[Form] Add shortcuts to set data class and validation groups

[stloyd]

Thanks to those simple shortcuts, when declaring forms as services, you can simply set the data class and/or validation groups.

Sample config:

<service id="acme.form.type.user" class="%acme.form.type.user.class%">
    <call method="setDataClass">
        <argument>%some_default_data_class%</argument>
    </call>
    <call method="setValidationGroups">
        <argument>%some_default_groups%</argument>
    </call>
    <tag name="form.type" alias="acme_user_form" />
</service>

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Tests pass?	yes*
License	MIT
Doc PR	n/a (yet)

* - will fix if not =)

[arnolanglade]

👍

[tadcka]

+1

[webmozart]

I see this a little problematic. How do we decide which options should support a setter and which shouldn't?

Why don't you pass these values to the constructor of your form type if you need this option?

[arnolanglade]

@webmozart : I understand the problematic, validation group and data classes are most common form options for our application. It can be useful when your form is related to a entity and you want to validate it (for a basic usage).

[stof]

@stloyd This would not help here: you would need to have the setter in your own form type class, not in the form type (which will generally not be the type used by your form). Your sample code does not correspond to your PR

[webmozart]

I don't want to merge this PR because of my aforementioned concerns. However, I think the underlying use case is valid and opened a new ticket for that: #10505