Add option to add constraints to data types

[nobears]

I haven't been working with Pimcore for a long time but found the need to add validation to a text data type (input) a few times. Right now I do this by hooking on to the PRE_ADD and/or PRE_UPDATE events and throwing a ValidationException when things aren't right.

I was thinking maybe we can add an option to Pimcore where you can add one or more constraints to a data type in your class definition. This would consist simply of the FQCN of a constraint + the option to apply this on creation and/or saving. This way you can easily use Symfony's constraints or your own custom constraints.

What do you guys think? If you think it's a good idea; technically I'm thinking to still solve this with an event listener, but perhaps it's better to just check for constraints on the data object directly.

[dpfaffenbauer]

We usually add a event listener and run the Symfony Validator there. We configure symfony validations then for that object. I guess that is something Pimcore could do in core.