尝试在1-m关系实体中持久存在时避免重复

Question

我想在尝试保持时避免重复，但是如果在Brands实体中已经设置了品牌名称，那么我在控制器中的逻辑似乎不起作用。因此，如果我尝试将Mercedes作为品牌名称继续存在，那么我会收到此错误“品牌已存在于数据库中”。它应该做的是简单地避免持久化brands并将cars对象与id brands实体保持在一起。我该如何解决这个问题？

1 to Many (Brands to Cars)

注意：删除@UniqueEntity(fields="name", message = "The Brand already exists in database.")的选项不可行，因为我在应用程序的其他位置使用brands表单类型。

CONTROLLER

$form = $this->createForm(new BothType(), null, array('action' => $this->generateUrl('both')));

$form->handleRequest($request);

if ($form->isValid())
{
    $brandsData = $form->get('brands')->getData();
    $carsData = $form->get('cars')->getData();

    $repo = $this->getDoctrine()->getRepository('CarBrandBundle:Brands');
    $brands = $repo->findByName($brandsData->getName());

    //If Brands doesn't exist yet
    if (! $brands)
    {
        $brands = new Brands();
        $brands->setName($brandsData->getName());
        $brands->setOrigin($brandsData->getOrigin());

        $cars = new Cars();
        $cars->setModel($carsData->getModel());
        $cars->setPrice($carsData->getPrice());
        $cars->setBrands($brands);

        $em = $this->getDoctrine()->getManager();
        $em->persist($brands);
        $em->persist($cars);
        $em->flush();
    }
    //If exists
    else
    {
        $cars = new Cars();
        $cars->setModel($carsData->getModel());
        $cars->setPrice($carsData->getPrice());
        $cars->setBrands($brands);

        $em = $this->getDoctrine()->getManager();
        $em->persist($cars);
        $em->flush();
    }

    return new Response('Brands ID:'. $brands->getId().'-Cars ID:'.$cars->getId());
}

FORM TYPE

class BothType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->setMethod('POST')
            ->setAction($options['action'])
            ->add('brands', new BrandsType())
            ->add('cars', new CarsType())
            ->add('button', 'submit', array('label' => 'Add'))
            ;
    }
} 

品牌

/**
 * @ORM\Entity
 * @ORM\Table(name="brands", uniqueConstraints={@ORM\UniqueConstraint(columns={"name"})})
 * @UniqueEntity(fields="name", message = "The Brand already exists in database.")
 */
class Brands
{
    protected $id;
    protected $name;

    /**
     * @ORM\OneToMany(targetEntity="Cars", mappedBy="brands")
     */
    protected $cars;

    public function __construct()
    {
        $this->cars = new ArrayCollection();
    }

    public function getId() { return $this->id; }
    public function setName($name) { $this->name = $name; return $this; }
    public function getName() { return $this->name; }

    public function addCar(\Car\BrandBundle\Entity\Cars $cars)
    {
        $this->cars[] = $cars;
        return $this;
    }

    public function removeCar(\Car\BrandBundle\Entity\Cars $cars)
    {
        $this->cars->removeElement($cars);
    }

    public function getCars()
    {
        return $this->cars;
    }
}

CARS

/**
 * @ORM\Entity
 * @ORM\Table(name="cars")
 */
class Cars
{
    protected $id;
    protected $model;

    /**
     * @ORM\ManyToOne(targetEntity="Brands", inversedBy="cars")
     * @ORM\JoinColumn(name="brands_id", referencedColumnName="id")
     */
    protected $brands;

    public function getId() { return $this->id; }
    public function setModel($model) { $this->model = $model; return $this; }
    public function getModel() { return $this->model; }

    public function setBrands(\Car\BrandBundle\Entity\Brands $brands = null)
    {
        $this->brands = $brands;
        return $this;
    }

    public function getBrands()
    {
        return $this->brands;
    }
}