Symfony2 forms How to call validator before transformer?

Question

symfony

I have a field for entering a date (widget text) on the form.
I need to check it with a regular expression, then convert it to Datetime.
To check, I add a constraint of the Regex type in the form class, to convert - addModelTransformer or addViewTransformer. Well, Regex throws an error, since DateTime is passed to it instead of a string. I would not like to take out the transformation in the controller.

Answer 1

The fact is that validation is checked during the reverse transformation, therefore, transformation always takes place first, and only then - validation.
You must do validation not through the standard Constraints, write your own validation, and run it through an event using FormEvents::PRE_SUBMIT.
This answer has a little more information about it.