Symfony2和Doctrine2：removeElement不起作用 [英] Symfony2 & Doctrine2 : removeElement doesn't work

问题描述

我在Symfony2和学说中有一个小项目，我正在尝试更新2个相关实体：

I'm have a small project in Symfony2 and doctrine, and I'm trying to update 2 related entities:

成员&汽车

$carMembers = $car->getMembers();
echo count($carMembers); // --> show 2
echo get_class(carMembers[0]); // --> show MyCars\WSBundle\Entity\Member
$car->removeMember($member);
$em->persist($car);
$em->flush();

$carMembers= $car->getMembers();
echo count($carMembers); // --> show 1
echo get_class(carMembers[0]); // --> show MyCars\WSBundle\CarsController !!!

有我的实体：

汽车

/**
 * @ORM\ManyToMany(targetEntity="Member", mappedBy="cars")
 */
private $members;

/**
 * Remove Member
 *
 * @param MyCars\WSBundle\Entity\Member $member
 */
public function removeMember(\MyCars\WSBundle\Entity\Member $member)
{
    $this->members->removeElement($member);
    $member->removeCar($this);
}

会员

/**
 * @ORM\ManyToMany(targetEntity="Car", cascade={"persist"})
 * @ORM\JoinTable(name="cars_membres",
 * joinColumns={@ORM\JoinColumn(name="member_id", referencedColumnName="member_id")},
 * inverseJoinColumns={@ORM\JoinColumn(name="car_id", referencedColumnName="car_id")}
 * )
 */
private $cars;

推荐答案

请确保在类构造函数中初始化ArrayCollection，如果要使用功能添加，包含或 removeElement

Make sure to initialise the ArrayCollection in the class constructor, if you want to use the functions add, contains or removeElement

<?php

// ...

use Doctrine\Common\Collections\ArrayCollection;

class Car
{
    /**
     * @MongoDB\Id
     */
    protected $members;

    /**
     * General constructor
     */
    public function __construct()
    {
        $this->members = new ArrayCollection();
    }

    /**
     * @param Member $member
     * @return $this
     */
    public function addMember(Member $member)
    {
        if (!$this->hasMember($member)) {
            $this->members->add($member);
        }

        return $this;
    }

    /**
     * @param Member $member
     * @return $this
     */
    public function removeMember(Member $member)
    {
        if ($this->hasMember($member)) {
            $this->members->removeElement($member);
        }

        return $this;
    }

    /**
     * @return mixed
     */
    public function getMembers()
    {
        return $this->tags;
    }

    /**
     * @param Member $member
     * @return mixed
     */
    public function hasTag(Member $member)
    {
        return $this->members->contains($member);
    }
}

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