Doctrine\ODM\MongoDB\Mapping\Driver\YamlDriver::parseDiscriminatorField PHP Method

    private function parseDiscriminatorField($discriminatorField)
    {
        if (is_string($discriminatorField)) {
            return $discriminatorField;
        }
        if (!is_array($discriminatorField)) {
            throw new \InvalidArgumentException('Expected array or string for discriminatorField; found: ' . gettype($discriminatorField));
        }
        if (isset($discriminatorField['name'])) {
            return (string) $discriminatorField['name'];
        }
        if (isset($discriminatorField['fieldName'])) {
            return (string) $discriminatorField['fieldName'];
        }
        throw new \InvalidArgumentException('Expected "name" or "fieldName" key in discriminatorField array; found neither.');
    }