错误:必须管理传递给选择字段的实体

首先:我得到的错误是:传递到选择字段的实体必须被管理

我有这些实体:-用户(属于一个或多个团队)-团队(一名或两名用户)-挑战赛(2队)

我想构建一个ChallengeType表单，用户可以在其中为两个团队填写两个用户并创建挑战。我想我需要在这里嵌入表格。

我已经做了一个TeamType Form类:(我希望从中得到一个选择框，其中列出了所有用户)

<?php
namespace Tennisconnect'DashboardBundle'Form'Type;
use Symfony'Component'Form'AbstractType;
use Symfony'Component'Form'FormBuilder;
class TeamType extends AbstractType
{
    public function buildForm(FormBuilder $builder, array $options)
    {
        $builder->add('players', 'entity', array(
            'class' => 'TennisconnectUserBundle:User',
            'multiple' => true
        ));
    }
    public function getName()
    {
        return 'team';
    }
    public function getDefaultOptions(array $options)
    {
        return array('data_class' => 'Tennisconnect'DashboardBundle'Entity'Team');
    }
}

这是ChallengeType表单类:

<?php
namespace Tennisconnect'DashboardBundle'Form'Type;
use Symfony'Component'Form'AbstractType;
use Symfony'Component'Form'FormBuilder;
class ChallengeType extends AbstractType
{
    public function buildForm(FormBuilder $builder, array $options)
    {
        $builder->add('teams', 'collection', array('type' => new TeamType()));
    }
    public function getName()
    {
        return 'challenge';
    }
    public function getDefaultOptions(array $options)
    {
        return array('data_class' => 'Tennisconnect'DashboardBundle'Entity'Challenge');
    }
}

挑战实体:

namespace Tennisconnect'DashboardBundle'Entity;
use Doctrine'ORM'Mapping as ORM;
use Tennisconnect'DashboardBundle'Entity'Team;
use Symfony'Component'Validator'Constraints as Assert;
use Doctrine'Common'Collections'ArrayCollection;
/**
* @ORM'Entity
* @ORM'Table(name="challenge")
*/
class Challenge
{
    /**
     * @ORM'Id
     * @ORM'Column(type="integer")
     * @ORM'GeneratedValue(strategy="AUTO")
     */
    protected $id;
    /**
     * @ORM'ManyToMany(targetEntity="Team", mappedBy="teams")
     */
    protected $teams;
    public function __construct()
    {
        $this->teams = new ArrayCollection();
    }
    /**
     * Get id
     *
     * @return integer 
     */
    public function getId()
    {
        return $this->id;
    }
    /**
     * Add teams
     *
     * @param Tennisconnect'DashboardBundle'Entity'Team $teams
     */
    public function addTeam(Team $teams)
    {
        $this->teams[] = $teams;
    }
    /**
     * Get teams
     *
     * @return Doctrine'Common'Collections'Collection 
     */
    public function getTeams()
    {
         return $this->teams;
    }
}

团队实体:

namespace Tennisconnect'DashboardBundle'Entity;
use Doctrine'ORM'Mapping as ORM;
use Symfony'Component'Validator'Constraints as Assert;
use Doctrine'Common'Collections'ArrayCollection;
use Tennisconnect'UserBundle'Entity'User;
use Tennisconnect'DashboardBundle'Entity'Challenge;
use Tennisconnect'DashboardBundle'Entity'Match;
/**
* @ORM'Entity
* @ORM'Table(name="team")
*/
class Team
{
    /**
     * @ORM'Id
     * @ORM'Column(type="integer")
     * @ORM'GeneratedValue(strategy="AUTO")
     */
    protected $id;
    /**
     * @ORM'ManyToMany(targetEntity="Tennisconnect'UserBundle'Entity'User",     mappedBy="teams")
     */
    protected $players;
     /**
     * @ORM'ManyToMany(targetEntity="challenge", inversedBy="teams", cascade=     {"persist"})
     */
    protected $challenges;
    /**
     * @ORM'ManyToMany(targetEntity="Match", inversedBy="teams")
     */
    protected $matches;
    public function __construct()
    {
        $this->players = new ArrayCollection();
    }
    /**
     * Get id
     *
     * @return integer 
     */
    public function getId()
    {
        return $this->id;
    }
    /**
     * Add players
     *
     * @param Tennisconnect'UserBundle'Entity'User $players
     */
    public function addUser(User $players)
    {
        $this->players[] = $players;
    }
    /**
     * Get players
     *
     * @return Doctrine'Common'Collections'Collection 
     */
    public function getPlayers()
    {
        return $this->players;
    }
    /**
     * Add matches
     *
     * @param Tennisconnect'DashboardBundle'Entity'Match $matches
     */
    public function addMatch(Match $matches)
    {
        $this->matches[] = $matches;
    }
    /**
     * Get matches
     *
     * @return Doctrine'Common'Collections'Collection 
     */
    public function getMatches()
    {
        return $this->matches;
    }
    /**
     * Add challenges
     *
     * @param Tennisconnect'DashboardBundle'Entity'challenge $challenges
     */
    public function addchallenge(challenge $challenges)
    {
        $this->challenges[] = $challenges;
    }
    /**
     * Get challenges
     *
     * @return Doctrine'Common'Collections'Collection 
     */
    public function getChallenges()
    {
        return $this->challenges;
    }
}

挑战控制器:

class ChallengeController extends Controller
{
    public function newAction()
    {
        $challenge = new Challenge();
        $form = $this->createForm(new ChallengeType(), $challenge);
        return $this->render('TennisconnectDashboardBundle:Challenge:new.html.twig', array('form' => $form->createView()));
    }
}