Reflective and code gen implementations for serializing Kotlin sealed classes via Moshi polymorphic adapters.
Simple annotated a sealed class with @JsonClass
with a generator
value of sealed:{typeLabel}
.
{typeLabel}
is the value of the type label that should be used for a Moshi
PolymorphicJsonAdapterFactory
. Annotate subtypes with @TypeLabel
to indicate their type label
value. One object
can be used as an unknown default value via @DefaultObject
, or the sealed
type can be annotated with @DefaultNull
to indicate that null
should be the default.
@JsonClass(generateAdapter = true, generator = "sealed:type")
sealed class Message {
@TypeLabel("success")
@JsonClass(generateAdapter = true)
data class Success(val value: String) : Message()
@TypeLabel("error")
@JsonClass(generateAdapter = true)
data class Error(val error_logs: Map<String, Any>) : Message()
@DefaultObject
object Unknown : Message()
}
Moshi-sealed can be used via reflection or code generation. Note that you must include the
moshi-adapters
artifact as a dependency, as that's where the PolymorphicJsonAdapter
implementation
lives.
@TypeLabel
and default indicator annotations are available in the moshi-sealed-annotations
artifact.
kapt "dev.zacsweers.moshisealed:moshi-sealed-annotations:{version}"
Code gen works via annotation processor, and only requires adding the kapt dependency:
kapt "dev.zacsweers.moshisealed:moshi-sealed-codegen:{version}"
No runtime Moshi instance configuration is needed, code gen will generate JsonAdapter
s in a way that Moshi understands
natively.
Reflection works via MoshiSealedJsonAdapterFactory
. Just add this in moshi before
KotlinJsonAdapterFactory
in your Moshi instance construction.
val moshi = Moshi.Builder()
.add(MoshiSealedJsonAdapterFactory())
.add(KotlinJsonAdapterFactory())
.build()
Gradle dependency:
implementation "dev.zacsweers.moshisealed:moshi-sealed-reflect:{version}"
Snapshots of the development version are available in Sonatype's snapshots repository.
Copyright (C) 2019 Zac Sweers
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.