如果前面的函数满足了某些条件，如何使用for-comprehension并跳过运行函数？

Question

我在我的mongo dao中创建了3个复制检查，以检查我的数据库中的3个不同的复制情况。(我知道最好的方法是为它们创建一个复合索引，但不幸的是现在不可能，我需要这些检查)

所以我想这样做，创建这个方法：

  def checkPersonDuplication(person: Person): Future[(ValidationResult, Option[Person])] = for {
    sameSocIdIAndCountryVerification <- {
      logger.info("sameSocIdIAndCountryVerification is running")
      findPersonSameSocIdIAndCountry(person.socId, person.country)
    }
    sameNameAndCountryVerification <- {
      logger.info("sameNameAndCountryVerification is running")
      findPersonSameNameAndCountry(person.name, person.country)
    }
    sameLastNameAndCountryVerification <- {
      logger.info("sameLastNameAndCountryVerification is running")
      findPersonSameByNameAndCountry(person.lname, person.country)
    }
  } yield (sameSocIdIAndCountryVerification, sameNameAndCountryVerification, sameLastNameAndCountryVerification) match {
    case a if a._1.isDefined => (SameSocialSecurityNumberAndCountry, sameSocIdIAndCountryVerification)
    case b if b._2.isDefined => (SameNameAndCountry, sameNameAndCountryVerification)
    case c if c._3.isDefined => (SameLastNameAndCountry, sameLastNameAndCountryVerification)
    case _ => (ValidationSuccess, None)
  }

现在，在创建方法中，我可以这样做：

 checkPersonDuplication(person) map {res => 
      res._1 match {
        case ValidationSuccess => // do something
        case SameSocialSecurityNumberAndCountry => throw DuplicateInsertion(s"???")
        case SameNameAndCountry => throw DuplicateInsertion(s"???")
        case SameLastNameAndCountry => throw DuplicateInsertion(s"???")
        }
  }

我的问题是，如果定义了sameSocIdIAndCountryVerification (因为findPersonSameSocIdIAndCountry返回OptionPerson)，我就不想运行for- checks中的其他检查。

所以我试着在每个后面加上"if“，但是它抛出了NoSuchElementException。实现这一目标的最佳方法是什么？

Answer 1

这个版本避免了不必要的验证，但它并不是特别漂亮：

def checkPersonDuplication(person: Person): Future[(ValidationResult, Option[Person])] = {
  logger.info("sameSocIdIAndCountryVerification is running")
  findPersonSameSocIdIAndCountry(person.socId, person.country).flatMap {
    case x@Some(_) =>
      Future.successful((SameSocialSecurityNumberAndCountry, x))
    case None =>
      logger.info("sameNameAndCountryVerification is running")
      findPersonSameNameAndCountry(person.name, person.country).flatMap {
        case x@Some(_) =>
          Future.successful((SameNameAndCountry, x))
        case None =>
          logger.info("sameLastNameAndCountryVerification is running")
          findPersonSameByNameAndCountry(person.lname, person.country).map {
            case x@Some(_) =>
              (SameLastNameAndCountry, x)
            case None =>
              (ValidationSuccess, None)
          }
      }
  }
}