[英]Scala Jackson object mapper setting null instead of default values in case class
[英]Is that possible to make semiauto decoders consider default values for case class fields?
是否可以使半自動解碼器考慮案例類字段的默認值?
以下代碼將失敗並顯示:
Left(DecodingFailure(Attempt to decode value on failed cursor, List(DownField(isActive))))
我認為馬戲團會考慮案例類字段的默認值為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)
是的,但是您需要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
}
接着:
scala> io.circe.jawn.decode[Person]("""{"name": "Geovanny Junio"}""")
res0: Either[io.circe.Error,Person] = Right(Person(None,Geovanny Junio,true))
我一直打算將此功能添加到circe-derivation中,但還沒有時間,因此circe-generic-extras是目前使其工作的唯一方法(缺少編寫自己的解碼器的功能)。
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