Question

这是我之前的question：

的后续内容

假设我需要验证数据结构（例如XML，JSON，HttpRequest等）。我可以定义一个验证函数A => ValidationNel[String, B]和一个包装类：

class Validate[A, B](run: A => ValidationNel[String, B]) {
  def apply(a: A) = run(a)
}

我还将方法andThen和andAlso添加到撰写 Validates：

def andThen[C](other: Validate[B, C]) = new Validate[A, C] {a =>
  this(a) flatMap (b => other(b))
}

def andAlso(other: Validate[A, B]) = new Validate[A, B] (a =>
  (this(a), other(a)) match {
     case ((Success(b), Success(b)) => Success(b)
     case (failure @ Failure(errors), Success(b)) => failure
     case (Success(b), failure @ Failure(errors)) => failure
     case (Failure(errors1), Failure(errors2)) => Failure(errors1 + errors2)
  }
)

现在我可以按如下方式验证数据结构：

case class Header(...)
case class Payload(...)
case class Message(header: Header, payload: Payload)

val validateHeader: Validate[Header, Header] = ...

val validatePayload: Validate[Payload, Payload] = ...

type ValidateMessage = Validate[Message, Message]

val validateMessageHeader =
  new ValidateMessage(m => validateHeader(m.header); m)

val validateMessagePayload =
  new ValidateMessage(m => validatePayload(m.payload); m)

val validateMessage = validateMessageHeader andAlso validateMessagePayload

有意义吗？您如何建议修复/改进它？

使用ValidationNel进行简单验证的示例

0 个答案: