Scala2.13：具有可擴展變數屬性的案例類？

我想創建一個可以合并字串記錄和另一個案例類物體的案例類。

例如：

case class Student(
name: String
age: Int
)
case class Example(
[key:String]: Student
)

現在我想使用Example添加多個屬性，其中attribute可能有 N 個元素，但是所有這些屬性的型別將保持為 Student。這是一個例子：

Example(student1 = Student("name",12),student2=Student("name2",13))

我使用 Case 類的原因是我需要使用 UPickle 庫將其轉換為 JSON，所以我想知道實作相同的可行性。

請注意，Example類不僅包含[key:String]: Student屬性型別，還包含以下內容：

case class Example(
[key:String]: Student,
_logOp: Option[Boolean] = false,
queryName: String,
...
)

案例類的轉換結果：

case class Example(
_logOp: String,
variation: String,
[key:String]: FiltersCaseClass 
/* This line I have added to simplify and make my problem more understandable. Basically the case class would contain some properties like `_logOp` `variation` and then a lot of keys with their values as another case class `FilterCaseClass`
*/
)

應該是這樣的：

{"_logOp":"AND","variation": "en","ids": {"_logOp": "OR","_expressions": [{"value": "242424"},{"value": "242422"}]}}

其中 FilterCaseClass 是：

case class FilterCaseClass(
_logOp: String,
_expressions: Seq[SingleValueFilter]
)

其中 SingleValueFilter 是另一個包含值的案例類

編輯1：

根據 Dymtro 的回答之一：

case class Example(
  m: Map[String, Student],
  _logOp: Option[Boolean] = Some(false),
  queryName: String
)
object Example {
  implicit val rw: ReadWriter[Example] = macroRW
}

write(Example(
  Map("student1" -> Student("name",12), "student2" -> Student("name2",13)),
  Some(true),
  "abc"
))
//{"m":{"student1":{"name":"name","age":12},"student2":{"name":"name2","age":13}},"_logOp":[true],"queryName":"abc"}

我想要的唯一區別是：

{"student1":{"name":"name","age":12},"student2":{"name":"name2","age":13},"_logOp":[true],"queryName":"abc"}

不同之處在于我希望案例類能夠靈活地添加學生類的鍵值對。

uj5u.com熱心網友回復：

你不需要case類Example，在μPickle你可以創建json混合手工構造和case-class構造

import upickle.default.{macroRW, ReadWriter, write} // "com.lihaoyi" %% "ujson" % "0.9.6"

case class Student(
  name: String,
  age: Int
)

object Student {
  implicit val rw: ReadWriter[Student] = macroRW
}

ujson.Obj("student1" -> write(Student("name",12)), "student2" -> write(Student("name2",13)))
//{"student1":"{\"name\":\"name\",\"age\":12}","student2":"{\"name\":\"name2\",\"age\":13}"}

If mean then [key:String]: StudentμPickleMap[String, Student]似乎支持這種開箱即用

case class Example(
  m: Map[String, Student],
  _logOp: Option[Boolean] = Some(false),
  queryName: String
)
object Example {
  implicit val rw: ReadWriter[Example] = macroRW
}

write(Example(
  Map("student1" -> Student("name",12), "student2" -> Student("name2",13)),
  Some(true),
  "abc"
))
//{"m":{"student1":{"name":"name","age":12},"student2":{"name":"name2","age":13}},"_logOp":[true],"queryName":"abc"}

它不應該嵌套在m

您可以使用自定義編解碼器（pickler）來實作這一點

import upickle.default.{ReadWriter, macroRW, readwriter, transform, write, read}
import scala.collection.mutable

case class Example(
  m: Map[String, Student],
  _logOp: Option[Boolean] = Some(false),
  queryName: String
)
object Example {
  implicit val rw: ReadWriter[Example] = {
    val standardExampleRW = macroRW[Example]
    readwriter[ujson.Value].bimap[Example](
      example => transform[Example](example)(standardExampleRW).to[ujson.Value] match {
        case ujson.Obj(standardMap) =>
          val newMap = mutable.LinkedHashMap.empty[String, ujson.Value]
          standardMap.remove("m")
          newMap.addAll(example.m.map { case (str, stud) => str -> transform[Student](stud).to[ujson.Value]})
            .addAll(standardMap)
          ujson.Obj(newMap)
      },
      // if you don't need a reversed transform i.e. from a json to an Example then you can omit this part
      // _ => ??? 
      {
        case ujson.Obj(newMap) =>
          val logOpJson = newMap.remove("_logOp")
          val logOp = logOpJson.map(transform[ujson.Value](_).to[Option[Boolean]])
          val queryNameJson = newMap.remove("queryName")
          val queryName = queryNameJson.map(transform[ujson.Value](_).to[String]).getOrElse("")
          val m = newMap.map { case (str, json) => str -> transform[ujson.Value](json).to[Student] }.toMap
          logOp.map(Example(m, _, queryName)).getOrElse(Example(m, queryName = queryName))
      }
    )
  }
}

write(Example(
  Map("student1" -> Student("name",12), "student2" -> Student("name2",13)),
  Some(true),
  "abc"
))
//{"student1":{"name":"name","age":12},"student2":{"name":"name2","age":13},"_logOp":[true],"queryName":"abc"}

read[Example](
  """{"student1":{"name":"name","age":12},"student2":{"name":"name2","age":13},"_logOp":[true],"queryName":"abc"}"""
)
//Example(Map(student1 -> Student(name,12), student2 -> Student(name2,13)),Some(true),abc)

因此，基本上您可以在 Scala 中生成案例類，但不需要序列化為 json 格式。

標籤：json斯卡拉类型类隐含的泡菜

上一篇：播放框架重定向到另一臺主機

下一篇：通過計算字串的長度來操作字串時，如何獲得更多功能性的基于Scala的代碼？