scala: play-framework future execution sequence within a single request - scala

Question

I am quite new with functional programming in scala and play-framework
I have an API request that need to add a chapter to a comic book authored by that particular user, thus I have to verify that the comic exist and belongs to that user. What complicates is the Future, Option etc and I can't make sure that the last command is executed last. Indeed, my problem occurs because the last command is executed before all my db access is completed
Here are the code, hope it is clear
def addchapter(): Action[AnyContent] = Action.async { implicit request =>
var hashMap: HashMap[String, JsValue] = HashMap()
var apiResult: ApiResult = ApiResult(
ReturnCode.COMIC_ADDCHAPTER.id,
ReturnCode.COMIC_ADDCHAPTER.toString(),
ReturnResult.RESULT_ERROR.toString(),
"init"
)
var fHashMap: Future[HashMap[String, JsValue]] = Future {
hashMap
}
try {
val oReq = request.body.asJson
val jsReq = oReq.getOrElse(JsString("null"))
val sessionid = (jsReq \
"sessionid").getOrElse(JsString("0")).as[String]
val comicid = (jsReq \
"comicid").getOrElse(JsString("comicid")).as[String]
val foUser = userRepo.getUserBySessionId(sessionid)
LogManager.DebugLog(this, "add chapter: " + sessionid + " => " +
comicid)
fHashMap = foUser.flatMap( oUser => {
oUser match {
case Some(user) => {
val foComic = comicRepo.getComicByComicId(comicid)
fHashMap = foComic.flatMap( oComic => {
oComic match {
case Some(comic) => {
LogManager.DebugLog(this, "about to add chapter")
val fTup = comicRepo.addChapterToComic(comic)
fHashMap = fTup.map( tuple => {
val wr = tuple._1
val mc = tuple._2
apiResult = ApiResult(
ReturnCode.COMIC_ADDCHAPTER.id,
ReturnCode.COMIC_ADDCHAPTER.toString(),
ReturnResult.RESULT_ERROR.toString(),
"successfully added chapter!"
)
val payloadcomic =
PayloadComicFactory.createWithComic(mc)
hashMap("apiresult") = Json.toJson(apiResult)
hashMap += "comic" -> Json.toJson(payloadcomic)
LogManager.DebugLog(this, "successfully added
chapter!")
hashMap
})
// return
fHashMap
}
case None => {
apiResult = ApiResult(
ReturnCode.COMIC_ADDCHAPTER.id,
ReturnCode.COMIC_ADDCHAPTER.toString(),
ReturnResult.RESULT_ERROR.toString(),
"comic not found"
)
hashMap("apiresult") = Json.toJson(apiResult)
Future { hashMap }
}
}
})
Future { hashMap }
}
case None => {
apiResult = ApiResult(
ReturnCode.COMIC_ADDCHAPTER.id,
ReturnCode.COMIC_ADDCHAPTER.toString(),
ReturnResult.RESULT_ERROR.toString(),
"unauthorized to add chapter to this comic"
)
hashMap("apiresult") = Json.toJson(apiResult)
Future { hashMap }
}
}
})
// I cannot put the return here, it is compile error saying that the return value is a Unit
// fHashMap.map( hashmap => {
// Ok(Json.toJson(hashmap))
// })
} catch {
case t: Throwable => {
LogManager.DebugException(this, "ex: ", t)
// I cannot put it here, it is compile error saying that the return value is Unit
// fHashMap.map( hashmap => {
// Ok(Json.toJson(hashmap))
// })
fHashMap
}
}
// I have to return here, but "return of the request" will be executed first before all my db access is completed, thus the ApiResult is still returning wrong state
LogManager.DebugLog(this, "return of the request")
fHashMap.map( hashmap => {
Ok(Json.toJson(hashmap))
})
}