How to validate a file upload in Symfony2 (ImageValidator)? - validation

Question

I am currently developing an application which uses the newest version of Symfony2. I have some problems validating a form which includes a file upload field.
My form code looks like that (shortened):
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilder;
use Symfony\Component\Validator\Constraints\MinLength;
use Symfony\Component\Validator\Constraints\Collection;
class EventEditForm extends AbstractType
{
public function buildForm(FormBuilder $builder, array $options)
{
$builder->add("name", "text", array("required" => true));
//....
$builder->add("image", "file", array("property_path" => false, "required" => false));
}
public function getDefaultOptions(array $options)
{
$collectionConstraint = new \Symfony\Component\Validator\Constraints\Collection(array(
'image' => new \Symfony\Component\Validator\Constraints\Image()
));
$options["validation_constraint"] = $collectionConstraint;
return $options;
}
public function getName()
{
return 'editeventform';
}
}
As you can see here I want to ensure that the uploaded file is an image. I use the form like this:
$form = $this->createForm(new \Trancefans\AdminBundle\Form\EventEditForm(), $event);
But when running this code I get the following error:
Expected argument of type array or Traversable and ArrayAccess, object
given
I really don't know where my fault is. I did it exactly as described in the documentation. Can somebody help me? :-)
BTW: The image is not represented by the event entitiy, but every other field of the form is. I use doctrine.

Answer 1

Symfony\Component\Validator\Constraints\CollectionValidator requires that the data it's validating is an array or an object that implements ArrayAccess and Traversable.
Ensure that your class definition for the $event instance implements ArrayAccess and Traversable so when CollectionValidator::validate() is invoked it can access your values to validate them accordingly.