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copied!<p>Play 2.1 JSON API does not provide a serializer for the Type <code>Map[String, Object]</code>.</p> <p>Define <code>case class</code> and <code>Format</code> for the specific type instead of <code>Map[String, Object]</code>:</p> <pre><code>// { "val1" : "xxx", "val2" : ["a", "b", "c"] } case class Hoge(val1: String, val2: List[String]) implicit val hogeFormat = Json.format[Hoge] </code></pre> <p>If you don't want to create case class. The following code provides JSON serializer/deserializer for Map[String, Object]:</p> <pre><code>implicit val objectMapFormat = new Format[Map[String, Object]] { def writes(map: Map[String, Object]): JsValue = Json.obj( "val1" -> map("val1").asInstanceOf[String], "val2" -> map("val2").asInstanceOf[List[String]] ) def reads(jv: JsValue): JsResult[Map[String, Object]] = JsSuccess(Map("val1" -> (jv \ "val1").as[String], "val2" -> (jv \ "val2").as[List[String]])) } </code></pre> <hr> <p>Jackson doesn't know how to deserialize the Scala collection class <code>scala.collection.immutable.Map</code>, because it doesn't implement any of the Java collection interfaces.</p> <p>You can either deserialize to a Java collection:</p> <pre><code>val mapData = mapper.readValue(jsonContent, classOf[java.util.Map[String,String]]) </code></pre> <p>or add the Scala module to the mapper:</p> <pre><code>mapper.registerModule(DefaultScalaModule) val mapData = mapper.readValue(jsonContent, classOf[Map[String,String]]) </code></pre> <p>or <strong>you can also try like this</strong> </p> <pre><code>import play.api.libs.json._ val a1=Map("val1"->"a", "val2"->"b") Json.toJSon(a1) </code></pre> <p>Because a1 is just <code>Map[String,String]</code> that works OK.</p> <p>But if I have something more complex like where I have <code>Map[String,Object]</code>, that doesn't work:</p> <pre><code> val a = Map("val1" -> "xxx", "val2"-> List("a", "b", "c")) Json.toJSon(a1) >>> error: No Json deserializer found for type scala.collection.immutable.Map[String,Object] </code></pre> <p>I found that I can do something like the following:</p> <pre><code>val a2 = Map("val1" -> Json.toJson("a"), "val2" -> Json.toJson(List("a", "b", "c"))) Json.toJson(a2) </code></pre> <p>And that works.`</p>

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