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<h1>SQLAlchemy 0.9 Documentation</h1>
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<h1>Source code for examples.generic_associations.table_per_related</h1><div class="highlight"><pre>
<span class="sd">"""table_per_related.py</span>
<span class="sd">Illustrates a generic association which persists association</span>
<span class="sd">objects within individual tables, each one generated to persist</span>
<span class="sd">those objects on behalf of a particular parent class.</span>
<span class="sd">This configuration has the advantage that each type of parent</span>
<span class="sd">maintains its "Address" rows separately, so that collection</span>
<span class="sd">size for one type of parent will have no impact on other types</span>
<span class="sd">of parent. Navigation between parent and "Address" is simple,</span>
<span class="sd">direct, and bidirectional.</span>
<span class="sd">This recipe is the most efficient (speed wise and storage wise)</span>
<span class="sd">and simple of all of them.</span>
<span class="sd">The creation of many related tables may seem at first like an issue</span>
<span class="sd">but there really isn't any - the management and targeting of these tables</span>
<span class="sd">is completely automated.</span>
<span class="sd">"""</span>
<span class="kn">from</span> <span class="nn">sqlalchemy.ext.declarative</span> <span class="kn">import</span> <span class="n">as_declarative</span><span class="p">,</span> <span class="n">declared_attr</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="kn">import</span> <span class="n">create_engine</span><span class="p">,</span> <span class="n">Integer</span><span class="p">,</span> <span class="n">Column</span><span class="p">,</span> <span class="n">String</span><span class="p">,</span> <span class="n">ForeignKey</span>
<span class="kn">from</span> <span class="nn">sqlalchemy.orm</span> <span class="kn">import</span> <span class="n">Session</span><span class="p">,</span> <span class="n">relationship</span>
<span class="nd">@as_declarative</span><span class="p">()</span>
<span class="k">class</span> <span class="nc">Base</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="sd">"""Base class which provides automated table name</span>
<span class="sd"> and surrogate primary key column.</span>
<span class="sd"> """</span>
<span class="nd">@declared_attr</span>
<span class="k">def</span> <span class="nf">__tablename__</span><span class="p">(</span><span class="n">cls</span><span class="p">):</span>
<span class="k">return</span> <span class="n">cls</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="nb">id</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">Integer</span><span class="p">,</span> <span class="n">primary_key</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">Address</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="sd">"""Define columns that will be present in each</span>
<span class="sd"> 'Address' table.</span>
<span class="sd"> This is a declarative mixin, so additional mapped</span>
<span class="sd"> attributes beyond simple columns specified here</span>
<span class="sd"> should be set up using @declared_attr.</span>
<span class="sd"> """</span>
<span class="n">street</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">String</span><span class="p">)</span>
<span class="n">city</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">String</span><span class="p">)</span>
<span class="nb">zip</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">String</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="s">"</span><span class="si">%s</span><span class="s">(street=</span><span class="si">%r</span><span class="s">, city=</span><span class="si">%r</span><span class="s">, zip=</span><span class="si">%r</span><span class="s">)"</span> <span class="o">%</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">street</span><span class="p">,</span>
<span class="bp">self</span><span class="o">.</span><span class="n">city</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">zip</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">HasAddresses</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="sd">"""HasAddresses mixin, creates a new Address class</span>
<span class="sd"> for each parent.</span>
<span class="sd"> """</span>
<span class="nd">@declared_attr</span>
<span class="k">def</span> <span class="nf">addresses</span><span class="p">(</span><span class="n">cls</span><span class="p">):</span>
<span class="n">cls</span><span class="o">.</span><span class="n">Address</span> <span class="o">=</span> <span class="nb">type</span><span class="p">(</span>
<span class="s">"</span><span class="si">%s</span><span class="s">Address"</span> <span class="o">%</span> <span class="n">cls</span><span class="o">.</span><span class="n">__name__</span><span class="p">,</span>
<span class="p">(</span><span class="n">Address</span><span class="p">,</span> <span class="n">Base</span><span class="p">,),</span>
<span class="nb">dict</span><span class="p">(</span>
<span class="n">__tablename__</span><span class="o">=</span><span class="s">"</span><span class="si">%s</span><span class="s">_address"</span> <span class="o">%</span>
<span class="n">cls</span><span class="o">.</span><span class="n">__tablename__</span><span class="p">,</span>
<span class="n">parent_id</span><span class="o">=</span><span class="n">Column</span><span class="p">(</span><span class="n">Integer</span><span class="p">,</span>
<span class="n">ForeignKey</span><span class="p">(</span><span class="s">"</span><span class="si">%s</span><span class="s">.id"</span> <span class="o">%</span> <span class="n">cls</span><span class="o">.</span><span class="n">__tablename__</span><span class="p">)),</span>
<span class="n">parent</span><span class="o">=</span><span class="n">relationship</span><span class="p">(</span><span class="n">cls</span><span class="p">)</span>
<span class="p">)</span>
<span class="p">)</span>
<span class="k">return</span> <span class="n">relationship</span><span class="p">(</span><span class="n">cls</span><span class="o">.</span><span class="n">Address</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">Customer</span><span class="p">(</span><span class="n">HasAddresses</span><span class="p">,</span> <span class="n">Base</span><span class="p">):</span>
<span class="n">name</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">String</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">Supplier</span><span class="p">(</span><span class="n">HasAddresses</span><span class="p">,</span> <span class="n">Base</span><span class="p">):</span>
<span class="n">company_name</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">String</span><span class="p">)</span>
<span class="n">engine</span> <span class="o">=</span> <span class="n">create_engine</span><span class="p">(</span><span class="s">'sqlite://'</span><span class="p">,</span> <span class="n">echo</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
<span class="n">Base</span><span class="o">.</span><span class="n">metadata</span><span class="o">.</span><span class="n">create_all</span><span class="p">(</span><span class="n">engine</span><span class="p">)</span>
<span class="n">session</span> <span class="o">=</span> <span class="n">Session</span><span class="p">(</span><span class="n">engine</span><span class="p">)</span>
<span class="n">session</span><span class="o">.</span><span class="n">add_all</span><span class="p">([</span>
<span class="n">Customer</span><span class="p">(</span>
<span class="n">name</span><span class="o">=</span><span class="s">'customer 1'</span><span class="p">,</span>
<span class="n">addresses</span><span class="o">=</span><span class="p">[</span>
<span class="n">Customer</span><span class="o">.</span><span class="n">Address</span><span class="p">(</span>
<span class="n">street</span><span class="o">=</span><span class="s">'123 anywhere street'</span><span class="p">,</span>
<span class="n">city</span><span class="o">=</span><span class="s">"New York"</span><span class="p">,</span>
<span class="nb">zip</span><span class="o">=</span><span class="s">"10110"</span><span class="p">),</span>
<span class="n">Customer</span><span class="o">.</span><span class="n">Address</span><span class="p">(</span>
<span class="n">street</span><span class="o">=</span><span class="s">'40 main street'</span><span class="p">,</span>
<span class="n">city</span><span class="o">=</span><span class="s">"San Francisco"</span><span class="p">,</span>
<span class="nb">zip</span><span class="o">=</span><span class="s">"95732"</span><span class="p">)</span>
<span class="p">]</span>
<span class="p">),</span>
<span class="n">Supplier</span><span class="p">(</span>
<span class="n">company_name</span><span class="o">=</span><span class="s">"Ace Hammers"</span><span class="p">,</span>
<span class="n">addresses</span><span class="o">=</span><span class="p">[</span>
<span class="n">Supplier</span><span class="o">.</span><span class="n">Address</span><span class="p">(</span>
<span class="n">street</span><span class="o">=</span><span class="s">'2569 west elm'</span><span class="p">,</span>
<span class="n">city</span><span class="o">=</span><span class="s">"Detroit"</span><span class="p">,</span>
<span class="nb">zip</span><span class="o">=</span><span class="s">"56785"</span><span class="p">)</span>
<span class="p">]</span>
<span class="p">),</span>
<span class="p">])</span>
<span class="n">session</span><span class="o">.</span><span class="n">commit</span><span class="p">()</span>
<span class="k">for</span> <span class="n">customer</span> <span class="ow">in</span> <span class="n">session</span><span class="o">.</span><span class="n">query</span><span class="p">(</span><span class="n">Customer</span><span class="p">):</span>
<span class="k">for</span> <span class="n">address</span> <span class="ow">in</span> <span class="n">customer</span><span class="o">.</span><span class="n">addresses</span><span class="p">:</span>
<span class="k">print</span><span class="p">(</span><span class="n">address</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="n">address</span><span class="o">.</span><span class="n">parent</span><span class="p">)</span></pre></div>
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