<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" lang=""> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>django.db.models.query_utils — Django 1.8.19 documentation</title> <link rel="stylesheet" href="../../../../_static/default.css" type="text/css" /> <link rel="stylesheet" href="../../../../_static/pygments.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../../../../', VERSION: '1.8.19', COLLAPSE_INDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true }; </script> <script type="text/javascript" src="../../../../_static/jquery.js"></script> <script type="text/javascript" src="../../../../_static/underscore.js"></script> <script type="text/javascript" src="../../../../_static/doctools.js"></script> <link rel="index" title="Index" href="../../../../genindex.html" /> <link rel="search" title="Search" href="../../../../search.html" /> <link rel="top" title="Django 1.8.19 documentation" href="../../../../contents.html" /> <link rel="up" title="django" href="../../../django.html" /> <script type="text/javascript" src="../../../../templatebuiltins.js"></script> <script type="text/javascript"> (function($) { if (!django_template_builtins) { // templatebuiltins.js missing, do nothing. return; } $(document).ready(function() { // Hyperlink Django template tags and filters var base = "../../../../ref/templates/builtins.html"; if (base == "#") { // Special case for builtins.html itself base = ""; } // Tags are keywords, class '.k' $("div.highlight\\-html\\+django span.k").each(function(i, elem) { var tagname = $(elem).text(); if ($.inArray(tagname, django_template_builtins.ttags) != -1) { var fragment = tagname.replace(/_/, '-'); $(elem).html("<a href='" + base + "#" + fragment + "'>" + tagname + "</a>"); } }); // Filters are functions, class '.nf' $("div.highlight\\-html\\+django span.nf").each(function(i, elem) { var filtername = $(elem).text(); if ($.inArray(filtername, django_template_builtins.tfilters) != -1) { var fragment = filtername.replace(/_/, '-'); $(elem).html("<a href='" + base + "#" + fragment + "'>" + filtername + "</a>"); } }); }); })(jQuery); </script> </head> <body role="document"> <div class="document"> <div id="custom-doc" class="yui-t6"> <div id="hd"> <h1><a href="../../../../index.html">Django 1.8.19 documentation</a></h1> <div id="global-nav"> <a title="Home page" href="../../../../index.html">Home</a> | <a title="Table of contents" href="../../../../contents.html">Table of contents</a> | <a title="Global index" href="../../../../genindex.html">Index</a> | <a title="Module index" href="../../../../py-modindex.html">Modules</a> </div> <div class="nav"> <a href="../../../index.html" title="Module code" accesskey="U">up</a></div> </div> <div id="bd"> <div id="yui-main"> <div class="yui-b"> <div class="yui-g" id="_modules-django-db-models-query_utils"> <h1>Source code for django.db.models.query_utils</h1><div class="highlight"><pre> <span></span><span class="sd">"""</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">"""</span> <span class="kn">from</span> <span class="nn">__future__</span> <span class="k">import</span> <span class="n">unicode_literals</span> <span class="kn">from</span> <span class="nn">collections</span> <span class="k">import</span> <span class="n">namedtuple</span> <span class="kn">from</span> <span class="nn">django.core.exceptions</span> <span class="k">import</span> <span class="n">FieldDoesNotExist</span> <span class="kn">from</span> <span class="nn">django.db.backends</span> <span class="k">import</span> <span class="n">utils</span> <span class="kn">from</span> <span class="nn">django.db.models.constants</span> <span class="k">import</span> <span class="n">LOOKUP_SEP</span> <span class="kn">from</span> <span class="nn">django.utils</span> <span class="k">import</span> <span class="n">six</span><span class="p">,</span> <span class="n">tree</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="s1">'PathInfo'</span><span class="p">,</span> <span class="s1">'from_opts to_opts target_fields join_field m2m direct'</span><span class="p">)</span> <span class="k">class</span> <span class="nc">InvalidQuery</span><span class="p">(</span><span class="ne">Exception</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> The query passed to raw isn't a safe query to use with raw.</span> <span class="sd"> """</span> <span class="k">pass</span> <span class="k">class</span> <span class="nc">QueryWrapper</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> A type that indicates the contents are an SQL fragment and the associate</span> <span class="sd"> parameters. Can be used to pass opaque data to a where-clause, for example.</span> <span class="sd"> """</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">sql</span><span class="p">,</span> <span class="n">params</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span> <span class="o">=</span> <span class="n">sql</span><span class="p">,</span> <span class="nb">list</span><span class="p">(</span><span class="n">params</span><span class="p">)</span> <span class="k">def</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="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">connection</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span> <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span> <div class="viewcode-block" id="Q"><a class="viewcode-back" href="../../../../ref/models/querysets.html#django.db.models.Q">[docs]</a><span class="k">class</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="sd">"""</span> <span class="sd"> Encapsulates filters as objects that can then be combined logically (using</span> <span class="sd"> `&` and `|`).</span> <span class="sd"> """</span> <span class="c1"># Connection types</span> <span class="n">AND</span> <span class="o">=</span> <span class="s1">'AND'</span> <span class="n">OR</span> <span class="o">=</span> <span class="s1">'OR'</span> <span class="n">default</span> <span class="o">=</span> <span class="n">AND</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="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="nb">super</span><span class="p">(</span><span class="n">Q</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">children</span><span class="o">=</span><span class="nb">list</span><span class="p">(</span><span class="n">args</span><span class="p">)</span> <span class="o">+</span> <span class="nb">list</span><span class="p">(</span><span class="n">six</span><span class="o">.</span><span class="n">iteritems</span><span class="p">(</span><span class="n">kwargs</span><span class="p">)))</span> <span class="k">def</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="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">raise</span> <span class="ne">TypeError</span><span class="p">(</span><span class="n">other</span><span class="p">)</span> <span class="n">obj</span> <span class="o">=</span> <span class="nb">type</span><span class="p">(</span><span class="bp">self</span><span class="p">)()</span> <span class="n">obj</span><span class="o">.</span><span class="n">connector</span> <span class="o">=</span> <span class="n">conn</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="nf">__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="nf">__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="nf">__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="nb">type</span><span class="p">(</span><span class="bp">self</span><span class="p">)()</span> <span class="n">obj</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="bp">self</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="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> <span class="k">def</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="bp">self</span><span class="o">.</span><span class="n">__class__</span><span class="o">.</span><span class="n">_new_instance</span><span class="p">(</span> <span class="n">children</span><span class="o">=</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="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">child</span><span class="p">,</span> <span class="s1">'clone'</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</span><span class="o">.</span><span class="n">clone</span><span class="p">())</span> <span class="k">else</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</span><span class="p">)</span> <span class="k">return</span> <span class="n">clone</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="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'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">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> <span class="nd">@classmethod</span> <span class="k">def</span> <span class="nf">_refs_aggregate</span><span class="p">(</span><span class="n">cls</span><span class="p">,</span> <span class="n">obj</span><span class="p">,</span> <span class="n">existing_aggregates</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">obj</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="n">aggregate</span><span class="p">,</span> <span class="n">aggregate_lookups</span> <span class="o">=</span> <span class="n">refs_aggregate</span><span class="p">(</span><span class="n">obj</span><span class="p">[</span><span class="mi">0</span><span class="p">]</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="n">existing_aggregates</span><span class="p">)</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">aggregate</span> <span class="ow">and</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">obj</span><span class="p">[</span><span class="mi">1</span><span class="p">],</span> <span class="s1">'refs_aggregate'</span><span class="p">):</span> <span class="k">return</span> <span class="n">obj</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span><span class="o">.</span><span class="n">refs_aggregate</span><span class="p">(</span><span class="n">existing_aggregates</span><span class="p">)</span> <span class="k">return</span> <span class="n">aggregate</span><span class="p">,</span> <span class="n">aggregate_lookups</span> <span class="k">for</span> <span class="n">c</span> <span class="ow">in</span> <span class="n">obj</span><span class="o">.</span><span class="n">children</span><span class="p">:</span> <span class="n">aggregate</span><span class="p">,</span> <span class="n">aggregate_lookups</span> <span class="o">=</span> <span class="n">cls</span><span class="o">.</span><span class="n">_refs_aggregate</span><span class="p">(</span><span class="n">c</span><span class="p">,</span> <span class="n">existing_aggregates</span><span class="p">)</span> <span class="k">if</span> <span class="n">aggregate</span><span class="p">:</span> <span class="k">return</span> <span class="n">aggregate</span><span class="p">,</span> <span class="n">aggregate_lookups</span> <span class="k">return</span> <span class="kc">False</span><span class="p">,</span> <span class="p">()</span> <span class="k">def</span> <span class="nf">refs_aggregate</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">existing_aggregates</span><span class="p">):</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">existing_aggregates</span><span class="p">:</span> <span class="k">return</span> <span class="kc">False</span> <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_refs_aggregate</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">existing_aggregates</span><span class="p">)</span></div> <span class="k">class</span> <span class="nc">DeferredAttribute</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span> <span class="sd">"""</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"> """</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">field_name</span><span class="p">,</span> <span class="n">model</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">field_name</span> <span class="o">=</span> <span class="n">field_name</span> <span class="k">def</span> <span class="nf">__get__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">instance</span><span class="p">,</span> <span class="n">owner</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Retrieves and caches the value from the datastore on the first lookup.</span> <span class="sd"> Returns the cached value.</span> <span class="sd"> """</span> <span class="n">non_deferred_model</span> <span class="o">=</span> <span class="n">instance</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">proxy_for_model</span> <span class="n">opts</span> <span class="o">=</span> <span class="n">non_deferred_model</span><span class="o">.</span><span class="n">_meta</span> <span class="k">assert</span> <span class="n">instance</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span> <span class="n">data</span> <span class="o">=</span> <span class="n">instance</span><span class="o">.</span><span class="n">__dict__</span> <span class="k">if</span> <span class="n">data</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">field_name</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span> <span class="ow">is</span> <span class="bp">self</span><span class="p">:</span> <span class="c1"># self.field_name is the attname of the field, but only() takes the</span> <span class="c1"># actual name, so we need to translate it here.</span> <span class="k">try</span><span class="p">:</span> <span class="n">f</span> <span class="o">=</span> <span class="n">opts</span><span class="o">.</span><span class="n">get_field</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">field_name</span><span class="p">)</span> <span class="k">except</span> <span class="n">FieldDoesNotExist</span><span class="p">:</span> <span class="n">f</span> <span class="o">=</span> <span class="p">[</span><span class="n">f</span> <span class="k">for</span> <span class="n">f</span> <span class="ow">in</span> <span class="n">opts</span><span class="o">.</span><span class="n">fields</span> <span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">attname</span> <span class="o">==</span> <span class="bp">self</span><span class="o">.</span><span class="n">field_name</span><span class="p">][</span><span class="mi">0</span><span class="p">]</span> <span class="n">name</span> <span class="o">=</span> <span class="n">f</span><span class="o">.</span><span class="n">name</span> <span class="c1"># Let'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="n">name</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="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="bp">self</span><span class="o">.</span><span class="n">field_name</span><span class="p">])</span> <span class="n">val</span> <span class="o">=</span> <span class="nb">getattr</span><span class="p">(</span><span class="n">instance</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">field_name</span><span class="p">)</span> <span class="n">data</span><span class="p">[</span><span class="bp">self</span><span class="o">.</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="bp">self</span><span class="o">.</span><span class="n">field_name</span><span class="p">]</span> <span class="k">def</span> <span class="nf">__set__</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">value</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Deferred loading attributes can be set normally (which means there will</span> <span class="sd"> never be a database lookup involved.</span> <span class="sd"> """</span> <span class="n">instance</span><span class="o">.</span><span class="n">__dict__</span><span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">field_name</span><span class="p">]</span> <span class="o">=</span> <span class="n">value</span> <span class="k">def</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="n">name</span><span class="p">):</span> <span class="sd">"""</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"> """</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">f</span> <span class="o">=</span> <span class="n">opts</span><span class="o">.</span><span class="n">get_field</span><span class="p">(</span><span class="n">name</span><span class="p">)</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="n">f</span><span class="o">.</span><span class="n">model</span><span class="p">)</span> <span class="k">if</span> <span class="n">f</span><span class="o">.</span><span class="n">primary_key</span> <span class="ow">and</span> <span class="n">f</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">def</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">load_fields</span><span class="p">,</span> <span class="n">reverse</span><span class="o">=</span><span class="kc">False</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Returns True if this field should be used to descend deeper for</span> <span class="sd"> select_related() purposes. Used by both the query construction code</span> <span class="sd"> (sql.query.fill_related_selections()) and the model instance creation code</span> <span class="sd"> (query.get_klass_info()).</span> <span class="sd"> Arguments:</span> <span class="sd"> * field - the field to be checked</span> <span class="sd"> * restricted - a boolean field, indicating if the field list has been</span> <span class="sd"> manually restricted using a requested clause)</span> <span class="sd"> * requested - The select_related() dictionary.</span> <span class="sd"> * load_fields - the set of fields to be loaded on this model</span> <span class="sd"> * reverse - boolean, True if we are checking a reverse select related</span> <span class="sd"> """</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">field</span><span class="o">.</span><span class="n">rel</span><span class="p">:</span> <span class="k">return</span> <span class="kc">False</span> <span class="k">if</span> <span class="n">field</span><span class="o">.</span><span class="n">rel</span><span class="o">.</span><span class="n">parent_link</span> <span class="ow">and</span> <span class="ow">not</span> <span class="n">reverse</span><span class="p">:</span> <span class="k">return</span> <span class="kc">False</span> <span class="k">if</span> <span class="n">restricted</span><span class="p">:</span> <span class="k">if</span> <span class="n">reverse</span> <span class="ow">and</span> <span class="n">field</span><span class="o">.</span><span class="n">related_query_name</span><span class="p">()</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="k">if</span> <span class="ow">not</span> <span class="n">reverse</span> <span class="ow">and</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="k">if</span> <span class="ow">not</span> <span class="n">restricted</span> <span class="ow">and</span> <span class="n">field</span><span class="o">.</span><span class="n">null</span><span class="p">:</span> <span class="k">return</span> <span class="kc">False</span> <span class="k">if</span> <span class="n">load_fields</span><span class="p">:</span> <span class="k">if</span> <span class="n">field</span><span class="o">.</span><span class="n">attname</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">load_fields</span><span class="p">:</span> <span class="k">if</span> <span class="n">restricted</span> <span class="ow">and</span> <span class="n">field</span><span class="o">.</span><span class="n">name</span> <span class="ow">in</span> <span class="n">requested</span><span class="p">:</span> <span class="k">raise</span> <span class="n">InvalidQuery</span><span class="p">(</span><span class="s2">"Field </span><span class="si">%s</span><span class="s2">.</span><span class="si">%s</span><span class="s2"> cannot be both deferred"</span> <span class="s2">" and traversed using select_related"</span> <span class="s2">" at the same time."</span> <span class="o">%</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="o">.</span><span class="n">object_name</span><span class="p">,</span> <span class="n">field</span><span class="o">.</span><span class="n">name</span><span class="p">))</span> <span class="k">return</span> <span class="kc">False</span> <span class="k">return</span> <span class="kc">True</span> <span class="c1"># This function is needed because data descriptors must be defined on a class</span> <span class="c1"># object, not an instance, to have any effect.</span> <span class="k">def</span> <span class="nf">deferred_class_factory</span><span class="p">(</span><span class="n">model</span><span class="p">,</span> <span class="n">attrs</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Returns a class object that is a copy of "model" with the specified "attrs"</span> <span class="sd"> being replaced with DeferredAttribute objects. The "pk_value" ties the</span> <span class="sd"> deferred attributes to a particular instance of the model.</span> <span class="sd"> """</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">attrs</span><span class="p">:</span> <span class="k">return</span> <span class="n">model</span> <span class="n">opts</span> <span class="o">=</span> <span class="n">model</span><span class="o">.</span><span class="n">_meta</span> <span class="c1"># Never create deferred models based on deferred model</span> <span class="k">if</span> <span class="n">model</span><span class="o">.</span><span class="n">_deferred</span><span class="p">:</span> <span class="c1"># Deferred models are proxies for the non-deferred model. We never</span> <span class="c1"># create chains of defers => proxy_for_model is the non-deferred</span> <span class="c1"># model.</span> <span class="n">model</span> <span class="o">=</span> <span class="n">opts</span><span class="o">.</span><span class="n">proxy_for_model</span> <span class="c1"># The app registry wants a unique name for each model, otherwise the new</span> <span class="c1"># class won't be created (we get an exception). Therefore, we generate</span> <span class="c1"># the name using the passed in attrs. It's OK to reuse an existing class</span> <span class="c1"># object if the attrs are identical.</span> <span class="n">name</span> <span class="o">=</span> <span class="s2">"</span><span class="si">%s</span><span class="s2">_Deferred_</span><span class="si">%s</span><span class="s2">"</span> <span class="o">%</span> <span class="p">(</span><span class="n">model</span><span class="o">.</span><span class="n">__name__</span><span class="p">,</span> <span class="s1">'_'</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="nb">sorted</span><span class="p">(</span><span class="nb">list</span><span class="p">(</span><span class="n">attrs</span><span class="p">))))</span> <span class="n">name</span> <span class="o">=</span> <span class="n">utils</span><span class="o">.</span><span class="n">truncate_name</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="mi">80</span><span class="p">,</span> <span class="mi">32</span><span class="p">)</span> <span class="k">try</span><span class="p">:</span> <span class="k">return</span> <span class="n">opts</span><span class="o">.</span><span class="n">apps</span><span class="o">.</span><span class="n">get_model</span><span class="p">(</span><span class="n">model</span><span class="o">.</span><span class="n">_meta</span><span class="o">.</span><span class="n">app_label</span><span class="p">,</span> <span class="n">name</span><span class="p">)</span> <span class="k">except</span> <span class="ne">LookupError</span><span class="p">:</span> <span class="k">class</span> <span class="nc">Meta</span><span class="p">:</span> <span class="n">proxy</span> <span class="o">=</span> <span class="kc">True</span> <span class="n">apps</span> <span class="o">=</span> <span class="n">opts</span><span class="o">.</span><span class="n">apps</span> <span class="n">app_label</span> <span class="o">=</span> <span class="n">opts</span><span class="o">.</span><span class="n">app_label</span> <span class="n">overrides</span> <span class="o">=</span> <span class="p">{</span><span class="n">attr</span><span class="p">:</span> <span class="n">DeferredAttribute</span><span class="p">(</span><span class="n">attr</span><span class="p">,</span> <span class="n">model</span><span class="p">)</span> <span class="k">for</span> <span class="n">attr</span> <span class="ow">in</span> <span class="n">attrs</span><span class="p">}</span> <span class="n">overrides</span><span class="p">[</span><span class="s2">"Meta"</span><span class="p">]</span> <span class="o">=</span> <span class="n">Meta</span> <span class="n">overrides</span><span class="p">[</span><span class="s2">"__module__"</span><span class="p">]</span> <span class="o">=</span> <span class="n">model</span><span class="o">.</span><span class="n">__module__</span> <span class="n">overrides</span><span class="p">[</span><span class="s2">"_deferred"</span><span class="p">]</span> <span class="o">=</span> <span class="kc">True</span> <span class="k">return</span> <span class="nb">type</span><span class="p">(</span><span class="nb">str</span><span class="p">(</span><span class="n">name</span><span class="p">),</span> <span class="p">(</span><span class="n">model</span><span class="p">,),</span> <span class="n">overrides</span><span class="p">)</span> <span class="c1"># The above function is also used to unpickle model instances with deferred</span> <span class="c1"># fields.</span> <span class="n">deferred_class_factory</span><span class="o">.</span><span class="n">__safe_for_unpickling__</span> <span class="o">=</span> <span class="kc">True</span> <span class="k">def</span> <span class="nf">refs_aggregate</span><span class="p">(</span><span class="n">lookup_parts</span><span class="p">,</span> <span class="n">aggregates</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> A little helper method to check if the lookup_parts contains references</span> <span class="sd"> to the given aggregates set. Because the LOOKUP_SEP is contained in the</span> <span class="sd"> default annotation names we must check each prefix of the lookup_parts</span> <span class="sd"> for a match.</span> <span class="sd"> """</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="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">level_n_lookup</span> <span class="ow">in</span> <span class="n">aggregates</span> <span class="ow">and</span> <span class="n">aggregates</span><span class="p">[</span><span class="n">level_n_lookup</span><span class="p">]</span><span class="o">.</span><span class="n">contains_aggregate</span><span class="p">:</span> <span class="k">return</span> <span class="n">aggregates</span><span class="p">[</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">False</span><span class="p">,</span> <span class="p">()</span> <span class="k">def</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="sd">"""</span> <span class="sd"> A helper method to check if the lookup_parts contains references</span> <span class="sd"> to the given annotations set. Because the LOOKUP_SEP is contained in the</span> <span class="sd"> default annotation names we must check each prefix of the lookup_parts</span> <span class="sd"> for a match.</span> <span class="sd"> """</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="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">level_n_lookup</span> <span class="ow">in</span> <span class="n">annotations</span> <span class="ow">and</span> <span class="n">annotations</span><span class="p">[</span><span class="n">level_n_lookup</span><span class="p">]:</span> <span class="k">return</span> <span class="n">annotations</span><span class="p">[</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">False</span><span class="p">,</span> <span class="p">()</span> </pre></div> </div> </div> </div> <div class="yui-b" id="sidebar"> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h3>Browse</h3> <ul> </ul> <h3>You are here:</h3> <ul> <li> <a href="../../../../index.html">Django 1.8.19 documentation</a> <ul><li><a href="../../../index.html">Module code</a> <ul><li><a href="../../../django.html">django</a> <ul><li>django.db.models.query_utils</li></ul> </li></ul></li></ul> </li> </ul> <div id="searchbox" style="display: none" role="search"> <h3>Quick search</h3> <form class="search" action="../../../../search.html" method="get"> <div><input type="text" name="q" /></div> <div><input type="submit" value="Go" /></div> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <h3>Last update:</h3> <p class="topless">Mar 10, 2018</p> </div> </div> <div id="ft"> <div class="nav"> <a href="../../../index.html" title="Module code" accesskey="U">up</a></div> </div> </div> <div class="clearer"></div> </div> </body> </html>