title: Symfony2 generate form for entity of another entity (location of a shop)
body: <p>i'm trying to figure this out for a while now.</p>
  
  <p>I can't find any documentation on how to do the following:</p>
  
  <p>I have 2 entities Shop and Location, a shop can have more locations
  The entities are already working correctly in the database.</p>
  
  <p>But now i want to make a form to add a location to a shop.
  If i render the form with ->add('shop', 'entity') in the LocationType then i will get a dropdown.</p>
  
  <p>What i want is a hidden (not changable) field with the shop id.</p>
  
  <p>Any suggestions?</p>
  
  <p>Here is my code for the LocationType: ([STORENAME] is the replacement of the name of the company)</p>
  
  <pre><code>class LocationType extends AbstractType
  {
      public function buildForm(FormBuilderInterface $builder, array $options)
      {
          $builder
              -&gt;add('name', 'text')
              -&gt;add('street')
              -&gt;add('number')
              -&gt;add('numberAddition')
              -&gt;add('postalcode')
              -&gt;add('city')
              -&gt;add('phone')
              -&gt;add('email')
              -&gt;add('shop', 'entity', array(
                  'class' =&gt; '[STORENAME]ShopBundle:Shop',
                  'property' =&gt; 'name'))
          ;
      }
  </code></pre>
  
  <p>Txs!,
  Greetings</p>