Let's say I have a case class X(id: Int, name: String, age: Int) and some function (in my case, withUniqueGeneratedKeys in doobie) that returns X. If I have already defined X I am good.
But in my case the core data structure is something like:
case class XData(name: String, age: Int)
case class MaterializedX(id: Int, element: XData)
And of course I could write a line like case class X(id: Int, name: String, age: Int) to create X but it would be duplication of logic - whenever something about XData changes, I'd have to change the code for X as well. Intuitively, it feels like there should be a way to derive X from XData and MaterializedX. This transformation might mean some code, but it would save me lots of future work because I have many item types beyond X.
How could this be done? Happy to hear other approaches.
I am using Scala 3.1.2 in case this matters. Thank you!
Edit: Changed title per helpful comment, to make this question easier to understand.
CodePudding user response：
I think you should be more clear about the question, I mean what title says is almost completely different from your question description (and what you might be actually looking for). Anyway, in my assumptions, what you need is probably a custom Read[MaterializedX] and Write[MaterializedX], as follows:
implicit val pointMaterializedX: Read[MaterializedX] =
Read[(Int, String, Int)]
.map {
case (id, name, age) => MaterializedX(id, XData(name, age))
}
implicit val pointWrite: Write[MaterializedX] =
Write[(Int, String, Int)]
.contramap { materializedX =>
(materializedX.id, materializedX.element.name, materializedX.element.age)
}
CodePudding user response：
This works out of the box with doobie. Nested case classes get flattened into one row. The following code compiles without defining any custom decoders.
case class XData(name: String, age: Int)
case class MaterializedX(id: Int, element: XData)
implicitly[doobie.Read[MaterializedX]]
implicitly[doobie.Write[MaterializedX]]