To be used in conjunction with flatten.
It can be applied on one or more of case class fields in a sealed hierarchy to instruct the
auto-materialized GenCodec that this particular field may appear before _case field in the serialized format
during reading.
@flatten sealedtrait Base
caseclass FirstCase(@outOfOrder tag: String, int: Int) extends Base
caseclass SecondCase(dbl: Double) extends Base
object Base {
implicitval codec: GenCodec[Base] = GenCodec.materialize[Base]
}
The following JSON (assuming this is the representation used) would correctly deserialize as
FirstCase("someTag", 42):
Field annotated with @outOfOrder annotation doesn't have to be present in every case class, but if it is present,
all case classes must annotate it and give it exactly the same type. The annotation may also be inherited, e.g.
@flatten sealedtrait Base {
@outOfOrder def tag: String
}
caseclass FirstCase(tag: String, int: Int) extends Base
caseclass SecondCase(tag: String, dbl: Double) extends Base
The direct motivation for this annotation was the ability to use flatten on MongoDB entities with an _id field.
When reading entities from MongoDB, the _id field is always at the beginning of a BSON document and therefore
GenCodec must be able to read it before it knows which case class of sealed hierarchy is being deserialized.
To be used in conjunction with flatten. It can be applied on one or more of case class fields in a sealed hierarchy to instruct the auto-materialized
GenCodecthat this particular field may appear before_casefield in the serialized format during reading.The following JSON (assuming this is the representation used) would correctly deserialize as
FirstCase("someTag", 42):{"tag": "someTag", "_case": "FirstCase", "int": 42}Field annotated with
@outOfOrderannotation doesn't have to be present in every case class, but if it is present, all case classes must annotate it and give it exactly the same type. The annotation may also be inherited, e.g.The direct motivation for this annotation was the ability to use flatten on MongoDB entities with an
_idfield. When reading entities from MongoDB, the_idfield is always at the beginning of a BSON document and thereforeGenCodecmust be able to read it before it knows which case class of sealed hierarchy is being deserialized.