Minimize Boiler Plate code when writing Slick 3.0 Queries - scala

Question

I wrote my first data access object in slick 3.0. it works but I found a lot of repetitive code in my code
class Items(tag: Tag) extends Table[Item](tag, "ITEMS") {
def id = column[Long]("ITEMS_ID", O.PrimaryKey, O.AutoInc)
def name = column[String]("ITEMS_NAME")
def price = column[Double]("ITEMS_PRICE")
def * = (id, name, price) <> ((Item.apply _).tupled, Item.unapply _)
}
object Shop extends Shop{
val items = TableQuery[Items]
val db = Database.forConfig("h2mem1")
def create(name: String, price: Double) : Int = {
val action = items ++= Seq(Item(0, name, price))
val future1 = db.run(action)
val future2 = future1 map {result =>
result map {x => x}
}
Await.result(future2, Duration.Inf).getOrElse(0)
}
def list() : Seq[Item] = {
val action = items.result
val future = db.run(action)
val future2 = future map {result =>
result map {x => x}
}
Await.result(future2, Duration.Inf)
}
def get(id: Long) : Option[Item] = {
val query = items.filter(_.id === id).result
val future1 = db.run(query)
val future2 = future1 map {result =>
result.map {x => x}
}
Await.result(future2, Duration.Inf).headOption
}
def delete(id: Long) : Int = {
val query = items.filter(_.id === id).delete
val future1 = db.run(query)
val future2 = future1 map {result =>
result
}
Await.result(future2, Duration.Inf)
}
def update(item: Item) : Int = {
val query = items.filter(_.id === item.id).update(item)
val future1 = db.run(query)
val future2 = future1 map {result => result}
Await.result(future2, Duration.Inf)
}
def createItemsTable() : Boolean = {
if (!checkTable("ITEMS")) {
val action = items.schema.create
val future1 = db.run(action)
future1 map {x => x}
true
} else false
//Await.result(future2, Duration.Inf)
}
def checkTable(tableName: String) : Boolean = {
val action = MTable.getTables
val future1 = db.run(action)
val future2 = future1 map {result =>
result map {x => x.name.name}
}
val retVal = Await.result(future2, Duration.Inf)
retVal.exists(x => x == tableName)
}
}
this works, but i hate the fact that I am writing this piece of code again and again
val future1 = db.run(query)
val future2 = future1 map {result => result}
Await.result(future2, Duration.Inf)
and
val future1 = db.run(query)
val future2 = future1 map {result =>
result.map {x => x}
}
Await.result(future2, Duration.Inf)
I want to know if there is a generic and safe way of avoiding the repeated use of these lines in every function.

Answer 1

You can define a generic function like
def runAction[R, Q](action: DBIOAction[R, NoStream, Nothing])(f: R => Q): Q = {
val future1 = db.run(action)
val future2 = future1 map { r: R =>
f(r)
}
Await.result(future2, Duration.Inf)
}
and use it like
def create(name: String, price: Double): Int = {
val action = items ++= Seq(Item(0, name, price))
runAction(action)(_.map(x => x)).getOrElse(0)
}