If your constraint validator has dependencies, such as a database connection,

it will need to be configured as a service in the Dependency Injection

Container. This service must include the ``validator.constraint_validator``

tagand should include an ``alias`` attribute to be used inthevalidatedBy method of your validator class:

tagso thatthevalidation system knows about it::

..configuration-block::

..code-block::yaml

..code-block::xml

..code-block::php

As mentioned above,Symfonywill automatically lookfora class named after

the constraint, with ``Validator`` appended. You can overridethisin your constraint class::

Now, whenSymfonylooksforthe ``ContainsAlphanumericValidator`` validator, it will

loadthisservice from the container.

Make sure to use the 'alias_name' when you have configured your validator as a service. Otherwise your validator class

will be simply instantiated without your dependencies.

..note::

In earlier versions of Symfony, the tag required an ``alias`` key (usually set

to the class name). This is still allowed your constraint's ``validateBy``

method can return this alias (instead of a class name).

Class Constraint Validator