Symfony 3，ArrayCollection的remove（）导致错误“警告：isset中的非法偏移类型或为空”

Question

I have a Wishlist entity, which has relationship with a Product entity using MTM Doctrine annotation. I have the definition that $products is an Array Collection In Wishlist's __construct() and that's why I have addProduct() and removeProduct() methods. So, the class has the following view:

<?php

namespace WishlistBundle\Entity;

use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\ORM\Mapping as ORM;
use ShopBundle\Entity\Product;

/**
 * Wishlist
 *
 * @ORM\Table(name="wishlist")
 * @ORM\Entity()
 */
class Wishlist
{
    /**
     * @var int
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @ORM\ManyToMany(targetEntity="ShopBundle\Entity\Product")
     * @ORM\JoinTable(
     *     name="mtm_products_in_wishlists",
     *     joinColumns={
     *     @ORM\JoinColumn(
     *     name="wishlist_id",
     *     referencedColumnName="id"
     *     )
     * },
     *     inverseJoinColumns={
     *     @ORM\JoinColumn(
     *     name="product_id",
     *     referencedColumnName="id",
     *     unique=true
     *     )
     * }
     *     )
     */
    private $products;

    ...

     /**
     * @param Product $product
     */
    public function addProduct(Product $product)
    {
        $this->products->add($product);
    }

    /**
     * @param Product $product
     */
    public function removeProduct(Product $product)
    {
        $this->products->remove($product);
    }

    /**
     * Get products.
     *
     * @return string
     */
    public function getProducts()
    {
        return $this->products;
    }

    /**
     * Wishlist constructor.
     */
    public function __construct()
    {
        $this->products  = new ArrayCollection();
    }
}

In my Controller, I have a place where I try to use removeProduct() method. I use it in the following way:

$wishlist->removeProduct($product);

But I receive the following error:

Warning: Illegal offset type in isset or empty (500 Internal Server Error)

It is at the line in

vendor\doctrine\collections\lib\Doctrine\Common\Collections\ArrayCollection.php at line 126

It has the following view:

public function remove($key)
{
    if ( ! isset($this->elements[$key]) && ! array_key_exists($key, $this->elements)) {
        return null;
    }
}

At the same time, addProduct() works fine. What do I do wrong? How can this issues be solved?

Answer 1

What you are looking for is ArrayCollection's removeElement($element) function and not remove($key) function.

As indicated by their definitions remove($key) function removes the element at the specified index ($key) from a collection, while removeElement($element) removes the specified element from the collection, if it is found.

Since you are trying to remove a product as an element and not by its index you should use removeElement($product).

Doctrine ArrayCollection API Reference here