Can I control mapping order with MapStruct?

Question

I have a use case where I want to map objects to a ByteBuffer for transmission....

    @Mapper
    public static interface ByteBufferMapper {
        public static ByteBufferMapper INSTANCE = Mappers.getMapper(ByteBufferMapper.class);

        default byte toByte(ByteBuffer buffer) {
            byte b = buffer.get();
            return b;
        }
    }

    public static class Dto {
        public byte b;
        public byte bb;
        ...
    }

    @Mapper(uses = ByteBufferMapper.class)
    public static interface DtoMapper {
        public static DtoMapper INSTANCE = Mappers.getMapper(DtoMapper.class);

        @Mapping(source = "buffer", target = "bb")
        @Mapping(source = "buffer", target = "b")
        Dto byteBufferToDto(ByteBuffer buffer);
    }

    public static void main( String[] args ) {
        ByteBuffer buffer = ByteBuffer.allocate(2).put((byte) 0xFF).put((byte) 0x00).flip();
        System.out.println(DtoMapper.INSTANCE.byteBufferToDto(buffer));
    }

Is there a way I can control MapStructs mapping order so the b variable gets populated with the 0xFF and bb gets populated with the 0x00 value?

Answer 1

Yes you can by means of @Mapping.dependsOn.

Like this:

    @Mappings({
        @Mapping(target = "surName", source = "lastName", dependsOn = "middleName"),
        @Mapping(target = "middleName", dependsOn = "givenName"),
        @Mapping(target = "givenName", source = "firstName")
    })
    AddressDto addressToDto(Address address);