Templates

For information on overriding templates, see

• How to Override Templates from Third-Party Bundles.
• How to Use Bundle Inheritance to Override Parts of a Bundle

Routing

Routing is never automatically imported in Symfony. If you want to include the routes from any bundle, then they must be manually imported from somewhere in your application (e.g. app/config/routing.yml).

The easiest way to "override" a bundle's routing is to never import it at all. Instead of importing a third-party bundle's routing, simply copy that routing file into your application, modify it, and import it instead.

Controllers

Assuming the third-party bundle involved uses non-service controllers (which is almost always the case), you can easily override controllers via bundle inheritance. For more information, see How to Use Bundle Inheritance to Override Parts of a Bundle. If the controller is a service, see the next section on how to override it.

Services & Configuration

If you want to modify service definitions of another bundle, you can use a compiler pass to change the class of the service or to modify method calls. In the following example, the implementing class for the original-service-id is changed to
Acme\DemoBundle\YourService:

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// src/Acme/DemoBundle/DependencyInjection/Compiler/OverrideServiceCompilerPass.php
namespace Acme\DemoBundle\DependencyInjection\Compiler;

use Acme\DemoBundle\YourService;
use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\ContainerBuilder;

class OverrideServiceCompilerPass implements CompilerPassInterface
{
    public function process(ContainerBuilder $container)
    {
        $definition = $container->getDefinition('original-service-id');
        $definition->setClass(YourService::class);
    }
}

For more information on compiler passes, see How to Work with Compiler Passes in Bundles.

Entities & Entity Mapping

Due to the way Doctrine works, it is not possible to override entity mapping of a bundle. However, if a bundle provides a mapped superclass (such as the User entity in the FOSUserBundle) one can override attributes and associations. Learn more about this feature and its limitations in the Doctrine documentation.

Forms

Form types are referred to by their fully-qualified class name:

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$builder->add('name', CustomType::class);

This means that you cannot override this by creating a sub-class of CustomType and registering it as a service and tagging it with form.type (you could do this in earlier version).

Instead, you should use a "form type extension" to modify the existing form type. For more information, see How to Create a Form Type Extension.

Validation Metadata

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 them.

To override this, the 3rd party bundle needs to have configuration for validation groups. For instance, the FOSUserBundle has this configuration. To create your own validation, add the constraints to a new validation group:

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# 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]

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<!-- 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="plainPassword">
            <constraint name="NotBlank">
                <option name="groups">
                    <value>AcmeValidation</value>
                </option>
            </constraint>

            <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.

Translations

Translations are not related to bundles, but to domains. That means that you can override the translations from any translation file, as long as it is in the correct domain.