennia.commands.default.building.Q.replace_expressions">[docs]</a>
<span class="k">def</span><span class="w"> </span><span class="nf">replace_expressions</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">replacements</span><span class="p">):</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">replacements</span><span class="p">:</span>
<span class="k">return</span> <span class="bp">self</span>
<span class="n">clone</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="n">connector</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">connector</span><span class="p">,</span> <span class="n">negated</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">negated</span><span class="p">)</span>
<span class="k">for</span> <span class="n">child</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">children</span><span class="p">:</span>
<span class="n">child_replacement</span> <span class="o">=</span> <span class="n">child</span>
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">child</span><span class="p">,</span> <span class="nb">tuple</span><span class="p">):</span>
<span class="n">lhs</span><span class="p">,</span> <span class="n">rhs</span> <span class="o">=</span> <span class="n">child</span>
<span class="k">if</span> <span class="n">LOOKUP_SEP</span> <span class="ow">in</span> <span class="n">lhs</span><span class="p">:</span>
<span class="n">path</span><span class="p">,</span> <span class="n">lookup</span> <span class="o">=</span> <span class="n">lhs</span><span class="o">.</span><span class="n">rsplit</span><span class="p">(</span><span class="n">LOOKUP_SEP</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">path</span> <span class="o">=</span> <span class="n">lhs</span>
<span class="n">lookup</span> <span class="o">=</span> <span class="kc">None</span>
<span class="n">field</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">F</span><span class="p">(</span><span class="n">path</span><span class="p">)</span>
<span class="k">if</span> <span class="p">(</span>
<span class="n">field_replacement</span> <span class="o">:=</span> <span class="n">field</span><span class="o">.</span><span class="n">replace_expressions</span><span class="p">(</span><span class="n">replacements</span><span class="p">)</span>
<span class="p">)</span> <span class="ow">is</span> <span class="ow">not</span> <span class="n">field</span><span class="p">:</span>
<span class="c1"># Handle the implicit __exact case by falling back to an</span>
<span class="c1"># extra transform when get_lookup returns no match for the</span>
<span class="c1"># last component of the path.</span>
<span class="k">if</span> <span class="n">lookup</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="n">lookup</span> <span class="o">=</span> <span class="s2">&quot;exact&quot;</span>
<span class="k">if</span> <span class="p">(</span><span class="n">lookup_class</span> <span class="o">:=</span> <span class="n">field_replacement</span><span class="o">.</span><span class="n">get_lookup</span><span class="p">(</span><span class="n">lookup</span><span class="p">))</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">if</span> <span class="p">(</span>
<span class="n">transform_class</span> <span class="o">:=</span> <span class="n">field_replacement</span><span class="o">.</span><span class="n">get_transform</span><span class="p">(</span><span class="n">lookup</span><span class="p">)</span>
<span class="p">)</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="n">field_replacement</span> <span class="o">=</span> <span class="n">transform_class</span><span class="p">(</span><span class="n">field_replacement</span><span class="p">)</span>
<span class="n">lookup</span> <span class="o">=</span> <span class="s2">&quot;exact&quot;</span>
<span class="n">lookup_class</span> <span class="o">=</span> <span class="n">field_replacement</span><span class="o">.</span><span class="n">get_lookup</span><span class="p">(</span><span class="n">lookup</span><span class="p">)</span>
<span class="k">if</span> <span class="n">rhs</span> <span class="ow">is</span> <span class="kc">None</span> <span class="ow">and</span> <span class="n">lookup</span> <span class="o">==</span> <span class="s2">&quot;exact&quot;</span><span class="p">:</span>
<span class="n">lookup_class</span> <span class="o">=</span> <span class="n">field_replacement</span><span class="o">.</span><span class="n">get_lookup</span><span class="p">(</span><span class="s2">&quot;isnull&quot;</span><span class="p">)</span>
<span class="n">rhs</span> <span class="o">=</span> <span class="kc">True</span>
<span class="k">if</span> <span class="n">lookup_class</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="n">child_replacement</span> <span class="o">=</span> <span class="n">lookup_class</span><span class="p">(</span><span class="n">field_replacement</span><span class="p">,</span> <span class="n">rhs</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">child_replacement</span> <span class="o">=</span> <span class="n">child</span><span class="o">.</span><span class="n">replace_expressions</span><span class="p">(</span><span class="n">replacements</span><span class="p">)</span>
<span class="n">clone</span><span class="o">.</span><span class="n">children</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">child_replacement</span><span class="p">)</span>
<span class="k">return</span> <span class="n">clone</span></div>
<div class="viewcode-block" id="Q.flatten">
<a class="viewcode-back" href="../../../../api/evennia.typeclasses.managers.html#evennia.commands.default.building.Q.flatten">[docs]</a>
<span class="k">def</span><span class="w"> </span><span class="nf">flatten</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Recursively yield this Q object and all subexpressions, in depth-first</span>
<span class="sd"> order.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">yield</span> <span class="bp">self</span>
<span class="k">for</span> <span class="n">child</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">children</span><span class="p">:</span>
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">child</span><span class="p">,</span> <span class="nb">tuple</span><span class="p">):</span>
<span class="c1"># Use the lookup.</span>
<span class="n">child</span> <span class="o">=</span> <span class="n">child</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">child</span><span class="p">,</span> <span class="s2">&quot;flatten&quot;</span><span class="p">):</span>
<span class="k">yield from</span> <span class="n">child</span><span class="o">.</span><span class="n">flatten</span><span class="p">()</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">yield</span> <span class="n">child</span></div>
<div class="viewcode-block" id="Q.check">
<a class="viewcode-back" href="../../../../api/evennia.typeclasses.managers.html#evennia.commands.default.building.Q.check">[docs]</a>
<span class="k">def</span><span class="w"> </span><span class="nf">check</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">against</span><span class="p">,</span> <span class="n">using</span><span class="o">=</span><span class="n">DEFAULT_DB_ALIAS</span><span class="p">):</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Do a database query to check if the expressions of the Q instance</span>
<span class="sd"> matches against the expressions.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="c1"># Avoid circular imports.</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.db.models</span><span class="w"> </span><span class="kn">import</span> <span class="n">BooleanField</span><span class="p">,</span> <span class="n">Value</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.db.models.functions</span><span class="w"> </span><span class="kn">import</span> <span class="n">Coalesce</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.db.models.sql</span><span class="w"> </span><span class="kn">import</span> <span class="n">Query</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.db.models.sql.constants</span><span class="w"> </span><span class="kn">import</span> <span class="n">SINGLE</span>
<span class="n">query</span> <span class="o">=</span> <span class="n">Query</span><span class="p">(</span><span class="kc">None</span><span class="p">)</span>
<span class="k">for</span> <span class="n">name</span><span class="p">,</span> <span class="n">value</span> <span class="ow">in</span> <span class="n">against</span><span class="o">.</span><span class="n">items</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">value</span><span class="p">,</span> <span class="s2">&quot;resolve_expression&quot;</span><span class="p">):</span>
<span class="n">value</span> <span class="o">=</span> <span class="n">Value</span><span class="p">(</span><span class="n">value</span><span class="p">)</span>
<span class="n">query</span><span class="o">.</span><span class="n">add_annotation</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">select</span><span class="o">=</span><span class="kc">False</span><span class="p">)</span>
<span class="n">query</span><span class="o">.</span><span class="n">add_annotation</span><span class="p">(</span><span class="n">Value</span><span class="p">(</span><span class="mi">1</span><span class="p">),</span> <span class="s2">&quot;_check&quot;</span><span class="p">)</span>
<span class="n">connection</span> <span class="o">=</span> <span class="n">connections</span><span class="p">[</span><span class="n">using</span><span class="p">]</span>
<span class="c1"># This will raise a FieldError if a field is missing in &quot;against&quot;.</span>
<span class="k">if</span> <span class="n">connection</span><span class="o">.</span><span class="n">features</span><span class="o">.</span><span class="n">supports_comparing_boolean_expr</span><span class="p">:</span>
<span class="n">query</span><span class="o">.</span><span class="n">add_q</span><span class="p">(</span><span class="n">Q</span><span class="p">(</span><span class="n">Coalesce</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="kc">True</span><span class="p">,</span> <span class="n">output_field</span><span class="o">=</span><span class="n">BooleanField</span><span class="p">())))</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">query</span><span class="o">.</span><span class="n">add_q</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span>
<span class="n">compiler</span> <span class="o">=</span> <span class="n">query</span><span class="o">.</span><span class="n">get_compiler</span><span class="p">(</span><span class="n">using</span><span class="o">=</span><span class="n">using</span><span class="p">)</span>
<span class="n">context_manager</span> <span class="o">=</span> <span class="p">(</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="n">using</span><span class="p">)</span>
<span class="k">if</span> <span class="n">connection</span><span class="o">.</span><span class="n">in_atomic_block</span>
<span class="k">else</span> <span class="n">nullcontext</span><span class="p">()</span>
<span class="p">)</span>
<span class="k">try</span><span class="p">:</span>
<span class="k">with</span> <span class="n">context_manager</span><span class="p">:</span>
<span class="k">return</span> <span class="n">compiler</span><span class="o">.</span><span class="n">execute_sql</span><span class="p">(</span><span class="n">SINGLE</span><span class="p">)</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span>
<span class="k">except</span> <span class="n">DatabaseError</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span>
<span class="n">logger</span><span class="o">.</span><span class="n">warning</span><span class="p">(</span><span class="s2">&quot;Got a database error calling check() on </span><span class="si">%r</span><span class="s2">: </span><span class="si">%s</span><span class="s2">&quot;</span><span class="p">,</span> <span class="bp">self</span><span class="p">,</span> <span class="n">e</span><span class="p">)</span>
<span class="k">return</span> <span class="kc">True</span></div>
<div class="viewcode-block" id="Q.deconstruct">
<a class="viewcode-back" href="../../../../api/evennia.typeclasses.managers.html#evennia.commands.default.building.Q.deconstruct">[docs]</a>
<span class="k">def</span><span class="w"> </span><span class="nf">deconstruct</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">path</span> <span class="o">=</span> <span class="s2">&quot;</span><span class="si">%s</span><span class="s2">.</span><span class="si">%s</span><span class="s2">&quot;</span> <span class="o">%</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="vm">__class__</span><span class="o">.</span><span class="vm">__module__</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="vm">__class__</span><span class="o">.</span><span class="vm">__name__</span><span class="p">)</span>
<span class="k">if</span> <span class="n">path</span><span class="o">.</span><span class="n">startswith</span><span class="p">(</span><span class="s2">&quot;django.db.models.query_utils&quot;</span><span class="p">):</span>
<span class="n">path</span> <span class="o">=</span> <span class="n">path</span><span class="o">.</span><span class="n">replace</span><span class="p">(</span><span class="s2">&quot;django.db.models.query_utils&quot;</span><span class="p">,</span> <span class="s2">&quot;django.db.models&quot;</span><span class="p">)</span>
<span class="n">args</span> <span class="o">=</span> <span class="nb">tuple</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">children</span><span class="p">)</span>
<span class="n">kwargs</span> <span class="o">=</span> <span class="p">{}</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">connector</span> <span class="o">!=</span> <span class="bp">self</span><span class="o">.</span><span class="n">default</span><span class="p">:</span>
<span class="n">kwargs</span><span class="p">[</span><span class="s2">&quot;_connector&quot;</span><span class="p">]</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">connector</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">negated</span><span class="p">:</span>
<span class="n">kwargs</span><span class="p">[</span><span class="s2">&quot;_negated&quot;</span><span class="p">]</span> <span class="o">=</span> <span class="kc">True</span>
<span class="k">return</span> <span class="n">path</span><span class="p">,</span> <span class="n">args</span><span class="p">,</span> <span class="n">kwargs</span></div>
<span class="nd">@cached_property</span>
<span class="k">def</span><span class="w"> </span><span class="nf">identity</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">path</span><span class="p">,</span> <span class="n">args</span><span class="p">,</span> <span class="n">kwargs</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">deconstruct</span><span class="p">()</span>
<span class="n">identity</span> <span class="o">=</span> <span class="p">[</span><span class="n">path</span><span class="p">,</span> <span class="o">*</span><span class="n">kwargs</span><span class="o">.</span><span class="n">items</span><span class="p">()]</span>
<span class="k">for</span> <span class="n">child</span> <span class="ow">in</span> <span class="n">args</span><span class="p">:</span>
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">child</span><span class="p">,</span> <span class="nb">tuple</span><span class="p">):</span>
<span class="n">arg</span><span class="p">,</span> <span class="n">value</span> <span class="o">=</span> <span class="n">child</span>
<span class="n">value</span> <span class="o">=</span> <span class="n">make_hashable</span><span class="p">(</span><span class="n">value</span><span class="p">)</span>
<span class="n">identity</span><span class="o">.</span><span class="n">append</span><span class="p">((</span><span class="n">arg</span><span class="p">,</span> <span class="n">value</span><span class="p">))</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">identity</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">child</span><span class="p">)</span>
<span class="k">return</span> <span class="nb">tuple</span><span class="p">(</span><span class="n">identity</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__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">if</span> <span class="ow">not</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">other</span><span class="p">,</span> <span class="n">Q</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">NotImplemented</span>
<span class="k">return</span> <span class="n">other</span><span class="o">.</span><span class="n">identity</span> <span class="o">==</span> <span class="bp">self</span><span class="o">.</span><span class="n">identity</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__hash__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="nb">hash</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">identity</span><span class="p">)</span>
<span class="nd">@cached_property</span>
<span class="k">def</span><span class="w"> </span><span class="nf">referenced_base_fields</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Retrieve all base fields referenced directly or through F expressions</span>
<span class="sd"> excluding any fields referenced through joins.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="c1"># Avoid circular imports.</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.db.models.sql</span><span class="w"> </span><span class="kn">import</span> <span class="n">query</span>
<span class="k">return</span> <span class="p">{</span>
<span class="n">child</span><span class="o">.</span><span class="n">split</span><span class="p">(</span><span class="n">LOOKUP_SEP</span><span class="p">,</span> <span class="mi">1</span><span class="p">)[</span><span class="mi">0</span><span class="p">]</span> <span class="k">for</span> <span class="n">child</span> <span class="ow">in</span> <span class="n">query</span><span class="o">.</span><span class="n">get_children_from_q</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span>
<span class="p">}</span></div>
<span class="k">class</span><span class="w"> </span><span class="nc">DeferredAttribute</span><span class="p">:</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> A wrapper for a deferred-loading field. When the value is read from this</span>
<span class="sd"> object the first time, the query is executed.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</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="bp">self</span><span class="o">.</span><span class="n">field</span> <span class="o">=</span> <span class="n">field</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__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="bp">cls</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Retrieve and caches the value from the datastore on the first lookup.</span>
<span class="sd"> Return the cached value.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">if</span> <span class="n">instance</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">return</span> <span class="bp">self</span>
<span class="n">data</span> <span class="o">=</span> <span class="n">instance</span><span class="o">.</span><span class="vm">__dict__</span>
<span class="n">field_name</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">field</span><span class="o">.</span><span class="n">attname</span>
<span class="k">if</span> <span class="n">field_name</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">data</span><span class="p">:</span>
<span class="c1"># Let&#39;s see if the field is part of the parent chain. If so we</span>
<span class="c1"># might be able to reuse the already loaded value. Refs #18343.</span>
<span class="n">val</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_check_parent_chain</span><span class="p">(</span><span class="n">instance</span><span class="p">)</span>
<span class="k">if</span> <span class="n">val</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">instance</span><span class="o">.</span><span class="n">_is_pk_set</span><span class="p">():</span>
<span class="k">raise</span> <span class="ne">AttributeError</span><span class="p">(</span>
<span class="sa">f</span><span class="s2">&quot;Cannot retrieve deferred field </span><span class="si">{</span><span class="n">field_name</span><span class="si">!r}</span><span class="s2"> &quot;</span>
<span class="s2">&quot;from an unsaved model.&quot;</span>
<span class="p">)</span>
<span class="n">instance</span><span class="o">.</span><span class="n">refresh_from_db</span><span class="p">(</span><span class="n">fields</span><span class="o">=</span><span class="p">[</span><span class="n">field_name</span><span class="p">])</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">data</span><span class="p">[</span><span class="n">field_name</span><span class="p">]</span> <span class="o">=</span> <span class="n">val</span>
<span class="k">return</span> <span class="n">data</span><span class="p">[</span><span class="n">field_name</span><span class="p">]</span>
<span class="k">def</span><span class="w"> </span><span class="nf">_check_parent_chain</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="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Check if the field value can be fetched from a parent field already</span>
<span class="sd"> loaded in the instance. This can be done if the to-be fetched</span>
<span class="sd"> field is a primary key field.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="n">opts</span> <span class="o">=</span> <span class="n">instance</span><span class="o">.</span><span class="n">_meta</span>
<span class="n">link_field</span> <span class="o">=</span> <span class="n">opts</span><span class="o">.</span><span class="n">get_ancestor_link</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">field</span><span class="o">.</span><span class="n">model</span><span class="p">)</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">field</span><span class="o">.</span><span class="n">primary_key</span> <span class="ow">and</span> <span class="bp">self</span><span class="o">.</span><span class="n">field</span> <span class="o">!=</span> <span class="n">link_field</span><span class="p">:</span>
<span class="k">return</span> <span class="nb">getattr</span><span class="p">(</span><span class="n">instance</span><span class="p">,</span> <span class="n">link_field</span><span class="o">.</span><span class="n">attname</span><span class="p">)</span>
<span class="k">return</span> <span class="kc">None</span>
<span class="k">class</span><span class="w"> </span><span class="nc">class_or_instance_method</span><span class="p">:</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Hook used in RegisterLookupMixin to return partial functions depending on</span>
<span class="sd"> the caller type (instance or class of models.Field).</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">class_method</span><span class="p">,</span> <span class="n">instance_method</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">class_method</span> <span class="o">=</span> <span class="n">class_method</span>
<span class="bp">self</span><span class="o">.</span><span class="n">instance_method</span> <span class="o">=</span> <span class="n">instance_method</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__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="n">owner</span><span class="p">):</span>
<span class="k">if</span> <span class="n">instance</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">return</span> <span class="n">functools</span><span class="o">.</span><span class="n">partial</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">class_method</span><span class="p">,</span> <span class="n">owner</span><span class="p">)</span>
<span class="k">return</span> <span class="n">functools</span><span class="o">.</span><span class="n">partial</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">instance_method</span><span class="p">,</span> <span class="n">instance</span><span class="p">)</span>
<span class="k">class</span><span class="w"> </span><span class="nc">RegisterLookupMixin</span><span class="p">:</span>
<span class="k">def</span><span class="w"> </span><span class="nf">_get_lookup</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">lookup_name</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_lookups</span><span class="p">()</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="n">lookup_name</span><span class="p">,</span> <span class="kc">None</span><span class="p">)</span>
<span class="nd">@functools</span><span class="o">.</span><span class="n">cache</span>
<span class="k">def</span><span class="w"> </span><span class="nf">get_class_lookups</span><span class="p">(</span><span class="bp">cls</span><span class="p">):</span>
<span class="n">class_lookups</span> <span class="o">=</span> <span class="p">[</span>
<span class="n">parent</span><span class="o">.</span><span class="vm">__dict__</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="s2">&quot;class_lookups&quot;</span><span class="p">,</span> <span class="p">{})</span> <span class="k">for</span> <span class="n">parent</span> <span class="ow">in</span> <span class="n">inspect</span><span class="o">.</span><span class="n">getmro</span><span class="p">(</span><span class="bp">cls</span><span class="p">)</span>
<span class="p">]</span>
<span class="k">return</span> <span class="bp">cls</span><span class="o">.</span><span class="n">merge_dicts</span><span class="p">(</span><span class="n">class_lookups</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">get_instance_lookups</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">class_lookups</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_class_lookups</span><span class="p">()</span>
<span class="k">if</span> <span class="n">instance_lookups</span> <span class="o">:=</span> <span class="nb">getattr</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="s2">&quot;instance_lookups&quot;</span><span class="p">,</span> <span class="kc">None</span><span class="p">):</span>
<span class="k">return</span> <span class="p">{</span><span class="o">**</span><span class="n">class_lookups</span><span class="p">,</span> <span class="o">**</span><span class="n">instance_lookups</span><span class="p">}</span>
<span class="k">return</span> <span class="n">class_lookups</span>
<span class="n">get_lookups</span> <span class="o">=</span> <span class="n">class_or_instance_method</span><span class="p">(</span><span class="n">get_class_lookups</span><span class="p">,</span> <span class="n">get_instance_lookups</span><span class="p">)</span>
<span class="n">get_class_lookups</span> <span class="o">=</span> <span class="nb">classmethod</span><span class="p">(</span><span class="n">get_class_lookups</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">get_lookup</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">lookup_name</span><span class="p">):</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.db.models.lookups</span><span class="w"> </span><span class="kn">import</span> <span class="n">Lookup</span>
<span class="n">found</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_get_lookup</span><span class="p">(</span><span class="n">lookup_name</span><span class="p">)</span>
<span class="k">if</span> <span class="n">found</span> <span class="ow">is</span> <span class="kc">None</span> <span class="ow">and</span> <span class="nb">hasattr</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="s2">&quot;output_field&quot;</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">output_field</span><span class="o">.</span><span class="n">get_lookup</span><span class="p">(</span><span class="n">lookup_name</span><span class="p">)</span>
<span class="k">if</span> <span class="n">found</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="nb">issubclass</span><span class="p">(</span><span class="n">found</span><span class="p">,</span> <span class="n">Lookup</span><span class="p">):</span>
<span class="k">return</span> <span class="kc">None</span>
<span class="k">return</span> <span class="n">found</span>
<span class="k">def</span><span class="w"> </span><span class="nf">get_transform</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">lookup_name</span><span class="p">):</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">django.db.models.lookups</span><span class="w"> </span><span class="kn">import</span> <span class="n">Transform</span>
<span class="n">found</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_get_lookup</span><span class="p">(</span><span class="n">lookup_name</span><span class="p">)</span>
<span class="k">if</span> <span class="n">found</span> <span class="ow">is</span> <span class="kc">None</span> <span class="ow">and</span> <span class="nb">hasattr</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="s2">&quot;output_field&quot;</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">output_field</span><span class="o">.</span><span class="n">get_transform</span><span class="p">(</span><span class="n">lookup_name</span><span class="p">)</span>
<span class="k">if</span> <span class="n">found</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="nb">issubclass</span><span class="p">(</span><span class="n">found</span><span class="p">,</span> <span class="n">Transform</span><span class="p">):</span>
<span class="k">return</span> <span class="kc">None</span>
<span class="k">return</span> <span class="n">found</span>
<span class="nd">@staticmethod</span>
<span class="k">def</span><span class="w"> </span><span class="nf">merge_dicts</span><span class="p">(</span><span class="n">dicts</span><span class="p">):</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Merge dicts in reverse to preference the order of the original list.</span>
<span class="sd"> e.g., merge_dicts([a, b]) will preference the keys in &#39;a&#39; over those in</span>
<span class="sd"> &#39;b&#39;.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="n">merged</span> <span class="o">=</span> <span class="p">{}</span>
<span class="k">for</span> <span class="n">d</span> <span class="ow">in</span> <span class="nb">reversed</span><span class="p">(</span><span class="n">dicts</span><span class="p">):</span>
<span class="n">merged</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">d</span><span class="p">)</span>
<span class="k">return</span> <span class="n">merged</span>
<span class="nd">@classmethod</span>
<span class="k">def</span><span class="w"> </span><span class="nf">_clear_cached_class_lookups</span><span class="p">(</span><span class="bp">cls</span><span class="p">):</span>
<span class="k">for</span> <span class="n">subclass</span> <span class="ow">in</span> <span class="n">subclasses</span><span class="p">(</span><span class="bp">cls</span><span class="p">):</span>
<span class="n">subclass</span><span class="o">.</span><span class="n">get_class_lookups</span><span class="o">.</span><span class="n">cache_clear</span><span class="p">()</span>
<span class="k">def</span><span class="w"> </span><span class="nf">register_class_lookup</span><span class="p">(</span><span class="bp">cls</span><span class="p">,</span> <span class="n">lookup</span><span class="p">,</span> <span class="n">lookup_name</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="k">if</span> <span class="n">lookup_name</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="n">lookup_name</span> <span class="o">=</span> <span class="n">lookup</span><span class="o">.</span><span class="n">lookup_name</span>
<span class="k">if</span> <span class="s2">&quot;class_lookups&quot;</span> <span class="ow">not</span> <span class="ow">in</span> <span class="bp">cls</span><span class="o">.</span><span class="vm">__dict__</span><span class="p">:</span>
<span class="bp">cls</span><span class="o">.</span><span class="n">class_lookups</span> <span class="o">=</span> <span class="p">{}</span>
<span class="bp">cls</span><span class="o">.</span><span class="n">class_lookups</span><span class="p">[</span><span class="n">lookup_name</span><span class="p">]</span> <span class="o">=</span> <span class="n">lookup</span>
<span class="bp">cls</span><span class="o">.</span><span class="n">_clear_cached_class_lookups</span><span class="p">()</span>
<span class="k">return</span> <span class="n">lookup</span>
<span class="k">def</span><span class="w"> </span><span class="nf">register_instance_lookup</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">lookup</span><span class="p">,</span> <span class="n">lookup_name</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="k">if</span> <span class="n">lookup_name</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="n">lookup_name</span> <span class="o">=</span> <span class="n">lookup</span><span class="o">.</span><span class="n">lookup_name</span>
<span class="k">if</span> <span class="s2">&quot;instance_lookups&quot;</span> <span class="ow">not</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="vm">__dict__</span><span class="p">:</span>
<span class="bp">self</span><span class="o">.</span><span class="n">instance_lookups</span> <span class="o">=</span> <span class="p">{}</span>
<span class="bp">self</span><span class="o">.</span><span class="n">instance_lookups</span><span class="p">[</span><span class="n">lookup_name</span><span class="p">]</span> <span class="o">=</span> <span class="n">lookup</span>
<span class="k">return</span> <span class="n">lookup</span>
<span class="n">register_lookup</span> <span class="o">=</span> <span class="n">class_or_instance_method</span><span class="p">(</span>
<span class="n">register_class_lookup</span><span class="p">,</span> <span class="n">register_instance_lookup</span>
<span class="p">)</span>
<span class="n">register_class_lookup</span> <span class="o">=</span> <span class="nb">classmethod</span><span class="p">(</span><span class="n">register_class_lookup</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">_unregister_class_lookup</span><span class="p">(</span><span class="bp">cls</span><span class="p">,</span> <span class="n">lookup</span><span class="p">,</span> <span class="n">lookup_name</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Remove given lookup from cls lookups. For use in tests only as it&#39;s</span>
<span class="sd"> not thread-safe.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">if</span> <span class="n">lookup_name</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="n">lookup_name</span> <span class="o">=</span> <span class="n">lookup</span><span class="o">.</span><span class="n">lookup_name</span>
<span class="k">del</span> <span class="bp">cls</span><span class="o">.</span><span class="n">class_lookups</span><span class="p">[</span><span class="n">lookup_name</span><span class="p">]</span>
<span class="bp">cls</span><span class="o">.</span><span class="n">_clear_cached_class_lookups</span><span class="p">()</span>
<span class="k">def</span><span class="w"> </span><span class="nf">_unregister_instance_lookup</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">lookup</span><span class="p">,</span> <span class="n">lookup_name</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Remove given lookup from instance lookups. For use in tests only as</span>
<span class="sd"> it&#39;s not thread-safe.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">if</span> <span class="n">lookup_name</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="n">lookup_name</span> <span class="o">=</span> <span class="n">lookup</span><span class="o">.</span><span class="n">lookup_name</span>
<span class="k">del</span> <span class="bp">self</span><span class="o">.</span><span class="n">instance_lookups</span><span class="p">[</span><span class="n">lookup_name</span><span class="p">]</span>
<span class="n">_unregister_lookup</span> <span class="o">=</span> <span class="n">class_or_instance_method</span><span class="p">(</span>
<span class="n">_unregister_class_lookup</span><span class="p">,</span> <span class="n">_unregister_instance_lookup</span>
<span class="p">)</span>
<span class="n">_unregister_class_lookup</span> <span class="o">=</span> <span class="nb">classmethod</span><span class="p">(</span><span class="n">_unregister_class_lookup</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">select_related_descend</span><span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="n">restricted</span><span class="p">,</span> <span class="n">requested</span><span class="p">,</span> <span class="n">select_mask</span><span class="p">):</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Return whether `field` should be used to descend deeper for</span>
<span class="sd"> `select_related()` purposes.</span>
<span class="sd"> Arguments:</span>
<span class="sd"> * `field` - the field to be checked. Can be either a `Field` or</span>
<span class="sd"> `ForeignObjectRel` instance.</span>
<span class="sd"> * `restricted` - a boolean field, indicating if the field list has been</span>
<span class="sd"> manually restricted using a select_related() clause.</span>
<span class="sd"> * `requested` - the select_related() dictionary.</span>
<span class="sd"> * `select_mask` - the dictionary of selected fields.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="c1"># Only relationships can be descended.</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">field</span><span class="o">.</span><span class="n">remote_field</span><span class="p">:</span>
<span class="k">return</span> <span class="kc">False</span>
<span class="c1"># Forward MTI parent links should not be explicitly descended as they are</span>
<span class="c1"># always JOIN&#39;ed against (unless excluded by `select_mask`).</span>
<span class="k">if</span> <span class="nb">getattr</span><span class="p">(</span><span class="n">field</span><span class="o">.</span><span class="n">remote_field</span><span class="p">,</span> <span class="s2">&quot;parent_link&quot;</span><span class="p">,</span> <span class="kc">False</span><span class="p">):</span>
<span class="k">return</span> <span class="kc">False</span>
<span class="c1"># When `select_related()` is used without a `*requested` mask all</span>
<span class="c1"># relationships are descended unless they are nullable.</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">restricted</span><span class="p">:</span>
<span class="k">return</span> <span class="ow">not</span> <span class="n">field</span><span class="o">.</span><span class="n">null</span>
<span class="c1"># When `select_related(*requested)` is used only fields that are part of</span>
<span class="c1"># `requested` should be descended.</span>
<span class="k">if</span> <span class="n">field</span><span class="o">.</span><span class="n">name</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">requested</span><span class="p">:</span>
<span class="k">return</span> <span class="kc">False</span>
<span class="c1"># Prevent invalid usages of `select_related()` and `only()`/`defer()` such</span>
<span class="c1"># as `select_related(&quot;a&quot;).only(&quot;b&quot;)` and `select_related(&quot;a&quot;).defer(&quot;a&quot;)`.</span>
<span class="k">if</span> <span class="n">select_mask</span> <span class="ow">and</span> <span class="n">field</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">select_mask</span><span class="p">:</span>
<span class="k">raise</span> <span class="n">FieldError</span><span class="p">(</span>
<span class="sa">f</span><span class="s2">&quot;Field </span><span class="si">{</span><span class="n">field</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="si">}</span><span class="s2">.</span><span class="si">{</span><span class="n">field</span><span class="o">.</span><span class="n">name</span><span class="si">}</span><span class="s2"> cannot be both &quot;</span>
<span class="s2">&quot;deferred and traversed using select_related at the same time.&quot;</span>
<span class="p">)</span>
<span class="k">return</span> <span class="kc">True</span>
<span class="k">def</span><span class="w"> </span><span class="nf">refs_expression</span><span class="p">(</span><span class="n">lookup_parts</span><span class="p">,</span> <span class="n">annotations</span><span class="p">):</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Check if the lookup_parts contains references to the given annotations set.</span>
<span class="sd"> Because the LOOKUP_SEP is contained in the default annotation names, check</span>
<span class="sd"> each prefix of the lookup_parts for a match.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">for</span> <span class="n">n</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="n">lookup_parts</span><span class="p">)</span> <span class="o">+</span> <span class="mi">1</span><span class="p">):</span>
<span class="n">level_n_lookup</span> <span class="o">=</span> <span class="n">LOOKUP_SEP</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">lookup_parts</span><span class="p">[</span><span class="mi">0</span><span class="p">:</span><span class="n">n</span><span class="p">])</span>
<span class="k">if</span> <span class="n">annotations</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="n">level_n_lookup</span><span class="p">):</span>
<span class="k">return</span> <span class="n">level_n_lookup</span><span class="p">,</span> <span class="n">lookup_parts</span><span class="p">[</span><span class="n">n</span><span class="p">:]</span>
<span class="k">return</span> <span class="kc">None</span><span class="p">,</span> <span class="p">()</span>
<span class="k">def</span><span class="w"> </span><span class="nf">check_rel_lookup_compatibility</span><span class="p">(</span><span class="n">model</span><span class="p">,</span> <span class="n">target_opts</span><span class="p">,</span> <span class="n">field</span><span class="p">):</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd"> Check that self.model is compatible with target_opts. Compatibility</span>
<span class="sd"> is OK if:</span>
<span class="sd"> 1) model and opts match (where proxy inheritance is removed)</span>
<span class="sd"> 2) model is parent of opts&#39; model or the other way around</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">def</span><span class="w"> </span><span class="nf">check</span><span class="p">(</span><span class="n">opts</span><span class="p">):</span>
<span class="k">return</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="o">==</span> <span class="n">opts</span><span class="o">.</span><span class="n">concrete_model</span>
<span class="ow">or</span> <span class="n">opts</span><span class="o">.</span><span class="n">concrete_model</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">all_parents</span>
<span class="ow">or</span> <span class="n">model</span> <span class="ow">in</span> <span class="n">opts</span><span class="o">.</span><span class="n">all_parents</span>
<span class="p">)</span>
<span class="c1"># If the field is a primary key, then doing a query against the field&#39;s</span>
<span class="c1"># model is ok, too. Consider the case:</span>
<span class="c1"># class Restaurant(models.Model):</span>
<span class="c1"># place = OneToOneField(Place, primary_key=True):</span>
<span class="c1"># Restaurant.objects.filter(pk__in=Restaurant.objects.all()).</span>
<span class="c1"># If we didn&#39;t have the primary key check, then pk__in (== place__in) would</span>
<span class="c1"># give Place&#39;s opts as the target opts, but Restaurant isn&#39;t compatible</span>
<span class="c1"># with that. This logic applies only to primary keys, as when doing</span>
<span class="c1"># __in=qs, we are going to turn this into __in=qs.values(&#39;pk&#39;) later on.</span>
<span class="k">return</span> <span class="n">check</span><span class="p">(</span><span class="n">target_opts</span><span class="p">)</span> <span class="ow">or</span> <span class="p">(</span>
<span class="nb">getattr</span><span class="p">(</span><span class="n">field</span><span class="p">,</span> <span class="s2">&quot;primary_key&quot;</span><span class="p">,</span> <span class="kc">False</span><span class="p">)</span> <span class="ow">and</span> <span class="n">check</span><span class="p">(</span><span class="n">field</span><span class="o">.</span><span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="p">)</span>
<span class="p">)</span>
<span class="k">class</span><span class="w"> </span><span class="nc">FilteredRelation</span><span class="p">:</span>
<span class="w"> </span><span class="sd">&quot;&quot;&quot;Specify custom filtering in the ON clause of SQL joins.&quot;&quot;&quot;</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">relation_name</span><span class="p">,</span> <span class="o">*</span><span class="p">,</span> <span class="n">condition</span><span class="o">=</span><span class="n">Q</span><span class="p">()):</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">relation_name</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s2">&quot;relation_name cannot be empty.&quot;</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">relation_name</span> <span class="o">=</span> <span class="n">relation_name</span>
<span class="bp">self</span><span class="o">.</span><span class="n">alias</span> <span class="o">=</span> <span class="kc">None</span>
<span class="k">if</span> <span class="ow">not</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">condition</span><span class="p">,</span> <span class="n">Q</span><span class="p">):</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s2">&quot;condition argument must be a Q() instance.&quot;</span><span class="p">)</span>
<span class="c1"># .condition and .resolved_condition have to be stored independently</span>
<span class="c1"># as the former must remain unchanged for Join.__eq__ to remain stable</span>
<span class="c1"># and reusable even once their .filtered_relation are resolved.</span>
<span class="bp">self</span><span class="o">.</span><span class="n">condition</span> <span class="o">=</span> <span class="n">condition</span>
<span class="bp">self</span><span class="o">.</span><span class="n">resolved_condition</span> <span class="o">=</span> <span class="kc">None</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__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">if</span> <span class="ow">not</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="vm">__class__</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">NotImplemented</span>
<span class="k">return</span> <span class="p">(</span>
<span class="bp">self</span><span class="o">.</span><span class="n">relation_name</span> <span class="o">==</span> <span class="n">other</span><span class="o">.</span><span class="n">relation_name</span>
<span class="ow">and</span> <span class="bp">self</span><span class="o">.</span><span class="n">alias</span> <span class="o">==</span> <span class="n">other</span><span class="o">.</span><span class="n">alias</span>
<span class="ow">and</span> <span class="bp">self</span><span class="o">.</span><span class="n">condition</span> <span class="o">==</span> <span class="n">other</span><span class="o">.</span><span class="n">condition</span>
<span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">clone</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">clone</span> <span class="o">=</span> <span class="n">FilteredRelation</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">relation_name</span><span class="p">,</span> <span class="n">condition</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">condition</span><span class="p">)</span>
<span class="n">clone</span><span class="o">.</span><span class="n">alias</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">alias</span>
<span class="k">if</span> <span class="p">(</span><span class="n">resolved_condition</span> <span class="o">:=</span> <span class="bp">self</span><span class="o">.</span><span class="n">resolved_condition</span><span class="p">)</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="n">clone</span><span class="o">.</span><span class="n">resolved_condition</span> <span class="o">=</span> <span class="n">resolved_condition</span><span class="o">.</span><span class="n">clone</span><span class="p">()</span>
<span class="k">return</span> <span class="n">clone</span>
<span class="k">def</span><span class="w"> </span><span class="nf">relabeled_clone</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">change_map</span><span class="p">):</span>
<span class="n">clone</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">clone</span><span class="p">()</span>
<span class="k">if</span> <span class="n">resolved_condition</span> <span class="o">:=</span> <span class="n">clone</span><span class="o">.</span><span class="n">resolved_condition</span><span class="p">:</span>
<span class="n">clone</span><span class="o">.</span><span class="n">resolved_condition</span> <span class="o">=</span> <span class="n">resolved_condition</span><span class="o">.</span><span class="n">relabeled_clone</span><span class="p">(</span><span class="n">change_map</span><span class="p">)</span>
<span class="k">return</span> <span class="n">clone</span>
<span class="k">def</span><span class="w"> </span><span class="nf">resolve_expression</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">query</span><span class="p">,</span> <span class="n">reuse</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">clone</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">clone</span><span class="p">()</span>
<span class="n">clone</span><span class="o">.</span><span class="n">resolved_condition</span> <span class="o">=</span> <span class="n">query</span><span class="o">.</span><span class="n">build_filter</span><span class="p">(</span>
<span class="bp">self</span><span class="o">.</span><span class="n">condition</span><span class="p">,</span>
<span class="n">can_reuse</span><span class="o">=</span><span class="n">reuse</span><span class="p">,</span>
<span class="n">allow_joins</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span>
<span class="n">split_subq</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span>
<span class="n">update_join_types</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span>
<span class="p">)[</span><span class="mi">0</span><span class="p">]</span>
<span class="k">return</span> <span class="n">clone</span>
<span class="k">def</span><span class="w"> </span><span class="nf">as_sql</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span>
<span class="k">return</span> <span class="n">compiler</span><span class="o">.</span><span class="n">compile</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">resolved_condition</span><span class="p">)</span>
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