玩！错误重载方法值映射与替代方案？答案

【问题标题】：Play! error overloaded method value mapping with alternatives?玩！错误重载方法值映射与替代方案？
【发布时间】：2012-04-10 12:03:40
【问题描述】：

在我的 Play 中定义一个表单！当编译器吐出这个奇怪的错误时控制器：overloaded method value mapping with alternative:...[a bunch of crap]...Error occurred in an application involving default arguments。

这是代码，我不确定是什么原因：

 val jobForm: Form[Job] = Form(
    mapping(
      "id" -> of[Long],
      "end_time" -> text(minLength = 3),
      "start_time" -> text(minLength = 3),
      "client_id" -> of[Long],
      "start_address_type" -> text,
      "start_address" -> text(minLength = 3),
      "start_city" -> text(minLength = 3),
      "start_province" -> text(minLength = 2),
      "start_lat" -> optional(text),
      "start_lng" -> optional(text),
      "comments" -> text,
      "created" -> text,
      "modified" -> text,
      "canceled" -> of[Boolean],
      "started" -> of[Boolean],
      "completed" -> of[Boolean],
      "user_id" -> optional(of[Long]),
      "start_order" -> optional(number),
      "end_order" -> optional(number),
      "account_id" -> of[Long]
    )(Job.apply)(Job.unapply)
  )

【问题讨论】：

标签： scala playframework-2.0

【解决方案1】：

看过剧本！ 2.0 源码。看起来每个mapping() 最多只能有 18 个参数，所以我不得不开始嵌套并创建新的案例类。结果如下：

val jobForm: Form[JobSimple] = Form(
    mapping(
      "id" -> of[Long],
      "end_time" -> text(minLength = 3),
      "start_time" -> text(minLength = 3),
      "client_id" -> of[Long],
      "location" -> mapping(
        "start_address_type" -> text,
        "start_address" -> text(minLength = 3),
        "start_city" -> text(minLength = 3),
        "start_province" -> text(minLength = 2),
        "start_lat" -> optional(text),
        "start_lng" -> optional(text)
        )(JobLocation.apply)(JobLocation.unapply),
      "comments" -> text,
      "created" -> text,
      "modified" -> text,
      "canceled" -> of[Boolean],
      "started" -> of[Boolean],
      "completed" -> of[Boolean],
      "user_id" -> optional(of[Long]),
      "start_order" -> optional(number),
      "account_id" -> of[Long]
    )(JobSimple.apply)(JobSimple.unapply)
  )

【讨论】：

是的，我不知道他们为什么不支持案例类的 22 个字段的限制。