symfony2 Doctrine Entity Relationships One-To-Many, Bidirectional

Example

This bidirectional mapping requires the mappedBy attribute on the OneToMany association and the inversedBy attribute on the ManyToOne association.

A bidirectional relationship has both an owning and inverse side. OneToMany relationships can use join tables, so you have to specify an owning side. The OneToMany association is always the inverse side of a bidirectional association.

<?php

namespace AppBundle\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 * @ORM\Table(name="users")
 */
class User
{
    /**
     * @var int
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;
     
     /**
     * @var string
     *
     * @ORM\Column(name="username", type="string", length=255)
     */
    protected $username;

    /**
     * @var Group|null
     *
     * @ORM\ManyToOne(targetEntity="AppBundle\Entity\Group", inversedBy="users")
     * @ORM\JoinColumn(name="group_id", referencedColumnName="id", nullable=true)
     */
    protected $group;

    /**
     * @param string $username
     * @param Group|null $group
     */
    public function __construct($username, Group $group = null)
    {
        $this->username = $username;
        $this->group = $group;
    }

    /**
     * Set username
     *
     * @param string $username
     */
    public function setUsername($username)
    {
        $this->username = $username;
    }

    /**
     * Get username
     *
     * @return string 
     */
    public function getUsername()
    {
        return $this->username;
    }

    /**
     * @param Group|null $group
     */
    public function setGroup(Group $group = null)
    {
        if($this->group !== null) {
            $this->group->removeUser($this);
        }

        if ($group !== null) {
            $group->addUser($this);
        }

        $this->group = $group;
    }

    /**
     * Get group
     *
     * @return Group|null
     */
    public function getGroup()
    {
        return $this->group;
    }
}

<?php

namespace AppBundle\Entity;

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

/**
 * @ORM\Entity
 * @ORM\Table(name="groups")
 */
class Group
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @ORM\Column(name="name", type="string", length=255)
     */
    protected $name;

    /**
     * @ORM\OneToMany(targetEntity="AppBundle\Entity\User", mappedBy="group")
     */
    protected $users;

    /**
     * @param string $name
     */
    public function __construct($name)
    {
        $this->name = $name;
        $this->users = new ArrayCollection();
    }

    /**
     * @return string 
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     * @param string $name
     */
    public function setName($name)
    {
        $this->name = $name;
    }

    public function addUser(User $user)
    {
        if (!$this->getUsers()->contains($user)) {
            $this->getUsers()->add($user);
        }
    }

    public function removeUser(User $user)
    {
        if ($this->getUsers()->contains($user)) {
            $this->getUsers()->removeElement($user);
        }
    }

    public function getUsers()
    {
        return $this->users;
    }

    public function __toString()
    {
        return (string) $this->getName();
    }
}