Symfony 2. How to save an entity passed to a form?

Question

symfony

There is an entity "User" - represents a user in the system. There is a "Role" entity - this entity represents the user's role in the system. Between themselves they are connected "ManyToMany".

#  Часть кода из файла .../Entity/User.php которая относится к Role сущности
/**
 * @ORM\ManyToMany(targetEntity="Role", inversedBy="users")
 */
private $roles;

public function __construct() {
    $this->roles = new ArrayCollection();
}

public function getRoles() {
    return $this->roles->toArray();
}

#  Часть кода из файла .../Entity/Role.php которая относится к User сущности
/**
 * @ORM\ManyToMany(targetEntity="User", mappedBy="roles")
 */
private $users;

public function __construct() {
    $this->users = new ArrayCollection();
}

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

Both entities perform their duties perfectly. Now we build the user edit form:

#  Часть кода из файла .../Form/Type/UserType.php
$builder
    ->add('username', 'text')
    ->add('email', 'email')
    ->add('roles', 'entity', ['class' => 'AcmeUserBundle:Role', 'property' => 'name'])
    ->add('save', 'submit');

#  Часть кода из файла .../Controller/UserController.php
if ($form->isValid()) {
    $em->persist($user);
    $em->flush();
}

We get the form. The form has a drop-down list (select tag) "User role", where you can select any role, click save and... an error occurs:

ContextErrorException: Catchable Fatal Error: Argument 1 passed to Doctrine\Common\Collections\ArrayCollection::__construct() must be of the type array, object given, called in /Users/Gee/Sites/sirius.pro/vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php on line 547 and defined in /Users/Gee/Sites/sirius.pro/vendor/doctrine/collections/lib/Doctrine/Common/Collections/ArrayCollection.php line 47

Answer 1

Show more code. Somewhere you are wrong.
Judging by the error, somewhere the system creates an ArrayCollection, which should receive an array, and your entity is fed to it