// src/AppBundle/Entity/Product.php
namespace AppBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Validator\Constraints as Assert;
use Symfony\Component\Validator\GroupSequenceProviderInterface;

/**
 * @ORM\Entity
 */
class Product implements GroupSequenceProviderInterface
{
    /**
     * @ORM\Column(type="text", nullable=true)
     *
     * @Assert\Type(type="string")
     * @Assert\NotBlank(groups={"Product_Active"})
     */
    protected $name;

    /**
     * @ORM\OneToMany(targetEntity="Offer")
     *
     * @Assert\Valid(traverse=true)
     */
    protected $offers;

    public function getGroupSequence()
    {
        $groups = ['Product'];

        if ($this->isActive()) {
            $groups[] = 'Product_Active';
        }

        return $groups;
    }
}

// src/AppBundle/Entity/Offer.php
namespace AppBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Validator\Constraints as Assert;

/**
 * @ORM\Entity
 */
class Offer
{
    /**
     * @ORM\Column(type="decimal", precision=10, scale=2, nullable=true)
     *
     * @Assert\Type(type="string")
     * @Assert\Range(min=0)
     * @Assert\NotNull(groups={"Product_Active"})
     */
    protected $price;
}