Get all field values from subclasses in Scala - scala

Question

I have three class's
class A (
param1:Int,
param2:Int
)
class B (
param3:Int,
param4:Int
)
class C(
param1:A,
param2:B
)
And i need map between name of field to object, like
param1->1
param2->2
param3->3
param4->4
So i tired to did it as below but field its not type of Product
def func1(c: C): Map[String, Object] = {
var map = Map[String, Object]()
for (field <- c.getClass.getDeclaredFields) yield {
map ++ getFieldMap(field))
}
}
def getFieldMap(p: Product): Map[String, Object] = {
var values = p.productIterator
p.getClass.getDeclaredFields.map(_.getName -> {
values.next.asInstanceOf[AnyRef]
}).toMap
}

Answer 1

The are multiple problems with your code. The class A and class B do not implement the Product trait. You either have to do with Product manually and implement all the methods, or you declare them as case classes.
case class A (
val param1: Int,
val param2: Int
)
case class B (
val param3: Int,
val param4: Int
)
To ensure that Scala actually generates fields for the constructor parameters, add the val keyword in front.
Furthermore, you are passing the field (java.lang.reflect.Field), not it's value, which you have to get first.
def func1(c: C): Map[String, Object] = {
var map = Map[String, Object]()
for (field <- c.getClass.getDeclaredFields) yield {
field.setAccessible(true) // <- to avoid IllegalAccessException
map ++ getFieldMap(field.get(c)) // <- inserted .get(c)
}
}

Answer 2

If you can make your classes case classes, you can do it using shapeless:
import shapeless._
import shapeless.record._
case class A (param1:Int, param2:Int)
val a = A(12, 34)
val AGen = LabelledGeneric[A]
val map = AGen.to(a).toMap.map { case (k, v) => (k.name, v) }
println(map("param1")) // prints "12"