将对象转换为Long时使用mapstruct的未映射目标属性

Question

在将对象转换为Long时，我在mapstruct上遇到问题，出现以下警告：

warning: Unmapped target property

这里是实体（使用龙目岛的人）：

    @Getter
    @Setter
    @NoArgsConstructor
    @Entity
    public class User {
        ...
        private Set<Address> addresses= new HashSet<>();
        ...
    }

    @Getter
    @Setter
    @NoArgsConstructor
    @Entity
    public class Address {
        ...
        private Town town;
        ...
    }

    @Getter
    @Setter
    @NoArgsConstructor
    @Entity
    public class Town {
        ...
        private Long id;
        ...
    }

和DTO：

    @Getter
    @Setter
    @NoArgsConstructor
    public class UserDTO {
        ...
        private Set<AddressDTO> addresses= new HashSet<>();
        ...
    }

    @Getter
    @Setter
    @NoArgsConstructor
    public class AddressDTO {
        ...
        private Long townId;
        ...
    }

在addressDTO中，我需要townId而不是town对象。这是映射器：

@Mapper
public interface UserMapper {

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

    UserDTO userToUserDTO(User user);

}

@Mapper
public interface AddressMapper {

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

    @Mapping(target = "townId", source = "town")
    AddressDTO addressToAddressDTO(Address address);

    default Long getTownId(Town town) {
        return town.getId();
    }
}

我为AddressMapper编写了一个有效的单元测试：

AddressDTO addressDTO = AddressMapper.INSTANCE.addressToAddresslDTO( address);

但不适用于UserMapper：

UserDTO userDTO = userMapper.INSTANCE.userToUserDTO( user);

我有以下警告：

warning: Unmapped target property: "townId". Mapping from Collection element "fr.example.myproj.entity.Adress adresses" to "fr.example.myproj.service.dto.AdressDTO adresses".
    UserDTO userToUserDTO(User user);

Answer 1

@Mapper
public interface UserMapper {

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

    UserDTO userToUserDTO(User user);

    default AddressDTO addressToAddressDTO(Address address) {
        return AddressMapper.INSTANCE.addressToAdressDTO( address );
    }

}