找不到类型为Seq [(String,String)]的Json序列化程序.尝试为此类型实现隐式写入或格式

Question

我想Seq[(String, String)]用Scala播放转换成JSON,但是我遇到了这个错误:

找不到类型为Seq [(String,String)]的Json序列化程序.尝试为此类型实现隐式写入或格式.

我怎样才能解决这个问题？

Answer 1

这取决于你想要达到的目标.说你有Seq[(String, String)]这样的:

val tuples = Seq(("z", "x"), ("v", "b"))

如果您尝试将其序列化如下:

{
  "z" : "x",
  "v" : "b"
}

然后就用吧Json.toJson(tuples.toMap).如果您想要对元组进行自定义表示,可以Writes按照编译器的建议定义:

implicit val writer = new Writes[(String, String)] {
  def writes(t: (String, String)): JsValue = {
    Json.obj("something" -> t._1 + ", " + t._2)
  }
}

编辑:

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

class MyController extends Controller {
  implicit val writer = new Writes[(String, String)] {
    def writes(t: (String, String)): JsValue = {
      Json.obj("something" -> t._1 + ", " + t._2)
    }
  }

  def myAction = Action { implicit request =>
    val tuples = Seq(("z", "x"), ("v", "b"))
    Ok(Json.toJson(tuples))
  }
}