Apply validation before Data Transform

问题:

I want to transform a text field that I got from submitted user data to an Object in Symfony2. I used DataTransformer in order to do this. When I use built-in validators like 'NotEmpty' or 'NotNull' or any custom validators that built in standard way Symfony2 passes my specific object to them but I want to validate this text field before converting it to object. What should I do? (sry if my English is not so good)

回答1:

Validation are always done on the reverse transformed data.

The best way to add validation rule before the transformation occurred is to use an event listener or subscriber on FormEvents::PRE_SUBMIT.

You'll get the raw data. Just apply your validation logic here then use the $event->getForm()->get('xxxx')->addError() method to add errors on the corresponding field.

More informations on event subscribers / listeners :

http://symfony.com/doc/current/components/form/form_events.html#event-listeners http://symfony.com/doc/current/components/form/form_events.html#event-subscribers