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id="_modules-django-db-models-aggregates"> <h1>Source code for django.db.models.aggregates</h1><div class="highlight"><pre> <span></span><span class="sd">"""</span> <span class="sd">Classes to represent the definitions of aggregate functions.</span> <span class="sd">"""</span> <span class="kn">from</span> <span class="nn">django.core.exceptions</span> <span class="k">import</span> <span class="n">FieldError</span> <span class="kn">from</span> <span class="nn">django.db.models.expressions</span> <span class="k">import</span> <span class="n">Func</span><span class="p">,</span> <span class="n">Star</span> <span class="kn">from</span> <span class="nn">django.db.models.fields</span> <span class="k">import</span> <span class="n">FloatField</span><span class="p">,</span> <span class="n">IntegerField</span> <span class="n">__all__</span> <span class="o">=</span> <span class="p">[</span> <span class="s1">'Aggregate'</span><span class="p">,</span> <span class="s1">'Avg'</span><span class="p">,</span> <span class="s1">'Count'</span><span class="p">,</span> <span class="s1">'Max'</span><span class="p">,</span> <span class="s1">'Min'</span><span class="p">,</span> <span class="s1">'StdDev'</span><span class="p">,</span> <span class="s1">'Sum'</span><span class="p">,</span> <span class="s1">'Variance'</span><span class="p">,</span> <span class="p">]</span> <div class="viewcode-block" id="Aggregate"><a class="viewcode-back" href="../../../../ref/models/expressions.html#django.db.models.Aggregate">[docs]</a><span class="k">class</span> <span class="nc">Aggregate</span><span class="p">(</span><span class="n">Func</span><span class="p">):</span> <span class="n">contains_aggregate</span> <span class="o">=</span> <span class="kc">True</span> <span class="n">name</span> <span class="o">=</span> <span class="kc">None</span> <span class="k">def</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="k">assert</span> <span class="nb">len</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">source_expressions</span><span class="p">)</span> <span class="o">==</span> <span class="mi">1</span> <span class="c1"># Aggregates are not allowed in UPDATE queries, so ignore for_save</span> <span class="n">c</span> <span class="o">=</span> <span class="nb">super</span><span class="p">(</span><span class="n">Aggregate</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">resolve_expression</span><span class="p">(</span><span class="n">query</span><span class="p">,</span> <span class="n">allow_joins</span><span class="p">,</span> <span class="n">reuse</span><span class="p">,</span> <span class="n">summarize</span><span class="p">)</span> <span class="k">if</span> <span class="n">c</span><span class="o">.</span><span class="n">source_expressions</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">contains_aggregate</span> <span class="ow">and</span> <span class="ow">not</span> <span class="n">summarize</span><span class="p">:</span> <span class="n">name</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">source_expressions</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">name</span> <span class="k">raise</span> <span class="n">FieldError</span><span class="p">(</span><span class="s2">"Cannot compute </span><span class="si">%s</span><span class="s2">('</span><span class="si">%s</span><span class="s2">'): '</span><span class="si">%s</span><span class="s2">' is an aggregate"</span> <span class="o">%</span> <span class="p">(</span> <span class="n">c</span><span class="o">.</span><span class="n">name</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">name</span><span class="p">))</span> <span class="n">c</span><span class="o">.</span><span class="n">_patch_aggregate</span><span class="p">(</span><span class="n">query</span><span class="p">)</span> <span class="c1"># backward-compatibility support</span> <span class="k">return</span> <span class="n">c</span> <span class="nd">@property</span> <span class="k">def</span> <span class="nf">input_field</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">source_expressions</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="nd">@property</span> <span class="k">def</span> <span class="nf">default_alias</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">source_expressions</span><span class="p">[</span><span class="mi">0</span><span class="p">],</span> <span class="s1">'name'</span><span class="p">):</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="o">%</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">source_expressions</span><span class="p">[</span><span class="mi">0</span><span class="p">]</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">lower</span><span class="p">())</span> <span class="k">raise</span> <span class="ne">TypeError</span><span class="p">(</span><span class="s2">"Complex expressions require an alias"</span><span class="p">)</span> <span class="k">def</span> <span class="nf">get_group_by_cols</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="k">return</span> <span class="p">[]</span> <span class="k">def</span> <span class="nf">_patch_aggregate</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="sd">"""</span> <span class="sd"> Helper method for patching 3rd party aggregates that do not yet support</span> <span class="sd"> the new way of subclassing. This method will be removed in Django 1.10.</span> <span class="sd"> add_to_query(query, alias, col, source, is_summary) will be defined on</span> <span class="sd"> legacy aggregates which, in turn, instantiates the SQL implementation of</span> <span class="sd"> the aggregate. In all the cases found, the general implementation of</span> <span class="sd"> add_to_query looks like:</span> <span class="sd"> def add_to_query(self, query, alias, col, source, is_summary):</span> <span class="sd"> klass = SQLImplementationAggregate</span> <span class="sd"> aggregate = klass(col, source=source, is_summary=is_summary, **self.extra)</span> <span class="sd"> query.aggregates[alias] = aggregate</span> <span class="sd"> By supplying a known alias, we can get the SQLAggregate out of the</span> <span class="sd"> aggregates dict, and use the sql_function and sql_template attributes</span> <span class="sd"> to patch *this* aggregate.</span> <span class="sd"> """</span> <span class="k">if</span> <span class="ow">not</span> <span class="nb">hasattr</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="s1">'add_to_query'</span><span class="p">)</span> <span class="ow">or</span> <span class="bp">self</span><span class="o">.</span><span class="n">function</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span> <span class="k">return</span> <span class="n">placeholder_alias</span> <span class="o">=</span> <span class="s2">"_XXXXXXXX_"</span> <span class="bp">self</span><span class="o">.</span><span class="n">add_to_query</span><span class="p">(</span><span class="n">query</span><span class="p">,</span> <span class="n">placeholder_alias</span><span class="p">,</span> <span class="kc">None</span><span class="p">,</span> <span class="kc">None</span><span class="p">,</span> <span class="kc">None</span><span class="p">)</span> <span class="n">sql_aggregate</span> <span class="o">=</span> <span class="n">query</span><span class="o">.</span><span class="n">aggregates</span><span class="o">.</span><span class="n">pop</span><span class="p">(</span><span class="n">placeholder_alias</span><span class="p">)</span> <span class="k">if</span> <span class="s1">'sql_function'</span> <span class="ow">not</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">extra</span> <span class="ow">and</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">sql_aggregate</span><span class="p">,</span> <span class="s1">'sql_function'</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">extra</span><span class="p">[</span><span class="s1">'function'</span><span class="p">]</span> <span class="o">=</span> <span class="n">sql_aggregate</span><span class="o">.</span><span class="n">sql_function</span> <span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">sql_aggregate</span><span class="p">,</span> <span class="s1">'sql_template'</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">extra</span><span class="p">[</span><span class="s1">'template'</span><span class="p">]</span> <span class="o">=</span> <span class="n">sql_aggregate</span><span class="o">.</span><span class="n">sql_template</span></div> <div class="viewcode-block" id="Avg"><a class="viewcode-back" href="../../../../ref/models/querysets.html#django.db.models.Avg">[docs]</a><span class="k">class</span> <span class="nc">Avg</span><span class="p">(</span><span class="n">Aggregate</span><span class="p">):</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'AVG'</span> <span class="n">name</span> <span class="o">=</span> <span class="s1">'Avg'</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">expression</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="nb">super</span><span class="p">(</span><span class="n">Avg</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">__init__</span><span class="p">(</span><span class="n">expression</span><span class="p">,</span> <span class="n">output_field</span><span class="o">=</span><span class="n">FloatField</span><span class="p">(),</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">convert_value</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">context</span><span class="p">):</span> <span class="k">if</span> <span class="n">value</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span> <span class="k">return</span> <span class="n">value</span> <span class="k">return</span> <span class="nb">float</span><span class="p">(</span><span class="n">value</span><span class="p">)</span></div> <div class="viewcode-block" id="Count"><a class="viewcode-back" href="../../../../ref/models/querysets.html#django.db.models.Count">[docs]</a><span class="k">class</span> <span class="nc">Count</span><span class="p">(</span><span class="n">Aggregate</span><span class="p">):</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'COUNT'</span> <span class="n">name</span> <span class="o">=</span> <span class="s1">'Count'</span> <span class="n">template</span> <span class="o">=</span> <span class="s1">'</span><span class="si">%(function)s</span><span class="s1">(</span><span class="si">%(distinct)s%(expressions)s</span><span class="s1">)'</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">expression</span><span class="p">,</span> <span class="n">distinct</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="k">if</span> <span class="n">expression</span> <span class="o">==</span> <span class="s1">'*'</span><span class="p">:</span> <span class="n">expression</span> <span class="o">=</span> <span class="n">Star</span><span class="p">()</span> <span class="nb">super</span><span class="p">(</span><span class="n">Count</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">__init__</span><span class="p">(</span> <span class="n">expression</span><span class="p">,</span> <span class="n">distinct</span><span class="o">=</span><span class="s1">'DISTINCT '</span> <span class="k">if</span> <span class="n">distinct</span> <span class="k">else</span> <span class="s1">''</span><span class="p">,</span> <span class="n">output_field</span><span class="o">=</span><span class="n">IntegerField</span><span class="p">(),</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">__repr__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="k">return</span> <span class="s2">"</span><span class="si">{}</span><span class="s2">(</span><span class="si">{}</span><span class="s2">, distinct=</span><span class="si">{}</span><span class="s2">)"</span><span class="o">.</span><span class="n">format</span><span class="p">(</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="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">arg_joiner</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="nb">str</span><span class="p">(</span><span class="n">arg</span><span class="p">)</span> <span class="k">for</span> <span class="n">arg</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">source_expressions</span><span class="p">),</span> <span class="s1">'False'</span> <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">extra</span><span class="p">[</span><span class="s1">'distinct'</span><span class="p">]</span> <span class="o">==</span> <span class="s1">''</span> <span class="k">else</span> <span class="s1">'True'</span><span class="p">,</span> <span class="p">)</span> <span class="k">def</span> <span class="nf">convert_value</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">context</span><span class="p">):</span> <span class="k">if</span> <span class="n">value</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span> <span class="k">return</span> <span class="mi">0</span> <span class="k">return</span> <span class="nb">int</span><span class="p">(</span><span class="n">value</span><span class="p">)</span></div> <div class="viewcode-block" id="Max"><a class="viewcode-back" href="../../../../ref/models/querysets.html#django.db.models.Max">[docs]</a><span class="k">class</span> <span class="nc">Max</span><span class="p">(</span><span class="n">Aggregate</span><span class="p">):</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'MAX'</span> <span class="n">name</span> <span class="o">=</span> <span class="s1">'Max'</span></div> <div class="viewcode-block" id="Min"><a class="viewcode-back" href="../../../../ref/models/querysets.html#django.db.models.Min">[docs]</a><span class="k">class</span> <span class="nc">Min</span><span class="p">(</span><span class="n">Aggregate</span><span class="p">):</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'MIN'</span> <span class="n">name</span> <span class="o">=</span> <span class="s1">'Min'</span></div> <div class="viewcode-block" id="StdDev"><a class="viewcode-back" href="../../../../ref/models/querysets.html#django.db.models.StdDev">[docs]</a><span class="k">class</span> <span class="nc">StdDev</span><span class="p">(</span><span class="n">Aggregate</span><span class="p">):</span> <span class="n">name</span> <span class="o">=</span> <span class="s1">'StdDev'</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">expression</span><span class="p">,</span> <span class="n">sample</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">function</span> <span class="o">=</span> <span class="s1">'STDDEV_SAMP'</span> <span class="k">if</span> <span class="n">sample</span> <span class="k">else</span> <span class="s1">'STDDEV_POP'</span> <span class="nb">super</span><span class="p">(</span><span class="n">StdDev</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">__init__</span><span class="p">(</span><span class="n">expression</span><span class="p">,</span> <span class="n">output_field</span><span class="o">=</span><span class="n">FloatField</span><span class="p">(),</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">__repr__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="k">return</span> <span class="s2">"</span><span class="si">{}</span><span class="s2">(</span><span class="si">{}</span><span class="s2">, sample=</span><span class="si">{}</span><span class="s2">)"</span><span class="o">.</span><span class="n">format</span><span class="p">(</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="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">arg_joiner</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="nb">str</span><span class="p">(</span><span class="n">arg</span><span class="p">)</span> <span class="k">for</span> <span class="n">arg</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">source_expressions</span><span class="p">),</span> <span class="s1">'False'</span> <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">function</span> <span class="o">==</span> <span class="s1">'STDDEV_POP'</span> <span class="k">else</span> <span class="s1">'True'</span><span class="p">,</span> <span class="p">)</span> <span class="k">def</span> <span class="nf">convert_value</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">context</span><span class="p">):</span> <span class="k">if</span> <span class="n">value</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span> <span class="k">return</span> <span class="n">value</span> <span class="k">return</span> <span class="nb">float</span><span class="p">(</span><span class="n">value</span><span class="p">)</span></div> <div class="viewcode-block" id="Sum"><a class="viewcode-back" href="../../../../ref/models/querysets.html#django.db.models.Sum">[docs]</a><span class="k">class</span> <span class="nc">Sum</span><span class="p">(</span><span class="n">Aggregate</span><span class="p">):</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'SUM'</span> <span class="n">name</span> <span class="o">=</span> <span class="s1">'Sum'</span></div> <div class="viewcode-block" id="Variance"><a class="viewcode-back" href="../../../../ref/models/querysets.html#django.db.models.Variance">[docs]</a><span class="k">class</span> <span class="nc">Variance</span><span class="p">(</span><span class="n">Aggregate</span><span class="p">):</span> <span class="n">name</span> <span class="o">=</span> <span class="s1">'Variance'</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">expression</span><span class="p">,</span> <span class="n">sample</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">function</span> <span class="o">=</span> <span class="s1">'VAR_SAMP'</span> <span class="k">if</span> <span class="n">sample</span> <span class="k">else</span> <span class="s1">'VAR_POP'</span> <span class="nb">super</span><span class="p">(</span><span class="n">Variance</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">__init__</span><span class="p">(</span><span class="n">expression</span><span class="p">,</span> <span class="n">output_field</span><span class="o">=</span><span class="n">FloatField</span><span class="p">(),</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">__repr__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="k">return</span> <span class="s2">"</span><span class="si">{}</span><span class="s2">(</span><span class="si">{}</span><span class="s2">, sample=</span><span class="si">{}</span><span class="s2">)"</span><span class="o">.</span><span class="n">format</span><span class="p">(</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="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">arg_joiner</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="nb">str</span><span class="p">(</span><span class="n">arg</span><span class="p">)</span> <span class="k">for</span> <span class="n">arg</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">source_expressions</span><span class="p">),</span> <span class="s1">'False'</span> <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">function</span> <span class="o">==</span> <span class="s1">'VAR_POP'</span> <span class="k">else</span> <span class="s1">'True'</span><span class="p">,</span> <span class="p">)</span> <span class="k">def</span> <span class="nf">convert_value</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">context</span><span class="p">):</span> <span class="k">if</span> <span class="n">value</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span> <span class="k">return</span> <span class="n">value</span> <span class="k">return</span> <span class="nb">float</span><span class="p">(</span><span class="n">value</span><span class="p">)</span></div> </pre></div> </div> 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