[英]How to Decode a Generic Case Class with semiautomatic in Circe in Scala 3
[英]How to Decode a Generic Case Class with semiautomatic in Circe
我有以下案例類:
case class QueryResult[T: Decoder](data: T)
它適用於自動推導。
但是我無法解決它以進行半自動推導。
這是我的測試用例:
//import io.circe.generic.auto._ // with this it works
import io.circe.derivation._
case class Name(name: String)
case class QueryResult[T: Decoder](data: T)
implicit val nameDer = deriveDecoder[Name]
implicit def result[T: Decoder] = deriveDecoder[QueryResult[T]] // this does not work
這給了我:
Error:(16, 50) No method evidence$1 in pme123.graphql.client.QueryResult[T] (this is probably because a constructor parameter isn't a val)
implicit def result[T: Decoder] = deriveDecoder[QueryResult[T]]
你用的是哪個版本的circe? 在 0.12.3 我必須使用import io.circe.generic.semiauto._
並且以下對我import io.circe.generic.semiauto._
:
case class Name(name: String)
case class QueryResult[T: Decoder](data: T)
implicit val nameDer = deriveDecoder[Name]
implicit def result[T: Decoder] = deriveDecoder[QueryResult[T]]
val json = """{"data": {"name": "foo"}}"""
decode[QueryResult[Name]](json) // Right(QueryResult(Name(foo)))
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