toJson(Map("成功" - > true,"message" - > str))无法在play2中编译

Question

这是我的代码:

import play.api.mvc._
import play.api.libs.json._
import play.api.libs.json.Json._
import play.api.libs.json.Writes._

class BaseController extends Controller with Secured with DefaultWrites {

  private implicit def str2json(str: String) = new {
    def asSuccessJson = toJson(Map("success" -> true, "message" -> str)) // (*)
    def asFailedJson = toJson(Map("success" -> false, "message" -> str)) // (*)
  }

}

但它无法在两(*)行编译.错误消息是:

Multiple markers at this line
- No Json deserializer found for type scala.collection.immutable.Map[java.lang.String,Any]. Try 
 to implement an implicit Writes or Format for this type.
- not enough arguments for method toJson: (implicit tjs: 
     play.api.libs.json.Writes[scala.collection.immutable.Map[java.lang.String,Any]])
     play.api.libs.json.JsValue.Unspecified value parameter tjs.

我必须把它写成:

def asSuccessJson = toJson(Map("success" -> true.toString, "message" -> str))

注意事项true.toString.它很有效但很无聊.

怎么解决？

Answer 1

这很合乎逻辑:您尝试将异构映射转换为JsValue:

Map("success" -> true, "message" -> str)是一个Map[String, Any].

没有隐式作者能够将a转换Map[String, Any]为a JsValue(并且不能有任何).

当你编写时Map("success" -> true.toString, "message" -> str),你创建一个Map [String,String],并且有一个编写器.

我会写:

def asSuccessJson = JsObject(Seq("success" -> JsBoolean(true), "message" -> JsString(str))) // (*)

顺便说一句,JSON API肯定会在Play 2的下一个版本中"美化"一下......