<p>Hi Sirs,</p> <p>Many tutorials over the web shows how to load data from fixtures. But, if you want to migrate your <em>mysql</em> data to a <em>postgresql</em> database?</p> <p>We can export our data to fixtures, and after that we can load the fixtures to every database management system we wish.</p> <p>Let's go to the rake task:</p> <pre><span class="ident">desc</span> <span class="punct">&quot;</span><span class="string">export the database models to YML fixtures</span><span class="punct">&quot;</span> <span class="ident">task</span><span class="punct">(</span><span class="symbol">:models_to_fixtures</span> <span class="punct">=&gt;</span> <span class="symbol">:environment</span><span class="punct">)</span> <span class="keyword">do</span> <span class="constant">ActiveRecord</span><span class="punct">::</span><span class="constant">Base</span><span class="punct">.</span><span class="ident">establish_connection</span><span class="punct">(</span> <span class="symbol">:adapter</span> <span class="punct">=&gt;</span> <span class="punct">'</span><span class="string">postgresql</span><span class="punct">',</span> <span class="comment"># mysql, sqlite3</span> <span class="symbol">:encoding</span> <span class="punct">=&gt;</span> <span class="punct">'</span><span class="string">utf8</span><span class="punct">',</span> <span class="symbol">:database</span> <span class="punct">=&gt;</span> <span class="punct">'</span><span class="string">cnxs_development</span><span class="punct">',</span> <span class="symbol">:username</span> <span class="punct">=&gt;</span> <span class="punct">'</span><span class="string">username</span><span class="punct">',</span> <span class="symbol">:password</span> <span class="punct">=&gt;</span> <span class="punct">'</span><span class="string">secret</span><span class="punct">'</span> <span class="punct">)</span> <span class="constant">ActiveRecord</span><span class="punct">::</span><span class="constant">Base</span><span class="punct">.</span><span class="ident">connection</span> <span class="keyword">if</span> <span class="constant">ENV</span><span class="punct">['</span><span class="string">MODELS</span><span class="punct">'].</span><span class="ident">nil?</span> <span class="punct">||</span> <span class="constant">ENV</span><span class="punct">['</span><span class="string">MODELS</span><span class="punct">'].</span><span class="ident">blank?</span> <span class="keyword">raise</span> <span class="punct">&quot;</span><span class="string">Please enter valid models names separated by coma. Ex: MODELS=User,Account</span><span class="punct">&quot;</span> <span class="keyword">end</span> <span class="ident">models</span> <span class="punct">=</span> <span class="constant">ENV</span><span class="punct">['</span><span class="string">MODELS</span><span class="punct">'].</span><span class="ident">split</span><span class="punct">('</span><span class="string">,</span><span class="punct">').</span><span class="ident">collect</span> <span class="punct">{</span> <span class="punct">|</span><span class="ident">arg</span><span class="punct">|</span> <span class="ident">arg</span><span class="punct">.</span><span class="ident">camelize</span><span class="punct">.</span><span class="ident">constantize</span> <span class="punct">}</span> <span class="ident">models</span><span class="punct">.</span><span class="ident">each</span> <span class="keyword">do</span> <span class="punct">|</span><span class="ident">model</span><span class="punct">|</span> <span class="ident">output</span> <span class="punct">=</span> <span class="punct">{}</span> <span class="ident">collection</span> <span class="punct">=</span> <span class="ident">model</span><span class="punct">.</span><span class="ident">find</span><span class="punct">(</span><span class="symbol">:all</span><span class="punct">)</span> <span class="ident">collection</span><span class="punct">.</span><span class="ident">each</span> <span class="keyword">do</span> <span class="punct">|</span><span class="ident">object</span><span class="punct">|</span> <span class="ident">output</span><span class="punct">.</span><span class="ident">store</span><span class="punct">(</span><span class="ident">object</span><span class="punct">.</span><span class="ident">to_param</span><span class="punct">,</span> <span class="ident">object</span><span class="punct">.</span><span class="ident">attributes</span><span class="punct">)</span> <span class="keyword">end</span> <span class="ident">file_path</span> <span class="punct">=</span> <span class="punct">&quot;</span><span class="string"><span class="expr">#{RAILS_ROOT}</span>/tmp/<span class="expr">#{model.table_name}</span>.yml</span><span class="punct">&quot;</span> <span class="comment"># /tmp/</span> <span class="constant">File</span><span class="punct">.</span><span class="ident">open</span><span class="punct">(</span><span class="ident">file_path</span><span class="punct">,</span> <span class="punct">&quot;</span><span class="string">w+</span><span class="punct">&quot;)</span> <span class="punct">{</span> <span class="punct">|</span><span class="ident">file</span><span class="punct">|</span> <span class="ident">file</span><span class="punct">.</span><span class="ident">write</span><span class="punct">(</span><span class="ident">output</span><span class="punct">.</span><span class="ident">to_yaml</span><span class="punct">)</span> <span class="punct">}</span> <span class="keyword">end</span> <span class="keyword">end</span> </pre> <p>Here you need to fill your database attributes like you do in the <em>/config/database.yml</em>.</p> <p>You will call the command line:</p> <pre><code>$ rake models_to_fixtures MODELS=&lt;your model names separated by coma&gt;</code></pre> <p>For example:</p><pre><code>$ rake models_to_fixtures MODELS=User,Post</code></pre><p>All your model data will be stored on <em>/tmp/</em> directory.</p> <p>Download this rake task <a href="../../models_to_fixtures.rake">here</a>.</p> <p>See you.</p> 2008-07-08T17:12:49Z 27 export-the-database-models-to-yml-fixtures 2008-11-13T19:54:17Z 3