feature #3124 Add note about the property attribute (Property Accesso…

…r) (raziel057)

This PR was submitted for the 2.2 branch but it was merged into the 2.3 branch instead (closes #3124).

Discussion
----------

Add note about the property attribute (Property Accessor)

I think we must document the fact that propety is a path which is evaluted by the PropertyAccessor component.

Commits
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46f1b8b Update entity.rst
7496e68 Update entity.rst
c097f9b Update entity.rst
7d65fed Update entity.rst
6af779d Add note about the property attribute (Property Accessor)

reference/forms/types/entity.rst

@@ -118,6 +118,20 @@ This is the property that should be used for displaying the entities
 as text in the HTML element. If left blank, the entity object will be
 cast into a string and so must have a ``__toString()`` method.
 
+.. note::
+
+    The ``property`` option is the property path used to display the option. So you 
+    can use anything supported by the
+    :doc:`PropertyAccessor component </components/property_access/introduction>`
+
+    For example, if the translations property is actually an associative array of 
+    objects, each with a name property, then you could do this::
+
+        $builder->add('gender', 'entity', array(
+           'class' => 'MyBundle:Gender',
+           'property' => 'translations[en].name',
+        ));
+
 group_by
 ~~~~~~~~