Added last missing override section

cookbook/bundles/inheritance.rst

@@ -73,8 +73,8 @@ original method, and change its functionality::
     the controller using the standard ``FOSUserBundle:Registration:register``
     syntax in routes and templates. This is the best practice.
 
-Overriding Resources: Templates, Routing, Validation, etc
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Overriding Resources: Templates, Routing, etc
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Most resources can also be overridden, simply by creating a file in the same
 location as your parent bundle.
@@ -86,7 +86,7 @@ you can create your own file in the same location of ``AcmeUserBundle``.
 Symfony will ignore the file that lives inside the ``FOSUserBundle`` entirely,
 and use your file instead.
 
-The same goes for routing files, validation configuration and other resources.
+The same goes for routing files and some other resources.
 
 .. note::
 
@@ -97,8 +97,9 @@ The same goes for routing files, validation configuration and other resources.
 
 .. caution::
 
-   Translation files do not work in the same way as described above. Read
-   :ref:`override-translations` if you want to learn how to override
-   translations.
+   Translation and validation files do not work in the same way as described
+   above. Read ":ref:`override-translations`" if you want to learn how to
+   override translations and see ":ref:`override-validation`" for tricks to
+   override the validation.
 
 .. _`FOSUserBundle`: https://github.com/friendsofsymfony/fosuserbundle

cookbook/bundles/override.rst

@@ -117,10 +117,58 @@ rather than::
 
     $builder->add('name', new CustomType());
 
+.. _override-validation:
+
 Validation metadata
 -------------------
 
-In progress...
+Symfony loads all validation configuration files from every bundle and
+combines them into one validation metadata tree. This means you are able to
+add new constraints to a property, but you cannot override it.
+
+To override this, the 3th party bundle needs to have configuration for
+:ref:`validation groups <book-validation-validation-groups>`. For instance,
+the FOSUserBundle has this configuration. To create your own validation, add
+the constraints to a new validation group:
+
+.. configuration-block::
+
+    .. code-block:: yaml
+
+        # src/Acme/UserBundle/Resources/config/validation.yml
+        Fos\UserBundle\Model\User:
+            properties:
+                plainPassword:
+                    - NotBlank:
+                        groups: [AcmeValidation]
+                    - Length:
+                        min: 6
+                        minMessage: fos_user.password.short
+                        groups: [AcmeValidation]
+
+    .. code-block:: xml
+
+        <!-- src/Acme/UserBundle/Resources/config/validation.xml -->
+        <?xml version="1.0" encoding="UTF-8" ?>
+        <constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping"
+            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+            xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping http://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">
+
+            <class name="Fos\UserBundle\Model\User">
+                <property name="password">
+                    <constraint name="Length">
+                        <option name="min">6</option>
+                        <option name="minMessage">fos_user.password.short</option>
+                        <option name="groups">
+                            <value>AcmeValidation</value>
+                        </option>
+                    </constraint>
+                </property>
+            </class>
+        </constraint-mapping>
+
+Now, update the FosUserBundle configuration, so it uses your validation groups
+instead of the original ones.
 
 .. _override-translations: