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<h1>Source code for django.db.models.indexes</h1><div class="highlight"><pre>
<span></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">import</span> <span class="nn">hashlib</span>
<span class="kn">from</span> <span class="nn">django.db.backends.utils</span> <span class="k">import</span> <span class="n">split_identifier</span>
<span class="kn">from</span> <span class="nn">django.utils.encoding</span> <span class="k">import</span> <span class="n">force_bytes</span>
<span class="n">__all__</span> <span class="o">=</span> <span class="p">[</span><span class="nb">str</span><span class="p">(</span><span class="s1">'Index'</span><span class="p">)]</span>
<div class="viewcode-block" id="Index"><a class="viewcode-back" href="../../../../ref/models/indexes.html#django.db.models.Index">[docs]</a><span class="k">class</span> <span class="nc">Index</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="n">suffix</span> <span class="o">=</span> <span class="s1">'idx'</span>
<span class="c1"># The max length of the name of the index (restricted to 30 for</span>
<span class="c1"># cross-database compatibility with Oracle)</span>
<span class="n">max_name_length</span> <span class="o">=</span> <span class="mi">30</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">fields</span><span class="o">=</span><span class="p">[],</span> <span class="n">name</span><span class="o">=</span><span class="kc">None</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">fields</span><span class="p">,</span> <span class="nb">list</span><span class="p">):</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">'Index.fields must be a list.'</span><span class="p">)</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">fields</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">'At least one field is required to define an index.'</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">fields</span> <span class="o">=</span> <span class="n">fields</span>
<span class="c1"># A list of 2-tuple with the field name and ordering ('' or 'DESC').</span>
<span class="bp">self</span><span class="o">.</span><span class="n">fields_orders</span> <span class="o">=</span> <span class="p">[</span>
<span class="p">(</span><span class="n">field_name</span><span class="p">[</span><span class="mi">1</span><span class="p">:],</span> <span class="s1">'DESC'</span><span class="p">)</span> <span class="k">if</span> <span class="n">field_name</span><span class="o">.</span><span class="n">startswith</span><span class="p">(</span><span class="s1">'-'</span><span class="p">)</span> <span class="k">else</span> <span class="p">(</span><span class="n">field_name</span><span class="p">,</span> <span class="s1">''</span><span class="p">)</span>
<span class="k">for</span> <span class="n">field_name</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">fields</span>
<span class="p">]</span>
<span class="bp">self</span><span class="o">.</span><span class="n">name</span> <span class="o">=</span> <span class="n">name</span> <span class="ow">or</span> <span class="s1">''</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span><span class="p">:</span>
<span class="n">errors</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">check_name</span><span class="p">()</span>
<span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">name</span><span class="p">)</span> <span class="o">></span> <span class="bp">self</span><span class="o">.</span><span class="n">max_name_length</span><span class="p">:</span>
<span class="n">errors</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="s1">'Index names cannot be longer than </span><span class="si">%s</span><span class="s1"> characters.'</span> <span class="o">%</span> <span class="bp">self</span><span class="o">.</span><span class="n">max_name_length</span><span class="p">)</span>
<span class="k">if</span> <span class="n">errors</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="n">errors</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">check_name</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">errors</span> <span class="o">=</span> <span class="p">[]</span>
<span class="c1"># Name can't start with an underscore on Oracle; prepend D if needed.</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="o">==</span> <span class="s1">'_'</span><span class="p">:</span>
<span class="n">errors</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="s1">'Index names cannot start with an underscore (_).'</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="s1">'D</span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span><span class="p">[</span><span class="mi">1</span><span class="p">:]</span>
<span class="c1"># Name can't start with a number on Oracle; prepend D if needed.</span>
<span class="k">elif</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">isdigit</span><span class="p">():</span>
<span class="n">errors</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="s1">'Index names cannot start with a number (0-9).'</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="s1">'D</span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span><span class="p">[</span><span class="mi">1</span><span class="p">:]</span>
<span class="k">return</span> <span class="n">errors</span>
<span class="k">def</span> <span class="nf">get_sql_create_template_values</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">model</span><span class="p">,</span> <span class="n">schema_editor</span><span class="p">,</span> <span class="n">using</span><span class="p">):</span>
<span class="n">fields</span> <span class="o">=</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">get_field</span><span class="p">(</span><span class="n">field_name</span><span class="p">)</span> <span class="k">for</span> <span class="n">field_name</span><span class="p">,</span> <span class="n">order</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">fields_orders</span><span class="p">]</span>
<span class="n">tablespace_sql</span> <span class="o">=</span> <span class="n">schema_editor</span><span class="o">.</span><span class="n">_get_index_tablespace_sql</span><span class="p">(</span><span class="n">model</span><span class="p">,</span> <span class="n">fields</span><span class="p">)</span>
<span class="n">quote_name</span> <span class="o">=</span> <span class="n">schema_editor</span><span class="o">.</span><span class="n">quote_name</span>
<span class="n">columns</span> <span class="o">=</span> <span class="p">[</span>
<span class="p">(</span><span class="s1">'</span><span class="si">%s</span><span class="s1"> </span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span><span class="n">quote_name</span><span class="p">(</span><span class="n">field</span><span class="o">.</span><span class="n">column</span><span class="p">),</span> <span class="n">order</span><span class="p">))</span><span class="o">.</span><span class="n">strip</span><span class="p">()</span>
<span class="k">for</span> <span class="n">field</span><span class="p">,</span> <span class="p">(</span><span class="n">field_name</span><span class="p">,</span> <span class="n">order</span><span class="p">)</span> <span class="ow">in</span> <span class="nb">zip</span><span class="p">(</span><span class="n">fields</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">fields_orders</span><span class="p">)</span>
<span class="p">]</span>
<span class="k">return</span> <span class="p">{</span>
<span class="s1">'table'</span><span class="p">:</span> <span class="n">quote_name</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">db_table</span><span class="p">),</span>
<span class="s1">'name'</span><span class="p">:</span> <span class="n">quote_name</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">name</span><span class="p">),</span>
<span class="s1">'columns'</span><span class="p">:</span> <span class="s1">', '</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">columns</span><span class="p">),</span>
<span class="s1">'using'</span><span class="p">:</span> <span class="n">using</span><span class="p">,</span>
<span class="s1">'extra'</span><span class="p">:</span> <span class="n">tablespace_sql</span><span class="p">,</span>
<span class="p">}</span>
<span class="k">def</span> <span class="nf">create_sql</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">model</span><span class="p">,</span> <span class="n">schema_editor</span><span class="p">,</span> <span class="n">using</span><span class="o">=</span><span class="s1">''</span><span class="p">):</span>
<span class="n">sql_create_index</span> <span class="o">=</span> <span class="n">schema_editor</span><span class="o">.</span><span class="n">sql_create_index</span>
<span class="n">sql_parameters</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_sql_create_template_values</span><span class="p">(</span><span class="n">model</span><span class="p">,</span> <span class="n">schema_editor</span><span class="p">,</span> <span class="n">using</span><span class="p">)</span>
<span class="k">return</span> <span class="n">sql_create_index</span> <span class="o">%</span> <span class="n">sql_parameters</span>
<span class="k">def</span> <span class="nf">remove_sql</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">model</span><span class="p">,</span> <span class="n">schema_editor</span><span class="p">):</span>
<span class="n">quote_name</span> <span class="o">=</span> <span class="n">schema_editor</span><span class="o">.</span><span class="n">quote_name</span>
<span class="k">return</span> <span class="n">schema_editor</span><span class="o">.</span><span class="n">sql_delete_index</span> <span class="o">%</span> <span class="p">{</span>
<span class="s1">'table'</span><span class="p">:</span> <span class="n">quote_name</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">db_table</span><span class="p">),</span>
<span class="s1">'name'</span><span class="p">:</span> <span class="n">quote_name</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">name</span><span class="p">),</span>
<span class="p">}</span>
<span class="k">def</span> <span class="nf">deconstruct</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">path</span> <span class="o">=</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="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="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="s1">'django.db.models.indexes'</span><span class="p">,</span> <span class="s1">'django.db.models'</span><span class="p">)</span>
<span class="k">return</span> <span class="p">(</span><span class="n">path</span><span class="p">,</span> <span class="p">(),</span> <span class="p">{</span><span class="s1">'fields'</span><span class="p">:</span> <span class="bp">self</span><span class="o">.</span><span class="n">fields</span><span class="p">,</span> <span class="s1">'name'</span><span class="p">:</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span><span class="p">})</span>
<span class="k">def</span> <span class="nf">clone</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""Create a copy of this Index."""</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="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="vm">__class__</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="nd">@staticmethod</span>
<span class="k">def</span> <span class="nf">_hash_generator</span><span class="p">(</span><span class="o">*</span><span class="n">args</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Generate a 32-bit digest of a set of arguments that can be used to</span>
<span class="sd"> shorten identifying names.</span>
<span class="sd"> """</span>
<span class="n">h</span> <span class="o">=</span> <span class="n">hashlib</span><span class="o">.</span><span class="n">md5</span><span class="p">()</span>
<span class="k">for</span> <span class="n">arg</span> <span class="ow">in</span> <span class="n">args</span><span class="p">:</span>
<span class="n">h</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">force_bytes</span><span class="p">(</span><span class="n">arg</span><span class="p">))</span>
<span class="k">return</span> <span class="n">h</span><span class="o">.</span><span class="n">hexdigest</span><span class="p">()[:</span><span class="mi">6</span><span class="p">]</span>
<span class="k">def</span> <span class="nf">set_name_with_model</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">model</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Generate a unique name for the index.</span>
<span class="sd"> The name is divided into 3 parts - table name (12 chars), field name</span>
<span class="sd"> (8 chars) and unique hash + suffix (10 chars). Each part is made to</span>
<span class="sd"> fit its size by truncating the excess length.</span>
<span class="sd"> """</span>
<span class="n">_</span><span class="p">,</span> <span class="n">table_name</span> <span class="o">=</span> <span class="n">split_identifier</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">db_table</span><span class="p">)</span>
<span class="n">column_names</span> <span class="o">=</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">get_field</span><span class="p">(</span><span class="n">field_name</span><span class="p">)</span><span class="o">.</span><span class="n">column</span> <span class="k">for</span> <span class="n">field_name</span><span class="p">,</span> <span class="n">order</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">fields_orders</span><span class="p">]</span>
<span class="n">column_names_with_order</span> <span class="o">=</span> <span class="p">[</span>
<span class="p">((</span><span class="s1">'-</span><span class="si">%s</span><span class="s1">'</span> <span class="k">if</span> <span class="n">order</span> <span class="k">else</span> <span class="s1">'</span><span class="si">%s</span><span class="s1">'</span><span class="p">)</span> <span class="o">%</span> <span class="n">column_name</span><span class="p">)</span>
<span class="k">for</span> <span class="n">column_name</span><span class="p">,</span> <span class="p">(</span><span class="n">field_name</span><span class="p">,</span> <span class="n">order</span><span class="p">)</span> <span class="ow">in</span> <span class="nb">zip</span><span class="p">(</span><span class="n">column_names</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">fields_orders</span><span class="p">)</span>
<span class="p">]</span>
<span class="c1"># The length of the parts of the name is based on the default max</span>
<span class="c1"># length of 30 characters.</span>
<span class="n">hash_data</span> <span class="o">=</span> <span class="p">[</span><span class="n">table_name</span><span class="p">]</span> <span class="o">+</span> <span class="n">column_names_with_order</span> <span class="o">+</span> <span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">suffix</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="s1">'</span><span class="si">%s</span><span class="s1">_</span><span class="si">%s</span><span class="s1">_</span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span>
<span class="n">table_name</span><span class="p">[:</span><span class="mi">11</span><span class="p">],</span>
<span class="n">column_names</span><span class="p">[</span><span class="mi">0</span><span class="p">][:</span><span class="mi">7</span><span class="p">],</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">_hash_generator</span><span class="p">(</span><span class="o">*</span><span class="n">hash_data</span><span class="p">),</span> <span class="bp">self</span><span class="o">.</span><span class="n">suffix</span><span class="p">),</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">name</span><span class="p">)</span> <span class="o"><=</span> <span class="bp">self</span><span class="o">.</span><span class="n">max_name_length</span><span class="p">,</span> <span class="p">(</span>
<span class="s1">'Index too long for multiple database support. Is self.suffix '</span>
<span class="s1">'longer than 3 characters?'</span>
<span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">check_name</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">%s</span><span class="s2">: fields='</span><span class="si">%s</span><span class="s2">'>"</span> <span class="o">%</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="vm">__class__</span><span class="o">.</span><span class="vm">__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="bp">self</span><span class="o">.</span><span class="n">fields</span><span class="p">))</span>
<span class="k">def</span> <span class="nf">__eq__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">other</span><span class="p">):</span>
<span class="k">return</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="vm">__class__</span> <span class="o">==</span> <span class="n">other</span><span class="o">.</span><span class="vm">__class__</span><span class="p">)</span> <span class="ow">and</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">deconstruct</span><span class="p">()</span> <span class="o">==</span> <span class="n">other</span><span class="o">.</span><span class="n">deconstruct</span><span class="p">())</span>
<span class="k">def</span> <span class="nf">__ne__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">other</span><span class="p">):</span>
<span class="k">return</span> <span class="ow">not</span> <span class="p">(</span><span class="bp">self</span> <span class="o">==</span> <span class="n">other</span><span class="p">)</span></div>
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