@AfterMapping and @Mapper(unmappedTargetPolicy = ReportingPolicy.ERROR) reports an error at compile time

[stessy]

Hi,

I'm currently experimenting mapstruct and I don't understand a reported error at compile time.

I have an interface GrantingResponseMapper annotated with @Mapper(unmappedTargetPolicy = ReportingPolicy.ERROR)

Here is the class:

@Mapper(unmappedTargetPolicy = ReportingPolicy.ERROR)
public interface GrantingResponseMapper {

    GrantingResponseMapper INSTANCE = Mappers.getMapper(GrantingResponseMapper.class);

    @Mapping(target = "decisionId", ignore = true)
    GrantingResponseVo mapFrom(GrantingDecisionResponse response);

    @AfterMapping
    default void mapSecondaryTelemDecisions(GrantingDecisionResponse source, @MappingTarget GrantingResponseVo.GrantingResponseVoBuilder target) {
        List<TelemDecision> telemDecisionsSecondaryList = source.getTelemDecisionsSecondaryList();
        if (CollectionUtils.isNotEmpty(telemDecisionsSecondaryList)) {
            if (!telemDecisionsSecondaryList.isEmpty()) {
                target.secondaryTelemDecision1(telemDecisionsSecondaryList.get(0));
            }
            if (telemDecisionsSecondaryList.size() > 1) {
                target.secondaryTelemDecision2(telemDecisionsSecondaryList.get(1));
            }
            if (telemDecisionsSecondaryList.size() > 2) {
                target.secondaryTelemDecision3(telemDecisionsSecondaryList.get(2));
            }
            if (telemDecisionsSecondaryList.size() > 3) {
                target.secondaryTelemDecision4(telemDecisionsSecondaryList.get(3));
            }
        }
    }
}

If I compile the class an error is reported that fields secondaryTelemDecision1, secondaryTelemDecision2, secondaryTelemDecision3, and secondaryTelemDecision4 are not mapped.

If I remove the unmappedTargetPolicy the code compiles correctly, and I can see that AfterMapping method is called:

mapSecondaryTelemDecisions( response, grantingResponseVo );

Maybe the mapping is not correctly done on my side. If this is the case, what would be the correct mapping to implement to prevent from having a compilation error?

Thanks for your help.
Kind Regards,
Stessy

[filiphr]

The reason why you are getting the error is due to the fact that MapStruct is not able to map those 4 fields. MapStruct has no way of knowing what is being done in the @AfterMapping.

If you want to use ReportingPolicy.ERROR as the unmapped target policy then you should ignore explicitly those 4 methods via @Maping(target = "secondaryTelemDecision1", ignore = true)

I don't know how your objects are created, but in your case I would not expose setters for the secondaryTelemDecision1 and the rest. I would instead do

public class GrantingResponseVo {


    public TelemDecision getSecondaryTelemDecision1() {
        return telemDecisionsSecondaryList != null && !telemDecisionsSecondaryList.isEmpty() ? telemDecisionsSecondaryList.get(0) : null;
    }

}

[stessy]

Thanks for your quick reply.

In fact they are created with Lombok and the builder pattern.

I'm going to use the @mapping annotation to ignore those 4 fields and leave the ReportingPolicy.ERROR in case someone else adds some fields and do not adapt the mapper. The unit tests already check all the fields are correctly mapped.