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copied!<p>Play 2.1 JSON API does not provide a serializer for the Type <code>Map[String, Ojbect]</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> <h2>More dynamically</h2> <pre><code>import play.api.libs.json._ import play.api.libs.json.Reads._ import play.api.libs.json.Json.JsValueWrapper implicit val objectMapFormat = new Format[Map[String, Object]] { def writes(map: Map[String, Object]): JsValue = Json.obj(map.map{case (s, o) => val ret:(String, JsValueWrapper) = o match { case _:String => s -> JsString(o.asInstanceOf[String]) case _ => s -> JsArray(o.asInstanceOf[List[String]].map(JsString(_))) } ret }.toSeq:_*) def reads(jv: JsValue): JsResult[Map[String, Object]] = JsSuccess(jv.as[Map[String, JsValue]].map{case (k, v) => k -> (v match { case s:JsString => s.as[String] case l => l.as[List[String]] }) }) } </code></pre> <p>Sample code:</p> <pre><code> val jv = Json.toJson(Map("val1" -> "xxx", "val2" -> List("a", "b", "c"), "val3" -> "sss", "val4" -> List("d", "e", "f"))) println(jv) val jr = Json.fromJson[Map[String, Object]](jv) println(jr.get) </code></pre> <p>The output:</p> <pre><code>> {"val1":"xxx","val2":["a","b","c"],"val3":"sss","val4":["d","e","f"]} > Map(val1 -> xxx, val2 -> List(a, b, c), val3 -> sss, val4 -> List(d, e, f)) </code></pre>

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