Circe: Json object to Custom Object - arrays

Question

I've go this json node
...
"businessKeys": [
"product://color?product_code",
"product://?code"
]
...
after a sequence of computation I have a Json istance but I'm not able to understand how I can transform that object into a List of my object. So Json (istance) to List[MyClass].
MyClass(root: ParameterType, children: List[ParameterType] = List.empty)
ParameterType(parameter: String)
I have a method that transform a String into a MyClass istance, so I need to decode Json into List[String] and then call my function or there is a direct method?
Thanks

Answer 1

You need implement our own io.circe.Decoder, in your case it can be converted from decoder for string.
Please, find some example code below:
import io.circe._
import io.circe.generic.auto._
object CirceExample {
class ParameterType(parameter: String) {
override def toString: String = parameter
}
class MyClass(root: ParameterType, children: List[ParameterType] = List.empty) {
override def toString: String = s"MyClass($root, $children)"
}
object MyClass {
/**
* Parsing logic from string goes here, for sake of example, it just returns empty result
*/
def parse(product: String): Either[String, MyClass] = {
Right(new MyClass(new ParameterType("example")))
}
// This is what need - just declare own decoder, so the rest of circe infrastructure can use it to parse json to your own class.
implicit val decoder: Decoder[MyClass] = Decoder[String].emap(parse)
}
case class BusinessKeys(businessKeys: List[MyClass])
def main(args: Array[String]): Unit = {
val json = "{ \"businessKeys\": [\n \"product://color?product_code\",\n \"product://?code\"\n ] }"
println(parser.parse(json).map(_.as[BusinessKeys]))
}
}
Which in my case produced next output:
Right(Right(BusinessKeys(List(MyClass(example, List()), MyClass(example, List())))))
Hope this will help you!