类型列表采用类型参数（播放中发生编译错误）

Question

当前正在通过Play学习RESTFUL API的基础知识，并且遇到了问题：正在学习一些长期的教程，并认为使用正确的scala语法会失败！需要帮助，谢谢

 package controllers

import play.api.libs.json.Json
import javax.inject.Inject
import play.api.Configuration
import play.api.mvc.{AbstractController, ControllerComponents}

import scala.concurrent.ExecutionContext


class PlacesController @Inject()(cc: ControllerComponents)(implicit assetsFinder: AssetsFinder, ec: ExecutionContext, configuration: Configuration)
  extends AbstractController(cc) {


  case class PlacesController(id: Int, name: String)

  val thePlaces: List = List(
    thePlaces(1, "newyork"),
    thePlaces(2, "chicago"),
    thePlaces(3, "capetown")
  )

  implicit val thePlacesWrites = Json.writes[PlacesController]

  def listPlaces = Action {
    val json = Json.toJson(thePlaces)
    Ok(json)
  }}

Answer 1

您的代码有很多问题。您正在定义thePlaces，同时在定义的右侧调用thePlaces本身。

而且，您的命名令人困惑。

尝试一下：

final case class Place(id: Int, name: String)

object Place {
  implicit val placeWrites = Json.writes[Place]
}

class PlacesController ... {

  val thePlaces: List = List(
    Place(1, "newyork"),
    Place(2, "chicago"),
    Place(3, "capetown")
  )

  def listPlaces = Action {
    val json = Json.toJson(thePlaces)
    Ok(json)
  }
}