我正在嘗試驗證方法的參數(shù)是否為空，但找不到解決方案...有人可以告訴我該怎么做嗎？我正在嘗試這樣的事情：  def buildNormalCategory(user: User, parent: Category, name: String, description: String): Either[Error,Category] = {    val errors: Option[String] = for {      _ <- Option(user).toRight("User is mandatory for a normal category").right      _ <- Option(parent).toRight("Parent category is mandatory for a normal category").right      _ <- Option(name).toRight("Name is mandatory for a normal category").right      errors : Option[String] <- Option(description).toRight("Description is mandatory for a normal category").left.toOption    } yield errors    errors match {      case Some(errorString) => Left( Error(Error.FORBIDDEN,errorString) )      case None =>  Right( buildTrashCategory(user) )    }  }