<!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"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title> examples.generic_associations.table_per_related — SQLAlchemy 1.2 Documentation </title> <!-- begin iterate through site-imported + sphinx environment css_files --> <link rel="stylesheet" href="../../../_static/pygments.css" type="text/css" /> <link rel="stylesheet" href="../../../_static/docs.css" type="text/css" /> <link rel="stylesheet" href="../../../_static/changelog.css" type="text/css" /> <link rel="stylesheet" href="../../../_static/sphinx_paramlinks.css" type="text/css" /> <!-- end iterate through site-imported + sphinx environment css_files --> <!-- begin layout.mako headers --> <link rel="index" title="Index" href="../../../genindex.html" /> <link rel="search" title="Search" href="../../../search.html" /> <link rel="copyright" title="Copyright" href="../../../copyright.html" /> <link rel="top" title="SQLAlchemy 1.2 Documentation" href="../../../index.html" /> <link rel="up" title="Module code" href="../../index.html" /> <!-- end layout.mako headers --> </head> <body> <div id="docs-container"> <div id="docs-top-navigation-container" class="body-background"> <div id="docs-header"> <div id="docs-version-header"> Release: <span class="version-num">1.2.19</span> | Release Date: April 15, 2019 </div> <h1>SQLAlchemy 1.2 Documentation</h1> </div> </div> <div id="docs-body-container"> <div id="fixed-sidebar" class=""> <div id="index-nav"> <form class="search" action="../../../search.html" method="get"> <label> Search terms: <input type="text" placeholder="search..." name="q" size="12" /> </label> <input type="submit" value="Search" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> <p> <a href="../../../contents.html">Contents</a> | <a href="../../../genindex.html">Index</a> </p> </div> </div> <div id="docs-body" class="" > <h1>Source code for examples.generic_associations.table_per_related</h1><div class="highlight"><pre> <span></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</span> <span class="k">import</span> <span class="n">Column</span> <span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">create_engine</span> <span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">ForeignKey</span> <span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">Integer</span> <span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">String</span> <span class="kn">from</span> <span class="nn">sqlalchemy.ext.declarative</span> <span class="k">import</span> <span class="n">as_declarative</span> <span class="kn">from</span> <span class="nn">sqlalchemy.ext.declarative</span> <span class="k">import</span> <span class="n">declared_attr</span> <span class="kn">from</span> <span class="nn">sqlalchemy.orm</span> <span class="k">import</span> <span class="n">relationship</span> <span class="kn">from</span> <span class="nn">sqlalchemy.orm</span> <span class="k">import</span> <span class="n">Session</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="bp">cls</span><span class="p">):</span> <span class="k">return</span> <span class="bp">cls</span><span class="o">.</span><span class="vm">__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="kc">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="s2">"</span><span class="si">%s</span><span class="s2">(street=</span><span class="si">%r</span><span class="s2">, city=</span><span class="si">%r</span><span class="s2">, zip=</span><span class="si">%r</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="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="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="bp">cls</span><span class="p">):</span> <span class="bp">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="s2">"</span><span class="si">%s</span><span class="s2">Address"</span> <span class="o">%</span> <span class="bp">cls</span><span class="o">.</span><span class="vm">__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="s2">"</span><span class="si">%s</span><span class="s2">_address"</span> <span class="o">%</span> <span class="bp">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="s2">"</span><span class="si">%s</span><span class="s2">.id"</span> <span class="o">%</span> <span class="bp">cls</span><span class="o">.</span><span class="n">__tablename__</span><span class="p">)</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="bp">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="bp">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="s2">"sqlite://"</span><span class="p">,</span> <span class="n">echo</span><span class="o">=</span><span class="kc">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="p">[</span> <span class="n">Customer</span><span class="p">(</span> <span class="n">name</span><span class="o">=</span><span class="s2">"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="s2">"123 anywhere street"</span><span class="p">,</span> <span class="n">city</span><span class="o">=</span><span class="s2">"New York"</span><span class="p">,</span> <span class="nb">zip</span><span class="o">=</span><span class="s2">"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="s2">"40 main street"</span><span class="p">,</span> <span class="n">city</span><span class="o">=</span><span class="s2">"San Francisco"</span><span class="p">,</span> <span class="nb">zip</span><span class="o">=</span><span class="s2">"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="s2">"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="s2">"2569 west elm"</span><span class="p">,</span> <span class="n">city</span><span class="o">=</span><span class="s2">"Detroit"</span><span class="p">,</span> <span class="nb">zip</span><span class="o">=</span><span class="s2">"56785"</span> <span class="p">)</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="nb">print</span><span class="p">(</span><span class="n">address</span><span class="p">)</span> <span class="nb">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> </div> </div> <div id="docs-bottom-navigation" class="docs-navigation-links"> <div id="docs-copyright"> © <a href="../../../copyright.html">Copyright</a> 2007-2019, the SQLAlchemy authors and contributors. Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 2.0.1. </div> </div> </div> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../../../', VERSION: '1.2.19', COLLAPSE_MODINDEX: false, FILE_SUFFIX: '.html' }; </script> <script type="text/javascript" id="documentation_options" data-url_root="../../../" src="../../../_static/documentation_options.js"></script> <!-- begin iterate through sphinx environment script_files --> <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> <script type="text/javascript" src="../../../_static/language_data.js"></script> <!-- end iterate through sphinx environment script_files --> <script type="text/javascript" src="../../../_static/detectmobile.js"></script> <script type="text/javascript" src="../../../_static/init.js"></script> </body> </html>