Type hint transformation for sealed hierarchies (#1093)

docs/configuration.md

@@ -80,6 +80,32 @@ banana.toJson
 apple.toJson
 ```
 
+Another way of changing type hint is using `@jsonHintNames` annotation on sealed class. It allows to apply transformation
+to all type hint values in hierarchy. Same transformations are provided as for `@jsonMemberNames` annotation.
+
+Here's an example:
+
+```scala mdoc
+import zio.json._
+
+@jsonHintNames(SnakeCase)
+sealed trait FruitKind
+
+case class GoodFruit(good: Boolean) extends FruitKind
+
+case class BadFruit(bad: Boolean) extends FruitKind
+
+object FruitKind {
+ implicit val encoder: JsonEncoder[FruitKind] =
+ DeriveJsonEncoder.gen[FruitKind]
+}
+
+val goodFruit: FruitKind = GoodFruit(true)
+val badFruit: FruitKind = BadFruit(true)
+
+goodFruit.toJson
+badFruit.toJson
+```
 ## jsonDiscriminator
 
 

zio-json-macros/shared/src/test/scala/zio/json/DeriveSpec.scala

@@ -31,13 +31,28 @@ object DeriveSpec extends ZIOSpecDefault {
  assert("""{"Child2":{}}""".fromJson[Parent])(isRight(equalTo(Child2()))) &&
  assert("""{"type":"Child1"}""".fromJson[Parent])(isLeft(equalTo("(invalid disambiguator)")))
  },
+ test("sum encoding with hint names") {
+ import examplesumhintnames._
+
+ assert("""{"child1":{}}""".fromJson[Parent])(isRight(equalTo(Child1()))) &&
+ assert("""{"child2":{}}""".fromJson[Parent])(isRight(equalTo(Child2()))) &&
+ assert("""{"type":"child1"}""".fromJson[Parent])(isLeft(equalTo("(invalid disambiguator)")))
+ },
  test("sum alternative encoding") {
  import examplealtsum._
 
  assert("""{"hint":"Cain"}""".fromJson[Parent])(isRight(equalTo(Child1()))) &&
  assert("""{"hint":"Abel"}""".fromJson[Parent])(isRight(equalTo(Child2()))) &&
  assert("""{"hint":"Samson"}""".fromJson[Parent])(isLeft(equalTo("(invalid disambiguator)"))) &&
  assert("""{"Cain":{}}""".fromJson[Parent])(isLeft(equalTo("(missing hint 'hint')")))
+ },
+ test("sum alternative encoding with hint names") {
+ import examplealtsumhintnames._
+
+ assert("""{"hint":"child1"}""".fromJson[Parent])(isRight(equalTo(Child1()))) &&
+ assert("""{"hint":"Abel"}""".fromJson[Parent])(isRight(equalTo(Child2()))) &&
+ assert("""{"hint":"Child1"}""".fromJson[Parent])(isLeft(equalTo("(invalid disambiguator)"))) &&
+ assert("""{"child1":{}}""".fromJson[Parent])(isLeft(equalTo("(missing hint 'hint')")))
  }
  )
  )
@@ -59,6 +74,15 @@ object DeriveSpec extends ZIOSpecDefault {
  case class Child2() extends Parent
  }
 
+ object examplesumhintnames {
+ @jsonDerive
+ @jsonHintNames(SnakeCase)
+ sealed abstract class Parent
+
+ case class Child1() extends Parent
+ case class Child2() extends Parent
+ }
+
  object exampleempty {
  @jsonDerive
  case class Empty(a: Option[String])
@@ -78,6 +102,19 @@ object DeriveSpec extends ZIOSpecDefault {
  case class Child2() extends Parent
  }
 
+ object examplealtsumhintnames {
+
+ @jsonDerive
+ @jsonDiscriminator("hint")
+ @jsonHintNames(SnakeCase)
+ sealed abstract class Parent
+
+ case class Child1() extends Parent
+
+ @jsonHint("Abel")
+ case class Child2() extends Parent
+ }
+
  object logEvent {
  @jsonDerive(JsonDeriveConfig.Decoder)
  case class Event(at: Long, message: String, a: Seq[String] = Nil)

zio-json/shared/src/main/scala-2.x/zio/json/macros.scala

@@ -175,6 +175,12 @@ private[json] object jsonMemberNames {
  */
 final case class jsonHint(name: String) extends Annotation
 
+/**
+ * If used on a sealed class will determine the strategy of type hint value transformation for disambiguating
+ * classes during serialization and deserialization. Same strategies are provided as for [[jsonMemberNames]].
+ */
+final case class jsonHintNames(format: JsonMemberFormat) extends Annotation
+
 /**
  * If used on a case class, will exit early if any fields are in the JSON that
  * do not correspond to field names in the case class.
@@ -200,11 +206,13 @@ final class jsonExclude extends Annotation
  * @param sumTypeHandling see [[jsonDiscriminator]]
  * @param fieldNameMapping see [[jsonMemberNames]]
  * @param allowExtraFields see [[jsonNoExtraFields]]
+ * @param sumTypeMapping see [[jsonHintNames]]
  */
 final case class JsonCodecConfiguration(
  sumTypeHandling: SumTypeHandling = WrapperWithClassNameField,
  fieldNameMapping: JsonMemberFormat = IdentityFormat,
- allowExtraFields: Boolean = true
+ allowExtraFields: Boolean = true,
+ sumTypeMapping: JsonMemberFormat = IdentityFormat
 )
 
 object JsonCodecConfiguration {
@@ -416,10 +424,12 @@ object DeriveJsonDecoder {
  }
 
  def split[A](ctx: SealedTrait[JsonDecoder, A])(implicit config: JsonCodecConfiguration): JsonDecoder[A] = {
+ val jsonHintFormat: JsonMemberFormat =
+ ctx.annotations.collectFirst { case jsonHintNames(format) => format }.getOrElse(config.sumTypeMapping)
  val names: Array[String] = ctx.subtypes.map { p =>
  p.annotations.collectFirst { case jsonHint(name) =>
  name
- }.getOrElse(p.typeName.short)
+ }.getOrElse(jsonHintFormat(p.typeName.short))
  }.toArray
  val matrix: StringMatrix = new StringMatrix(names)
  lazy val tcs: Array[JsonDecoder[Any]] =
@@ -594,10 +604,12 @@ object DeriveJsonEncoder {
  }
 
  def split[A](ctx: SealedTrait[JsonEncoder, A])(implicit config: JsonCodecConfiguration): JsonEncoder[A] = {
+ val jsonHintFormat: JsonMemberFormat =
+ ctx.annotations.collectFirst { case jsonHintNames(format) => format }.getOrElse(config.sumTypeMapping)
  val names: Array[String] = ctx.subtypes.map { p =>
  p.annotations.collectFirst { case jsonHint(name) =>
  name
- }.getOrElse(p.typeName.short)
+ }.getOrElse(jsonHintFormat(p.typeName.short))
  }.toArray
  def discrim =
  ctx.annotations.collectFirst { case jsonDiscriminator(n) => n }.orElse(config.sumTypeHandling.discriminatorField)

zio-json/shared/src/main/scala-3/zio/json/macros.scala

@@ -64,6 +64,9 @@ case object PascalCase extends JsonMemberFormat {
 case object KebabCase extends JsonMemberFormat {
  override def apply(memberName: String): String = jsonMemberNames.enforceSnakeOrKebabCase(memberName, '-')
 }
+case object IdentityFormat extends JsonMemberFormat {
+ override def apply(memberName: String): String = memberName
+}
 
 /** zio-json version 0.3.0 formats. abc123Def -> abc_123_def */
 object ziojson_03 {
@@ -175,6 +178,12 @@ private[json] object jsonMemberNames {
  */
 final case class jsonHint(name: String) extends Annotation
 
+/**
+ * If used on a sealed class will determine the strategy of type hint value transformation for disambiguating
+ * classes during serialization and deserialization. Same strategies are provided as for [[jsonMemberNames]].
+ */
+final case class jsonHintNames(format: JsonMemberFormat) extends Annotation
+
 /**
  * If used on a case class, will exit early if any fields are in the JSON that
  * do not correspond to field names in the case class.
@@ -370,10 +379,12 @@ object DeriveJsonDecoder extends Derivation[JsonDecoder] { self =>
  }
 
  def split[A](ctx: SealedTrait[JsonDecoder, A]): JsonDecoder[A] = {
+ val jsonHintFormat: JsonMemberFormat =
+ ctx.annotations.collectFirst { case jsonHintNames(format) => format }.getOrElse(IdentityFormat)
  val names: Array[String] = IArray.genericWrapArray(ctx.subtypes.map { p =>
  p.annotations.collectFirst { case jsonHint(name) =>
  name
- }.getOrElse(p.typeInfo.short)
+ }.getOrElse(jsonHintFormat(p.typeInfo.short))
  }).toArray
 
  val matrix: StringMatrix = new StringMatrix(names)
@@ -594,6 +605,8 @@ object DeriveJsonEncoder extends Derivation[JsonEncoder] { self =>
  }
 
  def split[A](ctx: SealedTrait[JsonEncoder, A]): JsonEncoder[A] = {
+ val jsonHintFormat: JsonMemberFormat =
+ ctx.annotations.collectFirst { case jsonHintNames(format) => format }.getOrElse(IdentityFormat)
  val discrim = ctx
  .annotations
  .collectFirst {
@@ -608,7 +621,7 @@ object DeriveJsonEncoder extends Derivation[JsonEncoder] { self =>
  .annotations
  .collectFirst {
  case jsonHint(name) => name
- }.getOrElse(sub.typeInfo.short)
+ }.getOrElse(jsonHintFormat(sub.typeInfo.short))
 
  out.write("{")
  val indent_ = JsonEncoder.bump(indent)
@@ -635,7 +648,7 @@ object DeriveJsonEncoder extends Derivation[JsonEncoder] { self =>
  .annotations
  .collectFirst {
  case jsonHint(name) => name
- }.getOrElse(sub.typeInfo.short)
+ }.getOrElse(jsonHintFormat(sub.typeInfo.short))
 
  Json.Obj(
  Chunk(
@@ -652,7 +665,7 @@ object DeriveJsonEncoder extends Derivation[JsonEncoder] { self =>
  def getName(annotations: Iterable[_], default: => String): String =
  annotations
  .collectFirst { case jsonHint(name) => name }
- .getOrElse(default)
+ .getOrElse(jsonHintFormat(default))
 
  new JsonEncoder[A] {
  def unsafeEncode(a: A, indent: Option[Int], out: Write): Unit = {

zio-json/shared/src/test/scala-2.x/zio/json/ConfigurableDeriveCodecSpec.scala

@@ -113,6 +113,19 @@ object ConfigurableDeriveCodecSpec extends ZIOSpecDefault {
  expectedObj.toJson == expectedStr
  )
  },
+ test("should override sum type mapping") {
+ val expectedStr = """{"$type":"case_class","i":1}"""
+ val expectedObj: ST = ST.CaseClass(i = 1)
+
+ implicit val config: JsonCodecConfiguration =
+ JsonCodecConfiguration(sumTypeHandling = DiscriminatorField("$type"), sumTypeMapping = SnakeCase)
+ implicit val codec: JsonCodec[ST] = DeriveJsonCodec.gen
+
+ assertTrue(
+ expectedStr.fromJson[ST].toOption.get == expectedObj,
+ expectedObj.toJson == expectedStr
+ )
+ },
  test("should prevent extra fields") {
  val jsonStr = """{"someField":1,"someOtherField":"a","extra":123}"""
 

zio-json/shared/src/test/scala/zio/json/CodecSpec.scala

@@ -78,6 +78,13 @@ object CodecSpec extends ZIOSpecDefault {
  assert("""{"Child2":{}}""".fromJson[Parent])(isRight(equalTo(Child2()))) &&
  assert("""{"type":"Child1"}""".fromJson[Parent])(isLeft(equalTo("(invalid disambiguator)")))
  },
+ test("sum encoding with hint names") {
+ import examplesumhintnames._
+
+ assert("""{"child1":{}}""".fromJson[Parent])(isRight(equalTo(Child1()))) &&
+ assert("""{"child2":{}}""".fromJson[Parent])(isRight(equalTo(Child2()))) &&
+ assert("""{"type":"child1"}""".fromJson[Parent])(isLeft(equalTo("(invalid disambiguator)")))
+ },
  test("sum alternative encoding") {
  import examplealtsum._
 
@@ -86,6 +93,14 @@ object CodecSpec extends ZIOSpecDefault {
  assert("""{"hint":"Samson"}""".fromJson[Parent])(isLeft(equalTo("(invalid disambiguator)"))) &&
  assert("""{"Cain":{}}""".fromJson[Parent])(isLeft(equalTo("(missing hint 'hint')")))
  },
+ test("sum alternative encoding with hint names") {
+ import examplealtsumhintnames._
+
+ assert("""{"hint":"child1"}""".fromJson[Parent])(isRight(equalTo(Child1()))) &&
+ assert("""{"hint":"Abel"}""".fromJson[Parent])(isRight(equalTo(Child2()))) &&
+ assert("""{"hint":"Child1"}""".fromJson[Parent])(isLeft(equalTo("(invalid disambiguator)"))) &&
+ assert("""{"child1":{}}""".fromJson[Parent])(isLeft(equalTo("(missing hint 'hint')")))
+ },
  test("key transformation") {
  import exampletransformkeys._
  val kebabed = """{"shish123-kebab":""}"""
@@ -231,6 +246,17 @@ object CodecSpec extends ZIOSpecDefault {
  case class Child2() extends Parent
  }
 
+ object examplesumhintnames {
+ @jsonHintNames(SnakeCase)
+ sealed abstract class Parent
+
+ object Parent {
+ implicit val codec: JsonCodec[Parent] = DeriveJsonCodec.gen[Parent]
+ }
+ case class Child1() extends Parent
+ case class Child2() extends Parent
+ }
+
  object exampleempty {
  case class Empty(a: Option[String])
 
@@ -242,6 +268,7 @@ object CodecSpec extends ZIOSpecDefault {
  object examplealtsum {
 
  @jsonDiscriminator("hint")
+ @jsonHintNames(SnakeCase)
  sealed abstract class Parent
 
  object Parent {
@@ -255,6 +282,22 @@ object CodecSpec extends ZIOSpecDefault {
  case class Child2() extends Parent
  }
 
+ object examplealtsumhintnames {
+
+ @jsonDiscriminator("hint")
+ @jsonHintNames(SnakeCase)
+ sealed abstract class Parent
+
+ object Parent {
+ implicit val codec: JsonCodec[Parent] = DeriveJsonCodec.gen[Parent]
+ }
+
+ case class Child1() extends Parent
+
+ @jsonHint("Abel")
+ case class Child2() extends Parent
+ }
+
  object exampletransformkeys {
  @jsonMemberNames(KebabCase)
  case class Kebabed(shish123Kebab: String)