Question

当我在组合器http://www.playframework.com/documentation/2.2.x/ScalaJsonCombinators的文档中尝试第一个例子时，它会在repl中引发错误，并且在播放应用程序中使用scala文件找不到值（尝试使用play 2.2.0并播放2.1。 1） - 从repl追溯：

Welcome to Scala version 2.10.2 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_25).
Type in expressions to have them evaluated.
Type :help for more information.

scala> :paste
// Entering paste mode (ctrl-D to finish)

import play.api.libs.json._
import play.api.libs.functional.syntax._

val customReads: Reads[(String, Float, List[String])] = 
  (JsPath \ "key1").read[String](email keepAnd minLength(5)) and 
  (JsPath \ "key2").read[Float](min(45)) and
  (JsPath \ "key3").read[List[String]] 
  tupled


// Exiting paste mode, now interpreting.

<console>:16: error: not found: value tupled
        tupled
        ^
<console>:11: error: not found: value email
        (JsPath \ "key1").read[String](email keepAnd minLength(5)) and 
                       ^

scala>

那该怎么解决？

THX

Answer 1

两个问题。首先，您还需要一次导入：

import play.api.libs.json.Reads._

其次，在“minLength”和“min”之类的函数变得通用之前，可能会编写doc，以处理不仅仅是String和Float。所以你必须指定那些类型：

val customReads: Reads[(String, Float, List[String])] =
    (JsPath \ "key1").read[String](email keepAnd minLength[String](5)) and
    (JsPath \ "key2").read[Float](min[Float](45)) and
    (JsPath \ "key3").read[List[String]]
    tupled

这是我读过的讨论，我发现有关此方面的信息：

play-framework Google Group Discussion

playframework组合器文档引发错误：找不到 - 为什么？

1 个答案: