与symfony 3.4的ManyToMany关系(使用api创建两个表之间的链接)

// src/Entity/Category.php
namespace App\Entity;

use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 */
class Category
{
    // ...

    /**
     * @ORM\ManyToMany(targetEntity="App\Entity\Product", inversedBy="categories")
     * @ORM\JoinTable(name="product_category")
     */
    private $products;

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

    // ...
}

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

use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 */
class Product
{
    // ...

    /**
     * @ORM\ManyToMany(targetEntity="App\Entity\Category", mappedBy="products")
     */
    private $categories;

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

    // ...
}

$ php bin/console doctrine:schema:update --force

// src/Controller/LinkController.php
namespace App\Controller;

use App\Entity\Category;
use App\Entity\Product;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Annotation\Route;

class LinkController extends AbstractController
{
    /**
     * @Route("/link", methods={"POST"})
     */
    public function linkAction(): Response
    {
        $entityManager = $this->getDoctrine()->getManager();

        $category = new Category();
        $category->setName('Category 1');

        $product = new Product();
        $product->setName('Product 1');

        $category->addProduct($product);

        $entityManager->persist($category);
        $entityManager->persist($product);
        $entityManager->flush();

        return new Response('Linked successfully');
    }
}