DeepClone mapping control not generating second tier functions to clone for objects stored in collection-type content

[ludgerb]

Expected behavior

In 1.5.3.Final DeepClone is not working if second thier objects are stored in collection type content.

Let's say, we have nested objects as follows:

Person -> List

@Data
@NoArgsConstructor
public class Lead {
    private List<Address> addresses;
}

@Data
@NoArgsConstructor
public class Address {
    private String formattedAddress;
}

Expectation is, when calling clonePerson on person, since it's a deepCopy, the addresses will also be cloned.
i.e. the following test should hold:

@Test
void testAddressClone() {
    var address = new Address();
    address.setFormattedAddress("original address");
    var person = new Person();
    person.setAddresses(List.of(address));

    // perform deep clone
    var clonedPerson = mapper.clonePerson(person);
    
    // modify original => should not reflect on the copy
    address.setFormattedAddress("new address");
    
   assertNotEquals(address.getFormattedAddress(), clonedPerson.getAddresses().get(0).getFormattedAddress());
}

Please compare this to the behavior in #3135

Actual behavior

Generated code is:

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2024-01-29T12:25:17+0100",
    comments = "version: 1.5.5.Final, compiler: javac, environment: Java 17.0.9"
)
@Component
public class LeadMapperImpl extends PersonMapper {
    @Override
    public Lead copyLead(Lead person) {
        if ( person == null ) {
            return null;
        }
        Person person1 = new Person();

        lead1.setAddresses( addressListToAddressList( lead.getAddresses() ) );
    }

    protected List<Address> addressListToAddressList(List<Address> list) {
        if ( list == null ) {
            return null;
        }

        List<Address> list1 = new ArrayList<Address>( list.size() );
        for ( Address address : list ) {
            list1.add( address );
        }

        return list1;
    }
}

I.e. an addressToAddress method is missing and not called in the for loop copying the list.

In contrast, when replacing the original Person by this definition, an addressToAddress method is generated (so here we have expected behavior):

@Data
@NoArgsConstructor
public class Lead {
    private Address address;
}

@Data
@NoArgsConstructor
public class Address {
    private String formattedAddress;
}

Steps to reproduce the problem

@Mapper(componentModel = "spring")
public abstract class PersonMapper {
  @BeanMapping(
      mappingControl = DeepClone.class,
      nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS)
    public abstract Person clonePerson(Person person);
}

MapStruct Version

1.5.5-Final

[filiphr]

Thanks for the detailed example @ludgerb this does looks similar to #3135. We'll look into it and fix it.

[Zegveld]

Looked into it a bit, but not sure how to fix this.

Here is a work-around:

@Mapper( componentModel = "spring", mappingControl = DeepClone.class )
public abstract class PersonMapper {
  @BeanMapping( nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS )
    public abstract Person clonePerson(Person person);
}

The problem is that the IterableMappingOptions do not fall-back to the configuration for mappingControl in the BeanMappingOptions.
I am not certain if we want this even, and what the impact would be for other behavior.

If the mappingControl is defined on the @Mapper itself however it is inherited by both BeanMappingOptions and IterableMappingOptions.

[filiphr]

Thanks for looking into this @Zegveld. I also think that it would be a bit tricky to solve this. I'll move it to 1.7 to see if we can do something there.

In any case, the approach by using the mapping control in @Mapping is a good workaround for now.