找不到Seq [(String，String)]类型的Json序列化器.尝试为此类型实现隐式的Writes或Format

问题描述

我想通过Scala播放将Seq[(String, String)]转换为JSON，但我遇到此错误:

I want to convert a Seq[(String, String)] into JSON with Scala play, but I face this error:

我该如何解决?

推荐答案

这取决于您要实现的目标.假设您有这样的Seq[(String, String)]:

It depends on what you're trying to achieve. Say you have a Seq[(String, String)] like this:

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

如果您尝试按以下方式进行序列化:

If you are trying to serialize it as following:

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

然后只需使用Json.toJson(tuples.toMap).如果您希望对元组进行一些自定义表示，则可以按照编译器的建议定义Writes:

Then just use Json.toJson(tuples.toMap). If you'd like to have some custom representation of your tuples you can define a Writes as the compiler suggests:

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))
  }
}

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