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我正在关注以下示例https://github.com/leon/play-salat/tree/master/sample。在我的数据模型中，我有列表，并试图采用该模型。隐式json读取和列表写入
我得到以下编译错误：
[error] /home/malte/workspace/bdt/app/models/Ballot.scala:26: No Json deserializer found for type List[models.Position]. Try to implement an implicit Writes or Format for this type.
[error] "positions" -> b.positions,
[error] ^
[error] /home/malte/workspace/bdt/app/models/Ballot.scala:33: No Json deserializer found for type List[models.Position]. Try to implement an implicit Reads or Format for this type.
[error] (__ \ 'values).read[List[Position]]).map { l => l.getOrElse(Nil) } ~
对于类型“位置”我有隐含的读取和写入，但如何使其成为列表[位置]？我的隐写和读：
implicit val ballotJsonWrite = new Writes[Ballot] {
def writes(b: Ballot): JsValue = {
Json.obj(
"positions" -> b.positions,
"title" -> b.title)
}
}
implicit val ballotJsonRead = (
(__ \ 'positions).readNullable(
(__ \ 'values).read[List[Position]]).map { l => l.getOrElse(Nil) } ~
(__ \ 'title).read[String])(Ballot.apply _)
对于我跟着Create implicit json read for List collection which might be missing from input json读，但我得到了上述的错误。