[英]Scala Play Json Format for Map[Locale, String]
I have objects of type 我有类型的对象
Map[java.util.Locale, String]
How can I make Json Writes / Reads for this? 我该如何让Json进行读写操作? I have looked at a couple other questions , but couldn't come up with a solution myself.
我看了其他 几个 问题 ,但本人无法解决。 I got (but not tested yet) something for Locale
我有(但尚未测试)适用于Locale的内容
implicit val localeReads: Reads[Locale] = new Reads[Locale] {
def reads(json: JsValue): JsResult[Locale] =
json match {
case JsString(langString) => JsSuccess(new Locale(langString))
case _ => JsError("Locale Language String Expected")
}
}
implicit val localeWrites: Writes[Locale] = new Writes[Locale] {
def writes(locale: Locale) = JsString(locale.toString)
}
How can I then use this in 然后我该如何使用
implicit val myMapReads: Reads[Map[Locale, String]] = ???
implicit val myMapWrites: Writes[Map[Locale, String]] = ???
? ?
This should work: 这应该工作:
implicit val localeReads: Reads[Locale] = new Reads[Locale] {
def reads(json: JsValue): JsResult[Locale] =
json match {
case JsString(langString) => JsSuccess(new Locale(langString))
case _ => JsError("Locale Language String Expected")
}
}
implicit val localeWrites: Writes[Locale] = new Writes[Locale] {
def writes(locale: Locale) = JsString(locale.toString)
}
implicit val myMapWrites: Writes[Map[Locale, String]] = new Writes[Map[Locale, String]] {
override def writes(o: Map[Locale, String]): JsValue = Json.toJson(o)
}
implicit val myMapRead: Reads[Map[Locale, String]] = new Reads[Map[Locale, String]] {
override def reads(json: JsValue): JsResult[Map[Locale, String]] = JsSuccess {
json.as[JsObject].value.map {
case (k, v) => (new Locale(k), v.as[String])
}.toMap
}
}
Basically play already knows how to convert a Locale
to json because of the Writes
you provided so simply calling toJson
will work. 由于您提供了
Writes
,因此play基本上已经知道如何将Locale
转换为json,因此只需调用toJson
即可。
For the Reads
it's a bit more complex and you have to do a mapping, .value
returns a Map[String, JsValue]
where the first represents the Locale
object and the second a simple string so calling as[String]
will already give you what you want. 对于
Reads
来说,它有点复杂,您必须进行映射, .value
返回Map[String, JsValue]
,其中第一个表示Locale
对象,第二个表示简单字符串,因此调用as[String]
已经可以为您提供你要。
Note that I've wrapped everything in a JsSuccess
but you may assume that the json you got cannot be converted to JsObject
, apply a try/catch, and decide wether you want to return success or failure. 请注意,我已经将所有内容包装在
JsSuccess
但是您可能会假设无法将获得的json转换为JsObject
,无法进行try / catch并决定是否要返回成功或失败。
Here's a function that will create a Format[K,V]
for you if K
serialises to a JsString
: 如果
K
序列JsString
,则此函数将为您创建Format[K,V]
:
/** Play Json only supports Map[String,V]. This function creates a format for Map[K,V]. The type K should produce a JsString.
* Otherwise the serialisation will fail. Which should be good enough since in valid json keys can only be strings.
*/
def mapFormat[K, V](implicit fk: Format[K], fv: Format[V]): Format[Map[K, V]] =
new OFormat[Map[K, V]] {
override def writes(o: Map[K, V]): JsObject = {
val stringMap = o.map { case (k, v) => (Json.toJson[K](k).as[JsString].value, v) }
Json.toJson(stringMap).as[JsObject]
}
override def reads(json: JsValue): JsResult[Map[K, V]] = {
for {
stringMap <- Json.fromJson[Map[String, V]](json)
_ <- Json.fromJson[Set[K]](Json.toJson(stringMap.keySet))
} yield stringMap.map { case (k, v) => (Json.fromJson[K](JsString(k)).get, v) }
}
}
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