Is that possible to make semiauto decoders consider default values for case class fields?
The following code will fail with:
Left(DecodingFailure(Attempt to decode value on failed cursor, List(DownField(isActive))))
I thought circe would consider the default value for the case class field isActive
case class Person(
id: Option[Int] = None,
name: String,
isActive: Boolean = true
)
implicit val personJsonDecoder: Decoder[Person] = deriveDecoder
val rawJson = """
{
"name": "Geovanny Junio"
}
"""
val r = for {
j <- parse(rawJson)
p <- j.as[Person]
} yield p
println(r)
Yes, but you'll need circe-generic-extras:
import io.circe.Decoder
import io.circe.generic.extras.Configuration
import io.circe.generic.extras.semiauto.deriveDecoder
case class Person(
id: Option[Int] = None,
name: String,
isActive: Boolean = true
)
object Person {
implicit val personConfig: Configuration =
Configuration.default.withDefaults
implicit val personJsonDecoder: Decoder[Person] = deriveDecoder
}
And then:
scala> io.circe.jawn.decode[Person]("""{"name": "Geovanny Junio"}""")
res0: Either[io.circe.Error,Person] = Right(Person(None,Geovanny Junio,true))
I've been intending to add this functionality to circe-derivation, but haven't had time, so circe-generic-extras is the only way to make it work for now (short of writing your own decoder).
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