Since mapstruct 1.3.0.Beta2 it's possible to use builders for immutable classes. According to the documentation you can implement your custom builder provider logic. This project take advantage of this and provide a custom BuilderProvider for kotlin data classes.

So instead of this (source)

data class PersonDto(var firstName: String?, var lastName: String?, var phone: String?, var birthdate: LocalDate?) {
    // Necessary for MapStruct
    constructor() : this(null, null, null, null)
} 

We can do this

@KotlinBuilder
data class PersonDto(val firstName: String, val lastName: String, val phone: String, val birthdate: LocalDate)

With a mapper

@Mapper
interface PersonMapper {
    fun map(person: Person): PersonDto
}

Please keep in your mind that this repository still a proof of concept, and absolutely not ready for production. A contribution, idea, discussion is always welcomed

A version which is using the mapstruct 1.3.0.Beta2 is available on jitpack.io.

First of all add maven { url 'https://jitpack.io' } to your repositories, and then add these to your dependencies

api("com.github.pozo.mapstruct-kotlin:mapstruct-kotlin:1.3.0.Beta2")

kapt("com.github.pozo.mapstruct-kotlin:mapstruct-kotlin-processor:1.3.0.Beta2")

• annotation contains only the KotlinBuilder annotation
• builder-processor responsible for generating the builders for the kotlin data classes
• processor responsible for extending the DefaultBuilderProvider functionality according to the documentation
• test responsible for demonstrating this library usage

The building order is important since the processor project depends on builder-processor and mapstruct.

./gradlew clean build publishToMavenLocal

./gradlew -p example clean build

• Map with custom types are not working
• Look over kotlin-builder-annotation project and replace with class generating module (builder-processor)
• Writing tests
• Versioning and release process

Please see LICENSE file

Zoltan Polgar - [email protected]

Please do not hesitate to contact me if you have any further questions.