Symfony2 validation in XML

I have made it through half of the Symfony2 bible and am now reading up on validation. My bundles uses XML configuration, so I switched to that format in the examples and used the following to constraint my Log entity.

<class name="Nogfx\LogBundle\Entity\Log">
    <property name="title">
        <constraint name="NotBlank" />
    </property>
</class>

Sadly it crashed with an error message:

[ERROR 1845] Element 'class': No matching global declaration available for the validation root. (in /app/dir/src/Nogfx/LogBundle/Resources/config/validation.xml - line 1, column 0)
 
500 Internal Server Error - MappingException

So the XML was obviously malformed. But how then should it be structured?

After some digging around I managed to find an example and that cleared it out. Given my previous example, this is how it should have been structured instead.

<?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/services/constraint-mapping-1.0.xsd">
 
    <class name="Nogfx\LogBundle\Entity\Log">
        <property name="title">
            <constraint name="NotBlank" />
        </property>
    </class>
 
<constraint-mapping>

Just like with the routing, we need to define a root element with a proper namespace and DTD. Adding that solved my problem.

This should of course be fixed in the documentation and I will do so myself if no one else beats me to it. Still, I hope this post can help someone with the same problem before the fix is in.

Update: Ryan Weaver accepted my pull request and this problem should be fixed on next deployment.