title: Symfony2, Propel fixtures and concrete inheritance
body: <p>I got an issue with Propel fixtures loading in Symfony2. I have the following schema:</p>
  
  <pre><code>&lt;table name="application" phpName="Application"&gt;
  
     &lt;column name="id" type="integer" required="true" primaryKey="true" autoIncrement="true" /&gt;
     &lt;column name="name" type="varchar" required="true" primaryString="true" /&gt;
  
     &lt;behavior name="timestampable" /&gt;
  
  &lt;/table&gt;
  
  &lt;table name="application_iphone" phpName="IphoneApplication"&gt;
  
     &lt;column name="store_id" type="varchar" required="true" /&gt;
  
     &lt;behavior name="concrete_inheritance"&gt;
         &lt;parameter name="extends" value="application" /&gt;
     &lt;/behavior&gt;
  
  &lt;/table&gt;
  
  &lt;table name="application_identifier" phpName="IphoneApplicationIdentifier"&gt;
  
      &lt;column name="id" type="integer" required="true" primaryKey="true" autoIncrement="true" /&gt;
      &lt;column name="application_id" required="true" type="integer" /&gt;
      &lt;column name="identifier" type="varchar" required="true" primaryString="true" /&gt;
  
      &lt;foreign-key foreignTable="application_iphone"&gt;
          &lt;reference local="application_id" foreign="id" /&gt;                                 
      &lt;/foreign-key&gt;     
  
  &lt;/table&gt;
  </code></pre>
  
  <p>The model builds correctly. The issue raises when I try to load the following fixtures:</p>
  
  <pre><code>Acme\MyBundle\Model\Application:
      first_app:
          name: "MyFirstApp"
          descendant_class: "IphoneApplication"
  
  Acme\MyBundle\Model\IphoneApplication:
      first_app_iphone:
          id: first_app
          store_id: 2342
  
  Acme\MyBundle\Model\IphoneApplicationIdentifier:     
      first_app_identifier:
          identifier: "com.acme.myfirstapp.appstore"
          application_id: first_app_iphone
  </code></pre>
  
  <p>The following error occurs:</p>
  
  <blockquote>
    <p>[Propel] Exception<br>
    Cannot insert a value for auto-increment primary key (application.ID)</p>
  </blockquote>
  
  <p>I added my "first_app" application twice (one in <em>Application</em>, another time in <em>IphoneApplication</em>) to prevent from another issue with my <em>IphoneApplicationIdentifier</em> fixture:</p>
  
  <blockquote>
    <p>[Propel] Exception The object "first_app" from class
    "Acme\MyBundle\Model\Application" is not defined in your data file.</p>
  </blockquote>
  
  <p>How can I insert fixtures for a concrete inheritant model?</p>