File upload: How to exclude a MIME type using asserts?

Question

In Symfony I can accept MIME types using:

/**
  * @Assert\File( maxSize="10M", mimeTypes={"application/pdf", "image/png"} )
  */
public $file;

But how can I exclude something from that list? Let's say, I want to allow all uploads except for PHP files?

Answer 1

You could implement a Callback constraint via an assert. One advantage of this method is you can apply the error message to any field (or fields) in your form.

use Symfony\Component\Validator\ExecutionContext;

/**
 * @ORM\Entity()
 * @Assert\Callback(methods={"validateFile"})
 */
class MyEntity
{

    public function validateFile(ExecutionContext $context)
    {
        $path = $context->getPropertyPath();
        if (/* $this->file is not in allowed mimeTypes ... */) {
            $context->setPropertyPath($path . '.file');
            $context->addViolation("Invalid file mimetype", array(), null);
        }
    }
}