Clarified Default and ClassName groups

[wouterj]

This is still the most difficult part of the validation groups and we
don't put much attention on it. I've refactored it a bit after the
really great explaination of @webmozart.

For more information see: symfony/symfony#10287 (comment)

Q	A
Doc fix?	yes
New docs?	yes
Applies to	all
Fixed tickets	-

[wouterj]

btw, also fixed some grammar in the Group Sequence Provider section

[lyrixx]

Thank you very much for that.

[webmozart]

IMO this is the wrong order. All constraints belong to the "Default" group first and foremost. "User" is just an alias for the constraints in the "Default" group of the User class. That means, for example:

class User extends Person
{
    /**
     * @Assert\Valid
     * @Assert\Type("Acme\Address")
     */
    private $address;
}

• When I validate a User object in the "Default" group, all default constraints of both the User and the Address will be validated.
• When I validate it in the "User" group, only the default constraints of the User class (and superclasses) will be executed
• When I validate it in the "Address" group, only the default constraints of the Address class will be executed.
• When I validated it in the "Person" group, only the default constraints of the Person class (and superclasses) will be executed.

[webmozart]

Btw, you should use CamelCaps notation for group names.

[wouterj]

About your first comment: Thanks a lot for creating such a nice real world examples! :) It helps me a lot to understand the topic. I think I've covered it now in the updated list.

And your second comment: I can't see a place where I don't use CamelCaps?

[webmozart]

Thanks for clarifying @wouterj!

[weaverryan]

This is much better explained! Though I'll admit, the subtleties between the Default and User stuff makes my head spin a little bit still.