Symfony2 choice constraint/validation on entity field type

Question

I have an entity field type with multiple selection :

$builder
  ->add('products', 'entity', array(
    'class' => 'Acme\MyBundle\Entity\Product',
    'choices' => $this->getAvailableProducts(),
    'multiple' => true,
  ))
;

I would like to add a min/max constraint on this field,

use Symfony\Component\Validator\Constraints\Choice;
...
'constraints' => array(new Choice(array(
    'min' => $min,
    'max' => $max,
    'multiple' => true,
    'choices' => $this->getAvailableProducts()->toArray(),
))),

But in this case, when the form is bound, the value bound for the 'products' field is a doctrine ArrayCollection, the validator throw an exception if an array is not given. "Expected argument of type array, object given"

Does it mean I have to use a 'choice' field in order to use the min/max constraint ?

Answer 1

As you have multiple set to true the validator will receive a collection after binding your form.

You can validate the number of entites in the collection using the count validation constraint.

The Count validation constraint

Validates that a given collection's (i.e. an array or an object that implements Countable) element count is between some minimum and maximum value.