scala - In Slick 3.0, how to simplify nested `db.run`? -

i'm using slick 3.0, , following codes:

def registermember(newmember: teammember): future[long] = {    db.run(     teamprofiletable.filter(u => u.id === newmember.id).result.headoption   ).flatmap {     case none => future(-1)     case _ => db.run(       (teamprofiletable returning teamprofiletable.map(_.staffid)) += newmember.toteamrecord     )   } } 

this may ok. when there more layers of callback, codes may become hard read. tried simplify codes using for-expression or andthen.. due pattern matching part, can use flatmap implement this..

does have ideas how refactor this?

i think comprehension should okay here, need conditional handling of option in result of first future. should work (note did not compile check this):

def registermember(newmember: teammember): future[long] = {    for{     r1opt <- db.run(teamprofiletable.filter(u => u.id === newmember.id).result.headoption     r2 <- r1opt.fold(future.successful(-1l))(r1 => db.run((teamprofiletable returning teamprofiletable.map(_.staffid)) += newmember.toteamrecord)   } yield r2  } 

you can see on right side of fold have access result of first future if some (as r1).

i take step further , create separate methods steps of comprehension clean things up, so:

def registermember(newmember: teammember): future[long] = {   def findmember =      db.run(teamprofiletable.filter(u => u.id === newmember.id).result.headoption    def addmember(r1opt:option[teammember]) = {     r1opt.fold(future.successful(-1l)){r1 =>       db.run((teamprofiletable returning teamprofiletable.map(_.staffid)) +=          newmember.toteamrecord)     }   }    for{     r1opt <- findmember     r2 <- addmember(r1opt)   } yield r2  }