How to break REST controller that return Action in Scala/Play framework

问题

I have a controller that run some code, I wrap some code in try/catch and wish to break the controller run during catch and return the error.
It does not return, How can i wrap my response in action function as required ?

Sample:

def updateProduct(productId:String,lang: String, t: String) = Action {
request =>
  request.body.asJson.map {
    json =>
    var product:Product=null 
    try
    {
      product = json.as[Product]
    }        
    catch
    {
        case ex: Exception => {
          val errorResponse:ErrorResponse[String] = ErrorResponse(ErrorCode.InvalidParameters, ex.getMessage, 500)
          return InternalServerError(Json.toJson(errorResponse)) //Does not stop,
          }
    }

    val response = productService.updateProduct(UpdateProductRequest(lang,t,productId,product))

    if (response.isError)
    {
        InternalServerError(Json.toJson(response))
    }
    else
    {
      Ok(Json.toJson(response))
    }}.getOrElse {
    Logger.warn("Bad json:" + request.body.asText.getOrElse("No data in body"))
      var errorResponse:ErrorResponse[String] = ErrorResponse(ErrorCode.GeneralError, "Error processing request", 500)
      errorResponse.addMessage("No data in body")
      Ok(Json.toJson(errorResponse))
      }
  }

I get error:

method updateProduct has return statement; needs result type

回答1:

When you use return you must, as it says, use an explicit return type. Scala will not infer it for you.

So, for example:

def fails(i: Int) = return (i+1)       // Doesn't compile
def works(i: Int): Int = return (i+1)  // Does

I am not sure what the common supertype of Ok and InternalServerError is, but that would be what you're after. If it's an unhelpful type like AnyRef (i.e. Object), using Either or the equivalent might be a good idea (i.e. Left(InternalServerError/*...*/), Right(Ok/*...*/)).

来源：https://stackoverflow.com/questions/22381645/how-to-break-rest-controller-that-return-action-in-scala-play-framework