public static function findByUser( $parentId, $parentType, $userId, $type = ModelComment::TYPE_COMMENT ) {

		return static::find()->where( 'parentId=:pid AND parentType=:ptype AND createdBy=:uid AND type=:type', [ ':pid' => $parentId, ':ptype' => $parentType, ':uid' => $userId, ':type' => $type ] )->one();
	}