StopKran StopKran - 3 months ago 41
Scala Question

How to use Future inside DBIOAction composition in slick 3?

Slick 3 offers DBIOAction composition by using flatMap method. Also, we can do some calculations in back-end between two DBIOActions. That's works fine in most cases, but what I should do when calculations result is in the monad like Future? There is code with blocking way:

val fooQuery = TableQuery[FooTable]
val barQuery = TableQuery[BarTable]

def requestService(content: Iterable[String]): Future[Iterable[Long]] = ???

def modify(ids: Iterable[Long], change: String) = {

val query = fooQuery.filter( inSet ids).result.flatMap{ fooSeq =>
val content =
val requestServiceFuture = requestService(content)

val serviceResult = Await.result(requestServiceFuture, 1.minute)
barQuery.filter( inSet serviceResult).delete //or other action

Is there way to perform this code asynchronously, without Await?


You can create DBIO from Future using DBIOAction.from and then compose with other DBIOs using flatMap

val query = for {
    fooSeq <- fooQuery.filter( inSet ids).result
    content =
    serviceResult <- DBIOAction.from(requestService(content))
    result <- barQuery.filter( inSet serviceResult).delete
} yield result$