field array type in entity for form choice type field symfony - forms

Question

I would like to create a UserForm for create user in my system backend.
I use a entity with a 'role' field as type array
I want use a select choice field type Form with that entity field.
I use a transformer class system for convert data between Entity and form.
but I turn around in my head and nothing run correctly.
When I use options 'multiple' of choice type, my field display correctly but I don't want to display and select multiple value for this field.
I have Notice: Undefined offset: 0 error
or
I have ContextErrorException: Notice: Array to string conversion
Here few essential code :
UserForm class
$builder->add($builder->create('roles', 'choice', array(
'label' => 'I am:',
'mapped' => true,
'expanded' => false,
'multiple' => false,
'choices' => array(
'ROLE_NORMAL' => 'Standard',
'ROLE_VIP' => 'VIP',
)
))->addModelTransformer($transformer));
transformer Class
class StringToArrayTransformer implements DataTransformerInterface
{
public function transform($array)
{
return $array[0];
}
public function reverseTransform($string)
{
return array($string);
}
}
controller method
$user = new User(); //init entity
$form = $this->createForm(new UserForm(), $user);
$form->handleRequest($request);
if ($form->isValid())
{
$em = $this->getDoctrine()->getManager();
$em->persist($form);
$em->flush();
return $this->redirect($this->generateUrl('task_success'));
}
entity part
/**
* #ORM\Column(name="roles", type="array")
*/
protected $roles;
public function getRoles()
{
return $this->roles;
}
public function setRoles(array $roles)
{
$this->roles = $roles;
return $this;
}
My field roles entity must be a array for run correctly the security component Symfony
can you help me to understand why this field form refuse to display ?
I already readed others questions in same issue but there is anything that I don't understand because nothing help me to resolve my problem.
If you can help me with MY particular context...
Thank for support

Answer 1

because security symfony component integration
If you only need the "getRoles" method because of the interface you are implementing, it is simpler (and cleaner) to do the following:
Change the entities field again to role with type string
Rename your getter and setter to getRole() and setRole()
and add a getRoles method like this:
public function getRoles()
{
return array($this->role);
}
In your form type, change the field name to "role" and 'multiple' => false
Remove your model transformer
This should be the solution ;)