DunglasApiBundle "IS NULL" custom filter

api.yml

    resource.empty_filter:
        class:    "Foo\AppBundle\Api\Filter\EmptyFilter"
        arguments:
            - @doctrine
            - @api.iri_converter
            - @property_accessor

EmptyFilter.php

<?php

namespace Foo\AppBundle\Api\Filter;

use Dunglas\ApiBundle\Doctrine\Orm\Filter\AbstractFilter;

use Doctrine\Common\Persistence\ManagerRegistry;
use Doctrine\ORM\QueryBuilder;
use Dunglas\ApiBundle\Api\IriConverterInterface;
use Dunglas\ApiBundle\Api\ResourceInterface;

use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\PropertyAccess\PropertyAccessorInterface;

/**
 * Description of EmptyFilter
 *
 * @author thomas.kekeisen
 */
class EmptyFilter extends AbstractFilter
{
    /**
     * @var IriConverterInterface
     */
    private $iriConverter;

    /**
     * @var PropertyAccessorInterface
     */
    private $propertyAccessor;

    /**
     * @param ManagerRegistry           $managerRegistry
     * @param IriConverterInterface     $iriConverter
     * @param PropertyAccessorInterface $propertyAccessor
     * @param null|array                $properties       Null to allow filtering on all properties with the exact strategy or a map of property name with strategy.
     */
    public function __construct(
        ManagerRegistry $managerRegistry,
        IriConverterInterface $iriConverter,
        PropertyAccessorInterface $propertyAccessor,
        array $properties = null
    )
    {
        parent::__construct($managerRegistry, $properties);

        $this->iriConverter = $iriConverter;
        $this->propertyAccessor = $propertyAccessor;
    }

    /**
     * {@inheritdoc}
     */
    public function apply(ResourceInterface $resource, QueryBuilder $queryBuilder, Request $request)
    {
        $metadata = $this->getClassMetadata($resource);
        $fieldNames = array_flip($metadata->getFieldNames());
        foreach ($this->extractProperties($request) as $propertyRange => $value) {
            if (strpos($propertyRange, '-empty') !== false) {
                $property      = str_replace('-empty', '', $propertyRange);

                if (!is_string($value) || !$this->isPropertyEnabled($property)) {
                    continue;
                }

                if (isset($fieldNames[$property])) {

                    $where = sprintf('o.%1$s IS NULL', $property);

                    $queryBuilder
                        ->andWhere($where)
                    ;
                }
            }
        }
    }

    /**
     * Gets the ID from an URI or a raw ID.
     *
     * @param string $value
     *
     * @return string
     */
    private function getFilterValueFromUrl($value)
    {
        try {
            if ($item = $this->iriConverter->getItemFromIri($value)) {
                return $this->propertyAccessor->getValue($item, 'id');
            }
        } catch (\InvalidArgumentException $e) {
            // Do nothing, return the raw value
        }
        return $value;
    }

    /**
     * {@inheritdoc}
     */
    public function getDescription(ResourceInterface $resource)
    {
        $description = [];
        $metadata = $this->getClassMetadata($resource);

        foreach ($metadata->getFieldNames() as $fieldName) {
            $found = isset($this->properties[$fieldName]);
            if ($found || null === $this->properties) {
                $description[$fieldName.'-empty'] = [
                    'property' => $fieldName.'-empty',
                    'type'     => 'string',
                    'required' => false
                ];
            }
        }

        return $description;
    }
}

entity.yml

    resource.address.address:
        parent:    "api.resource"
        class:   "Foo\\AppBundle\\Api\\Address\\AddressResource"
        arguments: [ "Foo\\AppBundle\\Entity\\Address\\Address" ]
        calls:
            -      ...
            -      [ "initFilters", [ [  "@resource.empty_filter",   "@resource.search_filter" ,  "@resource.order_filter" ] ] ]
        tags:      [ { name: "api.resource" } ]