Scala - How to concatenate List and Option values after joining two RDDs?

Question

I have two RDDs that I want to join - salesfromSource1: RDD[(String, List[Sale])] and filteredSales: RDD[(String, Sale)]

Since I want to perform a left join I've tried the following:

val joinedSales: RDD[(String, (List[Sale], Option[Sale]))] = salesfromSource1.leftOuterJoin(filteredSales)

But how do I concatenate the values so that as a result I get RDD[(String, List[InvocaCall])] ?

I expected to achieve this with .mapValues(_._1 ::: _._2)

However I'm getting a type mismatch compiler highlighting (expected (List[Sale], Option[Sale]) => NotinferedU, actual: (Any, Any) => Any)

Answer 1

For example like this:

.mapValues {
   case (x, None) => x
   case (x, Some(y)) => x :: y
}

or

.mapValues { x =>
  x._2.map(y => x._1 :: y).getOrElse(x._1)
}