Update Callback.rst

berny46 · berny46 · commit a2ec22b2a83f · 2013-12-03T15:51:17.000+01:00
add square brackets to yaml codeblock (constraints: - Callback: [validate]). Otherwise an error "Expected argument of type array, string given" is thrown
diff --git a/reference/constraints/Callback.rst b/reference/constraints/Callback.rst
@@ -42,7 +42,7 @@ Configuration
         # src/Acme/BlogBundle/Resources/config/validation.yml
         Acme\BlogBundle\Entity\Author:
             constraints:
-                - Callback: validate
+                - Callback: [validate]
 
     .. code-block:: php-annotations
 
