MapStruct: How can I do filter to fields which I want and don't want to mapping?

Question

I have a DTO. I want to map not all field in MapStruct.

For example, User and UserDTO

public class UserDTO {

    private Long id;
    private String username;
    private String password;
    private String email;
    private boolean active;
    private String activationCode;
    private Set<Role> roles;

}

I have next mapper:

User fromUserDTO(UserDTO userDTO);

I don't want to map id, username, password, email. How can I point out that these fields don't get stuck?

User user = fromUserDTO(userDTO);

Answer 1

I've found the answer.

1. I can ignore a field:

@Mapping(target = "id", ignore = true)
User fromUserDTO(UserDTO userDTO);

2. Or I can ignore a field which equals null:

@Mapping(target="id", nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.IGNORE)
User fromUserDTO(UserDTO userDTO);