Map abstract class to DTO with MapStruct

Question

I found a lot of topics to this but all solutions went into a wrong direction in my eyes.

So... How do i use MapStruct mapping for this case?

abstract class Person:

public abstract class Person implements Serializable{

     private String name;
     private String somethingToIgnore

     //Getter and Setter

}

The normal Mapper doesn´t work:

@Mapper(componentModel = 'cdi')
public interface PersonMapper{

    @Mapping(target = 'somethingToIgnore', ignore = 'true')
    Person toPerson(PersonDTO source);

    @InheritInverseConfiguration
    PersonDTO toPersonDtO(Person source);

}

I am not allowed to map an abstract class. I should use the a factory method. I tried but i simply have no clue how this factoy method should look like...

My attempt:

@Mapper
public interface PersonMapper {

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

    Person toPerson(PersonDTO source);

    PersonDTO toPersonDtO(Person source);
}

@Mapper
public abstract class PersonMapper {

    public static final PersonMapper INSTANCE = Mappers.getMapper( PersonMapper.class );

    Person toPerson(PersonDTO source);

    PersonDTO toPersonDtO(Person source);
}

What am i missing and doing wrong ? Thanks in advance.

Answer 1

MapStruct doesn't know how to map to abstract class, because it cannot instantiate it. I expect that you have some implementation of Person. You need to provide method which will create object of a Person like this:

@Mapper
public interface PersonMapper {

    Person toPerson(PersonDTO source);

    PersonDTO toPersonDtO(Person source);

    default Person createPerson() {
        return new PersonImpl();
    }
}

This way MapStruct will use this method to create Person instance and than map the properties like usual. You can find more about object factories in the documentation.