Task.php

    /**
     * @ORM\ManyToMany(targetEntity="Site", mappedBy="tasks", cascade={"all"})
     */
    private $sites;

    /**
     * @ORM\ManyToMany(targetEntity="User", mappedBy="tasks", cascade={"all"})
     */
    private $users;

    public function __construct() {
        $this->users = new \Doctrine\Common\Collections\ArrayCollection();
        $this->sites = new \Doctrine\Common\Collections\ArrayCollection();
    }

    /**
     * Add sites
     *
     * @return Ev\MyEvBundle\Entity\Site $sites
     */
	public function addSite(\Ev\MyEvBundle\Entity\Site $sites)
    {
	$site->addTask($this);
        $this->sites[] = $sites;
    }

    /**
     * Get sites
     *
     * @return Doctrine\Common\Collections\Collection
     */
    public function getSites()
    {
    	return $this->sites;
    }

    /**
     * Set sites
     *
     * @return Doctrine\Common\Collections\Collection
     */
    public function setSites(Doctrine\Common\Collections\Collection $sites)
    {
    	$this->sites = $sites;
    }

    /**
     * Add users
     *
     * @param Ev\MyEvBundle\Entity\User $users
     */
    public function addUser(\Ev\MyEvBundle\Entity\User $users)
    {
        $this->users[] = $users;
    }

    /**
     * Get users
     *
     * @return Doctrine\Common\Collections\Collection
     */
    public function getUsers()
    {
        return $this->users;
    }

    /**
     * Set users
     *
     * @return Doctrine\Common\Collections\Collection
     */
    public function setUsers(Doctrine\Common\Collections\Collection $users)
    {
    	$this->users = $users;
    }




_______________________________________________

Site.php


    /**
     * @ORM\ManyToMany(targetEntity="Task", inversedBy="sites")
     * @ORM\OrderBy({"name" = "ASC"})
     * @ORM\JoinTable(name="site_tasks",
     * 	joinColumns={@ORM\JoinColumn(name="site_id", referencedColumnName="id", nullable=true)},
     * 	inverseJoinColumns={@ORM\JoinColumn(name="task_id", referencedColumnName="id", nullable=true)}
     * )
     */
    private $tasks;

    public function __construct(){
        $this->tags = new \Doctrine\Common\Collections\ArrayCollection();
        $this->tasks = new \Doctrine\Common\Collections\ArrayCollection();
    }


    /**
     * Add tasks
     *
     * @param Ev\MyEvBundle\Entity\Task $tasks
     */
    public function addTask(\Ev\MyEvBundle\Entity\Task $tasks)
    {
        $this->tasks[] = $tasks;
    }

    /**
     * Get tasks
     *
     * @return Doctrine\Common\Collections\Collection
     */
    public function getTasks()
    {
        return $this->tasks;
    }

    /**
     * Set Tasks
     *
     * @param Doctrine\Common\Collections\Collection $tasks
     */
    public function setTasks(\Ev\MyEvBundle\Entity\User $tasks)
    {
    	$this->tasks = $tasks;
    }