json – 如何将akka http请求实体unmarshall作为字符串？

path("mypath") {

  post {
    decodeRequest {
      entity(as[String]) {jsonStr => //could not find implicit value for...FromRequestUnmarshaller[String]
        complete {
          val json: JsObject = Json.parse(jsonStr).as[JsObject]
          val jsObjectFuture: Future[JsObject] = MyDatabase.addListItem(json)
          jsObjectFuture.map(_.as[String])
        }
      }          
    }
  }
}

您的代码应该是可以的,只要你有适当的范围.如果您在范围内有一个隐式FlowMaterializer,那么事情应该像编译显示的代码一样工作：

import akka.http.scaladsl.server.Route
import akka.actor.ActorSystem
import akka.stream.ActorFlowMaterializer
import akka.http.scaladsl.model.StatusCodes._
import akka.http.scaladsl.server.Directives._
import akka.stream.FlowMaterializer

implicit val system = ActorSystem("test")
implicit val mater = ActorFlowMaterializer()

val routes:Route = {
  post{
    decodeRequest{
      entity(as[String]){ str =>
        complete(OK,str) 
      }
    }
  }    
}

如果你想要进一步的进一步解决一个JsObject,那么你只需要一个隐含的Unmarshaller在范围内来处理这个转换,就像这样：

implicit val system = ActorSystem("test")
implicit val mater = ActorFlowMaterializer()

import akka.http.scaladsl.unmarshalling.Unmarshaller
import akka.http.scaladsl.model.HttpEntity

implicit val um:Unmarshaller[HttpEntity,JsObject] = {
  Unmarshaller.byteStringUnmarshaller.mapWithCharset { (data,charset) =>
    Json.parse(data.toArray).as[JsObject]
  }    
}  

val routes:Route = {
  post{
    decodeRequest{
      entity(as[String]){ str =>
        complete(OK,str) 
      }
    }
  } ~
  (post & path("/foo/baz") & entity(as[JsObject])){ baz =>
    complete(OK,baz.toString)
  }    
}