Create list of case class instances

Question

I have 3 vals, each of type Array[String]

they are all equal in length

val1.length == val2.length // true

Next, I created a case class as following:

case class resource(name: String, count: Int, location: String)

I want to create a list, a List[resource] such that each object of this list is created from the corresponding elements of the vals, i.e, val1, val2, val3

Something like this:

val newList: List[resource] = (val1(0), val2(0).toInt, val3(0)),
                              (val1(1), val2(1).toInt, val3(1)),
                              ...
                              (val1(val1.length), val2(val2.length).toInt, val3(val3.length)

I'm not sure how to proceed. Do I use flatMap, foreach, for-loops, or something else?

The idea is to create this abovementioned newList and compare it to the result obtained from a SQL database using doobie.

val comparator = sql"sql statment".query[resource]
comparator.to[List].transact(xa).unsafeRunSync()

Answer 1

You can zip your arrays, which combines the corresponding elements of the zipped sequences into tuples, and them map the resource.apply method over the combined sequence:

val val1: Array[String] = Array("name 1", "name 2", "name 3")
val val2: Array[String] = Array("1", "2", "3")
val val3: Array[String] = Array("loc 1", "loc 2", "loc 3")

scala> (val1, val2.map(_.toInt), val3).zipped.map(resource)
res1: Array[resource] = Array(resource(name 1,1,loc 1), resource(name 2,2,loc 2), resource(name 3,3,loc 3))

You can then convert this Array to List if needed:

scala> (val1, val2.map(_.toInt), val3).zipped.map(resource).toList
res2: List[resource] = List(resource(name 1,1,loc 1), resource(name 2,2,loc 2), resource(name 3,3,loc 3))