There are 2 different scenarios I'm dealing with: one where I can successfully decode a single user, and another where decoding a list of users fails:
import User._
import io.circe._
import io.circe.syntax._
import io.circe.parser.decode
class UserSuite extends munit.FunSuite:
test("List of users can be decoded") {
val json = """|{
| "data" : [
| {
| "id" : "someId",
| "name" : "someName",
| "username" : "someusername"
| },
| {
| "id" : "someId",
| "name" : "someName",
| "username" : "someusername"
| }
| ]
|}""".stripMargin
println(decode[List[User]](json))
}
test("user can be decoded") {
val json = """|{
| "data" : {
| "id" : "someId",
| "name" : "someName",
| "username" : "someusername"
| }
|}""".stripMargin
println(decode[User](json))
}
The failed attempt results in this error message:
Left(DecodingFailure(List, List(DownField(data))))
This is puzzling because both the JSON structure and decoders (defined below) are identical.
final case class User(
id: String,
name: String,
username: String
)
object User:
given Decoder[List[User]] =
deriveDecoder[List[User]].prepare(_.downField("data"))
given Decoder[User] =
deriveDecoder[User].prepare(_.downField("data"))
I thought everything was set up correctly based on insights from Travis' older reply, but it seems to hit a snag.
Could this be a bug? Am I missing something?
Just for context, this is using Scala 3.2.0 and circe 0.14.1