Hi @desarrolla2, thank you for suggesting this feature! Can you give an example when this would be useful? I don't quite understand what you propose.

I will tell you my current use case.

I have 2 entities: User that extends FOSUser and Profile that contains firstName, lastName, Address, and others.

Now for a current promotion, i need to create a landing page with some fields from entity User and some fields from entity Profile.

Then i need create a model with this form:

<?php
namespace Sod\WebBundle\Form\Model;

use Symfony\Component\Validator\Constraints as Assert;
/** Here are my current implementation **/
use Sod\WebBundle\Form\Validator\Constraint\UniqueField;

/**
 * LandingRegistrationModel
 */
class LandingRegistrationModel
{
    /**
     * @Assert\NotBlank()
     * @Assert\Length( min=3, max=30 )
     * @UniqueField(entity="CoreBundle:User", field="username", fieldName="nombre de usuario")
     */
    public $userName;

    /**
     * @Assert\NotBlank()
     * @Assert\Length( min=3, max=300 )
     * @Assert\Email()
     * @UniqueField(entity="CoreBundle:User", field="email", fieldName="email")
     */
    public $email;

    /**
     * @Assert\NotBlank()
     * @Assert\Length( min=3, max=30 )
     */
    public $plainPassword;

    /**
     * @Assert\NotBlank()
     * @Assert\Length( min=3 )
     */
    public $firstName;

    /**
     * @Assert\NotBlank()
     * @Assert\Length( min=3 )
     */
    public $lastName;

    /**
     * @Assert\NotBlank()
     * @Assert\Length( min=3 )
     */
    public $city;

    /**
     * @Assert\NotBlank()
     * @Assert\Length( min=3 )
     * @Assert\Regex("/^[0-9]{2,3}-? ?[0-9]{6,7}$/")
     */
    public $phone;
}

later in controller y will use it well

<?php

$form = $this->createForm(new LandingRegistrationType(), new LandingRegistrationModel());

I would have said that this PR will indirectly allow you to do such a thing, but it's actually more complex:

• We need to remove the check about the repository being able to support the current object
• The UniqueEntity implementation relies on the Doctrine ClassMetadata of the validated object, and your intermediate object isn't an entity.

I think it's a very particular use case and it does not belong to the UniqueEntity constraint responsibility, because you're applying this constraint on a non-entity object as an intermediate. IMO you'll need your own custom constraint.
Why do you need this intermediate object in the first place ? Is there anything preventing you to define a form with appropriated fields, relying on both Profile and FOSUser entities ? You don't need an intermediate model for this.

Sorry if I misunderstood your use case.

EDIT: After reading the following comments and having experienced this myself, I fully agree we need something like this.

@ogizanagi sorry if I did not explain properly, but I think using intermediate objects for form validation is the right use.

If you always use your entities to validate forms, there are many cases where you can be restricted, here are some examples.

1- complex forms that need several entities.
2- validations require different forms depending on the part of the application in which you are.

I also would like this feature. I do my validation on DTO's rather then on the entities themselves.

👍
This is useful in CQRS context.
I validate my commands. But I have to create a custom UniqueEntity validator like @desarrolla2 did.

Any news on this? I thought entityClass addressed this issue but I was mistaken.

I suggest to close this old issue either as duplicate of #22592 or fixed by #15002.