spray parameter directives

URL上的QueryString，使用paramters directive解析

必传参数(Required parameter)

http://localhost/api?color=blue&backgroundColor=orange
val route =
  parameters('color, 'backgroundColor) { (color, backgroundColor) =>
    complete(s"The color is '$color' and the background is '$backgroundColor'")
  }

可选参数(Optional parameter)

http://localhost/api?color=blue
val route =
  parameters('color, 'backgroundColor.?) { (color, backgroundColor) =>
    val backgroundStr = backgroundColor.getOrElse("<undefined>")
    complete(s"The color is '$color' and the background is '$backgroundStr'")
  }

设置可选参数的默认值(Optional parameter with default value)

http://localhost/api?color=blue等同于http://localhost/api?color=blue&backgroundColor=white

val route =
  parameters('color, 'backgroundColor ? "white") { (color, backgroundColor) =>
    complete(s"The color is '$color' and the background is '$backgroundColor'")
  }

限制参数的值(Parameter with required value)

Ok       http://localhost/api?color=blue&action=true
NotFound http://localhost/api?color=blue&action=false

val route =
  parameters('color, 'action ! "true") { (color) =>
    complete(s"The color is '$color'.")
  }
//note: require value of parameter “color” to be "blue" and extract nothing

反序列化，将字符串转换为强类型(Deserialized parameter)

Ok         http://localhsot/api?color=blue&count=42
BadRequest http://localhost/api?color=blue&count=blue

val route =
  parameters('color, 'count.as[Int]) { (color, count) =>
    complete(s"The color is '$color' and you have $count of it.")
  }