Scala extract values into array for multiple case classes

Question

I'm new to Scala and have had a look around at similar questions, but am not certain they're the same as my question - apologies if I'm wrong.

Essentially, I am unsure how to refactor this code

case class ModelX(a: Int, b: Int)

case class ModelY(b: Int, c: Int)

case class ModelZ(a: Int, c: Int)


def extract_x(e: ModelX): Array[Any] = e.productIterator.map {

  case op: Option[_] => op.getOrElse(null)
  case v => v

}.toArray


def extract_y(e: ModelY): Array[Any] = e.productIterator.map {

  case op: Option[_] => op.getOrElse(null)
  case v => v

}.toArray


def extract_z(e: ModelZ): Array[Any] = e.productIterator.map {

  case op: Option[_] => op.getOrElse(null)
  case v => v

}.toArray

for any number of models (as I have have more than 3). The reason I am doing this, is that I can extract a row from Cassandra into one of these models, then I need to pass it to an Array[Any] as I have serialisation methods available to me after this point, and can work with the returned values more comfortably in my language of choice.

I have tried defining a base class that ModelX|Y|Z extend, such that I could just apply extract on the base class, but productIterator is not available to the base class. If that was a bad explanation, what I tried/wanted to do was this:

class BaseModel()

case class ModelX(a: Int, b: Int) extends BaseModel

case class ModelY(b: Int, c: Int) extends BaseModel

case class ModelZ(a: Int, c: Int) extends BaseModel


def extract(e: BaseModel): Array[Any] = e.productIterator.map {

  case op: Option[_] => op.getOrElse(null)
  case v => v

}.toArray

I'm very new to Scala, so I imagine I've missed something obvious. Any help here would be appreciated.

Akhil

Alexey Romanov · Accepted Answer · 2017-09-04 13:32:19Z

2

productIterator is defined on scala.Product, which all case classes extend, so you can just write

def extract(e: Product): Array[Any] = ...

It may or may not be a problem that you can call this method on all Products, not just your models. If you want to avoid this, just make BaseModel in your last snippet extend Product:

abstract class BaseModel() extends Product

Look up abstract classes in case you aren't familiar with this term.

edited Sep 4, 2017 at 13:32

answered Sep 4, 2017 at 11:29

Alexey Romanov

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