gistfile1.txt

<?php
namespace App\GtsBundle\Form\Transformer;

use Symfony\Component\Form\ValueTransformer\BaseValueTransformer;

class DoctrineCollectionTransformer extends BaseValueTransformer
{

    public function reverseTransform($ids, $collection)
    {
      return $collection;
    }
    
    /**
     * @param Collection $value
     */
    public function transform($value)
    {
        if ($value === null)
        {
          return new \Doctrine\Common\Collections\ArrayCollection;
        }
        
        return $value;
    }
}