使用play json写入时转换类型 [英] Converting types when using play json writes

问题描述

此问题之后应用转换在应用于类之前先播放框架json元素

我有一个Date对象，我想以特定格式将其写入json中的字符串.

I have a Date object which I want to be written to a string in json in a specific format.

implicit val tokenWrites: Writes[Token] = (
  (JsPath \ "creation_date").write[Date] and
  (JsPath \ "expires").writeNullable[Date]
)(unlift(Token.unapply))

我想被json化为

"creation_date": "2014-05-22T08:05:57.556385+00:00"

要将字符串转换为我使用过的日期:

To convert the string to a Date I have used:

def strToDate(string2: String): Date = {
  val df2 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
  df2.parse(string2);
}

然后将其映射到读取中，但这似乎无法通过写操作实现

And then mapped in the reads, but this doesn't seem to be possible with a write

推荐答案

按照write

def write[T](implicit w: Writes[T])

您可以创建自己的Writes[T]并使用它.

you can create own Writes[T] and use it.

例如

object dateWrite extends Writes[Date] {
  override def writes(o: Date): JsValue = JsString("some formatted date")
}

会将o:Date写入JsString("some formatted date")(可以使用自己的格式:Date => JsValue)，然后在write中使用自己的Writes[T]:

will write o:Date to JsString("some formatted date") (you can use own format: Date => JsValue), and then use own Writes[T] in write:

implicit val tokenWrites: Writes[Token] = (
  (JsPath \ "creation_date").write[Date](dateWrite) and
    (JsPath \ "expires").writeNullable[Date](dateWrite)
  ) (unlift(Token.unapply))

结果

tokenWrites.writes(Token(new Date(), Some(new Date())))

将是

res1: play.api.libs.json.JsValue = {"creation_date":"some formatted date","expires":"some formatted date"}

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