private function getPropertyMap($class)
    {
        $output['meta'] = $meta = $this->em->getClassMetadata($class);
        $output['fields']       = $meta->getFieldNames();
        $output['associations'] = $meta->getAssociationNames();

        $output['fields'] = array_filter(
            $output['fields'],
            function($fieldName) use ($output) {
                if (in_array($fieldName, $output['associations'])) {
                    return false;
                } else {
                    return true;
                }
            }
        );

        return $output;
    }