Scala Strange Error with Partial Functions -


i have following piece of code fails compilation strange reason!

def createnewpowerplant = action.async(parse.tolerantjson) { request =>     request.body.validate[powerplantconfig].fold(       errors => {         future.successful(           badrequest(json.obj("message" -> s"invalid powerplantconfig $errors"))         )       },       success => { // fails here!!         dbservice.newpowerplant(topowerplantrow(success)).recover {           case nonfatal(ex) =>             future.successful { unprocessableentity(               json.obj("message" -> s"could not create new powerplant because of ${ex.getmessage}")             ) }         }         future.successful { ok("") }       }     )   }

and see reason:

controller.scala:103: type inferred `any`; may indicate programming error. [error]       success => { [error]                  ^ [error] 1 error found [error] (compile:compileincremental) compilation failed [error] total time: 16 s, completed aug 21, 2017 9:46:30

any ideas why error happens? i'm sure has got compiler have similar code in controller compiles!

you have "-xfatal-warnings" in build.sbt. makes compiler throw compilation error in regular case warning. check i've commented "-xfatal-warnings". sbt clean compile gives this:

alex@positron /ssd2/projects/powerplantproblem/plant-simulator $ sbt clean compile [info] loading project definition /ssd2/projects/powerplantproblem/plant-simulator/project [info] updating {file:/ssd2/projects/powerplantproblem/plant-simulator/project/}plant-simulator-build... waiting lock on /home/alex/.ivy2/.sbt.ivy.lock available... [info] resolving org.fusesource.jansi#jansi;1.4 ... [info] done updating. [info] set current project plant-simulator (in build file:/ssd2/projects/powerplantproblem/plant-simulator/) [success] total time: 0 s, completed aug 21, 2017 3:39:57 pm [info] updating {file:/ssd2/projects/powerplantproblem/plant-simulator/}root... [info] resolving jline#jline;2.14.3 ... [info] done updating. [info] compiling 31 scala sources , 2 java sources /ssd2/projects/powerplantproblem/plant-simulator/target/scala-2.11/classes... [warn] /ssd2/projects/powerplantproblem/plant-simulator/app/com/inland24/plantsim/controllers/powerplantcontroller.scala:102: type inferred `any`; may indicate programming error. [warn]           case some(row) => dbservice.newpowerplant(row) recoverwith{ [warn]                ^ [warn] 1 warning found [success] total time: 23 s, completed aug 21, 2017 3:40:20 pm alex@positron /ssd2/projects/powerplantproblem/plant-simulator $

this means suggestion true. either disable "-xfatal-warnings" or make code satisfy more strict requirements brings on.

now in order understand warning itself, take @ signature of recoverwith method:

def recoverwith[u >: t](pf: partialfunction[throwable, future[u]])(implicit executor: executioncontext): future[u]

in case t int. common ancestor of int , future[result] any of course. can make compilable "-xfatal-warnings" inserting int value here:

case some(row) => dbservice.newpowerplant(row) recoverwith{   case ex: exception => future.successful{     unprocessableentity(       json.obj("message" -> s"could not create new powerplant because of ${ex.getmessage}")     )     5   } }

the warning makes sense here because code not clean: trying recover problem inserting row db (e.g. db server down) returning unprocessableentity http status not make sense, taking account override intention after future.successful { ok("") }.

hope helps.


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