slick db.run is not called - scala

Question

I want to insert a record in database but the db.run is not called
my code looks like this
val insertQueryStep = processStepTemplates returning processStepTemplates.map(_.id) into ((processStep, id) => processStep.copy(id = Some(id)))
/**
* Generates a new ProcessStepTemplate
*
* #param step
* #return
*/
def addProcessStepTemplateToProcessTemplate(step: ProcessStepTemplatesModel, processId: Int): Future[Some[ProcessStepTemplatesModel]] = {
println("In DTO: " + step + ", processtemplate: " + processId)
//val p = processStepTemplates returning processStepTemplates.map(_.id) += step
val p = insertQueryStep += step
db.run(p).map(id => {
println("Die Query lautet: " + p)
println("Die erzeugte ID lautet: " + id)
//Update the foreign key
val q = for { p <- processStepTemplates if p.id == id } yield p.processtemplate
val updateAction = q.update(Some(processId))
db.run(updateAction).map(id => {
println("Der neue Prozesschritt lautet: " + step)
Some(step)
})
Some(step)
})
}
What could be a problem in this case?

Answer 1

You should compose your futures as monads (with flatMap). Because the inner future will not complete.
Try to change your code in the following way (see comments #1, #2):
def addProcessStepTemplateToProcessTemplate(step: ProcessStepTemplatesModel, processId: Int): Future[Some[ProcessStepTemplatesModel]] = {
println("In DTO: " + step + ", processtemplate: " + processId)
//val p = processStepTemplates returning processStepTemplates.map(_.id) += step
val p = insertQueryStep += step
db.run(p).flatMap(id => { // #1 change map to flatMap
println("Die Query lautet: " + p)
println("Die erzeugte ID lautet: " + id)
//Update the foreign key
val q = for { p <- processStepTemplates if p.id == id } yield p.processtemplate
val updateAction = q.update(Some(processId))
val innerFuture = db.run(updateAction).map(id => {
println("Der neue Prozesschritt lautet: " + step)
Some(step)
})
innerFuture // # 2 return inner future
})
}
Also use a logging for detecting another issues (connected with db-schema, queries, etc).