public function getField($fieldName, $biDirectional = false, $contentTypeName = null, $contentTypeId = null)
    {
        if ($biDirectional) {
            $filter = function ($el) use ($fieldName, $contentTypeName, $contentTypeId) {
                /** @var Entity\Relations $el */
                if ($el->getFromContenttype() === $fieldName && $el->getFromContenttype() === $el->getToContenttype() && $el->getToId() == $contentTypeId) {
                    $el->actAsInverse();

                    return true;
                }
                if ($el->getToContenttype() === $fieldName && $el->getFromContenttype() === $contentTypeName) {
                    return true;
                }
                if ($el->getFromContenttype() === $fieldName && $el->getToContenttype() === $contentTypeName) {
                    $el->actAsInverse();

                    return true;
                }

                return false;
            };

            return $this->filter($filter);
        }

        return $this->filter(function ($el) use ($fieldName) {
            /** @var Entity\Relations $el */
            return $el->getToContenttype() === $fieldName;
        });
    }