Spring Boot / MapStruct: Parameter 1 of constructor required a bean... Consider defining a bean of type - spring

Question

I don't know so much about Java, but I thought it should be enough to manage this little task...
I'm building a microservice, which provides Songs and list of songs via several Rest-Endpoints. But it doesn't just return a song when called, it also has to contact another service and enhance the song object with additional information. For this I implemented a Dto-Class and I use mapstruct to handle logic behind. I also did this in other projects with no problems. But now I'm struggling, because of this error, which I don't know how to solve - it says:
Parameter 1 of constructor in
mk.microservices.songsservice.services.SongServiceImpl required a bean
of type 'mk.microservices.songsservice.web.mapper.SongMapper' that
could not be found.
Action:
Consider defining a bean of type
'mk.microservices.songsservice.web.mapper.SongMapper' in your
configuration.
Here are excerpts from my code:
SongServiceImpl
import lombok.RequiredArgsConstructor;
import mk.microservices.songsservice.domain.Song;
import mk.microservices.songsservice.repositories.SongRepository;
import mk.microservices.songsservice.web.mapper.SongMapper;
import mk.microservices.songsservice.web.model.SongDto;
import org.springframework.stereotype.Service;
import java.util.List;
import java.util.Optional;
#RequiredArgsConstructor
#Service
public class SongServiceImpl implements SongService {
private final SongRepository songRepository;
private final SongMapper songMapper;
#Override
public SongDto getSongById(Integer id) {
return songMapper.songToSongDto(songRepository.findById(id));
}
#Override
public List<Song> getAllSongs() {
return songRepository.findAll();
}
....
}
SongMapper
import org.mapstruct.DecoratedWith;
import java.util.Optional;
#MapStruct
#DecoratedWith(SongMapperDecorator.class)
public interface SongMapper {
SongDto songToSongDto(Optional<Song> song);
SongDto songToSongDtoWithSongInfo(Song song);
Song songDtoToSong(SongDto songDto);
}
SongMapperDecorator
import org.springframework.beans.factory.annotation.Autowired;
import java.util.Optional;
public class SongMapperDecorator implements SongMapper {
private SongInfoService songInfoService;
private SongMapper mapper;
#Autowired
public void setMapper(SongMapper songMapper) { this.mapper = songMapper; }
#Override
public SongDto songToSongDto(Optional<Song> song) {
return mapper.songToSongDto(song);
}
#Override
public SongDto songToSongDtoWithSongInfo(Song song) {
SongDto songDto = mapper.songToSongDto(Optional.ofNullable(song));
SongInfo songInfo = songInfoService.getSongInfoBySongId(song.getId());
songDto.setDescription(songInfo.getDescription());
return songDto;
}
#Override
public Song songDtoToSong(SongDto songDto) {
return mapper.songDtoToSong(songDto);
}
}
Also did a clean, validate and compile without any errors. But when I did the verify, I got this:
[ERROR] Failed to execute goal
org.apache.maven.plugins:maven-compiler-plugin:3.8.0:compile
(default-compile) on project songs-service: Resolution of
annotationProcessorPath dependencies failed: Missing: [ERROR]
---------- [ERROR] 1) org.mapstruct:mapstruct-processor:jar:1.4.2
My POM looks like this:
The dependency for mapstruct:
<dependency>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct</artifactId>
<version>1.4.2.Final</version>
</dependency>
And the plugin for enabling mapstruct and lombok working together:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
<configuration>
<annotationProcessorPaths>
<path>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct-processor</artifactId>
<version>${mapstruct.version}</version>
</path>
<path>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
</path>
</annotationProcessorPaths>
<compilerArgs>
<compilerArg>
-Amapstruct.defaultComponentModel=spring
</compilerArg>
</compilerArgs>
</configuration>
</plugin>
Would be very glad, if someone could help me solving this. Already googled a lot and didn't find anything useful yet.
Br,
Mic

Answer 1

As it is clear from the error the SongServiceImpl requires a bean SongMapper but Mapstruct do not generate a spring bean by default. i,e it will not add #Component annotation in the generated class, so we need to explicitly mention to generate a class that can be used to create spring bean.
so instead of #MapStruct use #Mapper(componentModel = "spring") in the mapper interface.

Answer 2

Solved it finally, changed the mapstruct version in my POM to 1.4.2.Final (instead of just 1.4.2). Now it works...
Got the hint frome Mapstruct-Documentation here...

Answer 3

Solved this finally. I used this configuration (mapstruct + lombok)
Also installed m2e-apt plugin in eclipse.
pom.xml
<dependency>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct</artifactId>
<version>1.4.2.Final</version>
</dependency>
<dependency>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct-processor</artifactId>
<version>1.4.2.Final</version>
</dependency>
------------------------------------------------------------
<configuration>
<source>1.8</source> <!-- depending on your project -->
<target>1.8</target> <!-- depending on your project -->
<annotationProcessorPaths>
<path>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
</path>
<!-- other annotation processors -->
</annotationProcessorPaths>
<compilerArgs>
<compilerArg>
-Amapstruct.defaultComponentModel=spring
</compilerArg>
</compilerArgs>
</configuration>