How to create a class instance from slick query? - scala

Question

I am finding it difficult to figure out the best wy to create an instance of a class (a DTO class) which can be passed as json to the calling client.
I have the following class structure.
object Suppliers extends Table[(Int, String, String, String, String, String)]("SUPPLIERS") {
def id = column[Int]("SUP_ID", O.PrimaryKey) // This is the primary key column
def name = column[String]("SUP_NAME")
def street = column[String]("STREET")
def city = column[String]("CITY")
def state = column[String]("STATE")
def zip = column[String]("ZIP")
def * = id ~ name ~ street ~ city ~ state ~ zip
}
object Coffees extends Table[(Int,String, Double,Int, Int)]("COFFEES") {
def id = column[Int]("Id",O.PrimaryKey)
def name = column[String]("COF_NAME")
def price = column[Double]("PRICE")
def sales = column[Int]("SALES")
def total = column[Int]("TOTAL")
def * = id ~ name ~ price ~ sales ~ total
}
object CoffeeSuppliers extends Table[(Int,Int,Int)]("CoffeeSuppliers") {
def id = column[Int]("Id",O.PrimaryKey)
def supID = column[Int]("Sup_ID")
def coffeeID = column[Int]("Coffee_ID")
def supplier = foreignKey("SUP_FK", supID, Suppliers)(_.id)
def coffees = foreignKey("COF_FK", coffeeID,Coffees)(_.id)
def * = id ~ supID ~ coffeeID
}
I am using this simple join query to retrieve Supplier with id 101 and all the coffees he supplies.
val q3 = for {
((cs,c),s) <- CoffeeSuppliers innerJoin
Coffees on (_.coffeeID === _.id) innerJoin
Suppliers on (_._1.supID === _.id) if cs.supID === 101
} yield (cs,c,s)
The query is working fine and I am able to retrieve the data.
But, I want to construct a DTO class out of the query result. The Class structure is as fallows
case class CoffeeDTO(
id:Option[Int] = Some(0),
name:String[String] = "",
price:Double= 0.0
)
case class SupplierDTO (
id:Option[Int] = Some(0),
name:String = "",
coffees:List[CoffeeDTO] = Nil
)
How to create an instance of SupplierDTO and assign the values from the query result?

Answer 1

How about something like this:
q3.map{ case (cs,c,s) => ((s.id.?,s.name),(c.id.?,c.name,c.price)) } // remove not needed columns and make ids Options
.list // run query
.groupBy( _._1 ) // group by supplier
.map{ case (s,scPairs) => SupplierDTO( s._1, // map each group to a supplier with associated coffees
s._2,
scPairs.map(_._2) // map group of pairs to only coffee tuples
.map(CoffeeDTP.tupled) // create coffee objects
)}
.head // take just the one supplier out of the list