@Service Class Not Autowired in org.mapstruct.@Mapper Class

Question

I am trying to add json serialization to my SpringBoot app using MapStruct. @Mapper class uses @Service to add some "aftermapping" logic. The problem is, that this @Service class is not autowired.

This is my Mapper class:

@Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE, componentModel = "spring")
public abstract class InstrumentMapper {

    protected MarketDataService marketDataService; // is @Service

    @Mapping(target = "marketCode",
            expression = "java(instrument.getMarket().getCode())")
    public abstract InstrumentDto fromInstrument(Instrument instrument);

    public abstract List<InstrumentDto> fromInstruments(List<Instrument> instruments);

    @Mapping(target = "market",
            expression = "java(marketDataService.findMarketByCode(instrumentDto.getMarketCode()))")
    public abstract Instrument toInstrument(InstrumentDto instrumentDto);

    public abstract List<Instrument> toInstruments(List<InstrumentDto> instrumentDtos);

    @Autowired
    public void setMarketDataService(MarketDataService marketDataService) {
        this.marketDataService = marketDataService;
    }
}

When toInstrument method is called, application fails with NPE, trying to marketDataService.findMarketByCode(instrumentDto.getMarketCode()).

Hopefully, this information will be enough. Let me know if anything else is needed.

Thanks in advance!

Update:

MarketDataService class. It is added to the context through @Service annotation.

@Service
public class MarketDataService {

    @Autowired
    private InstrumentRepository instrumentRepository;

    public Instrument findInstrumentByCode(String code) {
        return instrumentRepository.findFirstByCode(code);
    }

    public List<InstrumentDto> getAllInstrumentDtos() {
        List<Instrument> instruments = getAllInstruments();
        List<InstrumentDto> dtos = Mappers.getMapper(InstrumentMapper.class).fromInstruments(instruments);
        return dtos;
    }

    public void updateInstrument(InstrumentDto instrumentDto) {
        Instrument instrument = findInstrumentByCode(instrumentDto.getCode());
        if (instrument == null) {
            throw new IllegalArgumentException("Market with given code not found!");
        }
        instrumentRepository.delete(instrument);
        instrument = Mappers.getMapper(InstrumentMapper.class).toInstrument(instrumentDto);
        instrumentRepository.save(instrument);
    }
}

The algorithm is the following: @Controller class gets PUT request and calls MarketDataService.updateInstrument method with the body of the request (instrumentDto parameter). The latter one calls toInstrument method with the same parameter.

please add also the class and the code that calls toInstrument method — Panagiotis Bougioukos, Jul 20 '21 at 15:36
Edit your question with code that shows us how you added MarketDataService to the application context. Through Component annotation or Bean annotation ? — Spasoje Petronijević, Jul 20 '21 at 15:38
What is your reason for using a setter instead of the constructor? — chrylis -cautiouslyoptimistic-, Jul 20 '21 at 15:43
@chrylis-cautiouslyoptimistic- tried both. This is just the latest version :) — abubakirov, Jul 20 '21 at 16:05
If you have a constructor argument, it _should not be possible_ for it to be uninitialized. Note that using field injection is fragile and generally discouraged. — chrylis -cautiouslyoptimistic-, Jul 20 '21 at 16:06
@chrylis-cautiouslyoptimistic- but this is an abstract class. can i create a custom constructor? — abubakirov, Jul 20 '21 at 16:09
Sure you can. (The one question is whether MapStruct knows how to make a `super` call from its generated concrete class, and I'm not certain about that.) — chrylis -cautiouslyoptimistic-, Jul 20 '21 at 16:19
Your mapper instance you are using isn't managed by Spring. You are doing `Mappers.getMapper(InstrumentMapper.class)` which creates one outside the scope of spring. YOu need to inject the mapper into the service (which will lead to another issue of a circular dependency). — M. Deinum, Jul 20 '21 at 17:56

score 1 · Accepted Answer · answered Jul 20 '21 at 19:16

The reason why you have an NPE is because you are using the MapStruct Mappers factory for a non default component model.

The Mappers factory does not perform any dependency injections.

You have to inject your mapper in your MarketDataService. Be careful when doing that because you have a cyclic dependency.

In addition to that the patterns you are using in your Mapper are not really the right ones. You are using an expression when a simple source will do.

e.g.

@Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE, componentModel = "spring")
public abstract class InstrumentMapper {

    protected InstrumentRepository instrumentRepository;

    @Mapping(target = "marketCode", source = "market.code")
    public abstract InstrumentDto fromInstrument(Instrument instrument);

    public abstract List<InstrumentDto> fromInstruments(List<Instrument> instruments);

    @Mapping(target = "market", source = "marketCode")
    public abstract Instrument toInstrument(InstrumentDto instrumentDto);

    public abstract List<Instrument> toInstruments(List<InstrumentDto> instrumentDtos);

    protected Instrument findInstrumentByCode(String code) {
        return instrumentRepository.findFirstByCode(code);
    }

    @Autowired
    public void setMarketDataService(MarketDataService marketDataService) {
        this.marketDataService = marketDataService;
    }
}

@Service Class Not Autowired in org.mapstruct.@Mapper Class

1 Answers1

Linked