[Validator] Choice constrait callback service call

[Strate]

Q	A
Bug report?	no
Feature request?	yes
BC Break report?	no
RFC?	no
Symfony version	x.y.z

I would like to get choice list as result of call some service method. Looks like it is impossible for now.

[linaori]

Do you have an example of how you'd like to use this feature? I know that it's already possible, but is a bit of extra work.

[Strate]

For example if I have a list of choices in database, or on a different server, and I want to implement cache, etc

[rpkamp]

The way I do this is by registering the form type as a service, pass it the service that has the choices I need, call that service in the buildForm method, and pass the choices.

Something like this:

<?php

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\Extension\Core\Type\ChoiceType;
use Symfony\Component\Form\FormBuilderInterface

class TaskType extends AbstractType
{
    private $service;

    public function __construct(MyService $service)
    {
        $this->service = $service;
    }

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $choices = $this->service->getSomeChoices();

        $builder->add('foo', ChoiceType::class, ['choices' => $choices]);
    }
}

[Strate]

I do not use Form component in my project, only Validation

[rpkamp]

Well in that case it's probably easiest to create a custom constraint with a custom validator. It's quite easy and gives you all the flexibility to cache and whatever you might need.

See https://symfony.com/doc/current/validation/custom_constraint.html

[Strate]

@rpkamp yes, right now my solution is close to that. Btw, this issue about improve DX in this case.

[xabbuh]

How do you see the feature being used? Would you somehow configure the constraint to let it know where to find the choices? Or do you see it as something that would be done only when the data is being validated by the validator?

[Simperfit]

@xabbuh I think this can be closed. As we can do the same with custom validator/constraint.