json - Play 2.2.2 (Scala) Json parse as List[Class] 问题

Question

给定以下 Json 数组:

{
    "success": true,
    "data": [
        {
            "id": 594,
            "stage_id": 15,
            "title": "test deal",
            "value": 0,
            "currency": "EUR",
            "add_time": "2014-03-18 17:45:51",
            "update_time": "2014-03-24 13:30:27",
            "stage_change_time": "2014-03-24 13:30:27",
            "active": true,
            "deleted": false,
            "status": "open",
            "expected_close_date": null,
            "stage_order_nr": 1,
            "person_name": "test"
        },
        {
            "id": 601,
            "stage_id": 15,
            "title": "test deal2 deal",
            "value": 0,
            "currency": "EUR",
            "add_time": "2014-03-24 14:11:00",
            "update_time": "2014-03-24 14:11:00",
            "stage_change_time": "2014-03-24 14:11:00",
            "active": true,
            "deleted": false,
            "status": "open",
            "expected_close_date": null,
            "stage_order_nr": 1,
            "person_name": "test deal2"
        }
    ],
    "additional_data": {
        "pagination": {
            "start": 0,
            "limit": 100,
            "more_items_in_collection": false
        }
    }
}

我想从中得到一个交易列表，我正在尝试这样做

case class Deal(id: Long, stage_id: Long)

  def getAllDeals(): List [Deal] = {

    var holder : WSRequestHolder = WS.url(PipeDriveApiBaseUrl + "/deals")

    val complexHolder: WSRequestHolder = holder.withQueryString("filter_id" -> "9", "api_token" -> SalesManagerApiKey)
    val futureResponse: Future[Response] = complexHolder.get()

    implicit val dealReader = Json.reads[List[Deal]]

    val futureJson: Future[List[Deal]] = futureResponse.map(
      response => (response.json \ "data").validate[List[Deal]].get
    )

我得到与隐式读取值相关的异常No unapply function found。但是注释掉它，我会得到 No Json deserializer found for type List[models.Deal]。尝试为此类型实现隐式读取或格式。

我无法用这些答案解决问题 here和 here .我错过或误解了什么？

Answer 1

不是为 List[Deal] 定义一个隐式的 Json.reads，而是为 Deal 创建一个:

implicit val dealReader = Json.reads[Deal]

Play 已经内置了一个用于列表的隐式 JSON 读取转换器。实际上，它有一个用于所有 Traversables。你可以look at the code , 但它有点难读。问题是:Play 可以将 JSON 列表转换为 List 对象。它不知道如何读取/转换 Deal，这就是为什么您需要上面提到的隐式定义。