Mastering Object Mapping in Spring Boot with @Mapper and @Mapping

In Spring Boot, if you’re working with data transfer objects (DTOs) or entity mapping between layers (e.g., between service and persistence layers), using a mapping framework like MapStruct can be helpful. The @Mapper and @Mapping annotations are part of MapStruct, a code generator that simplifies the process of mapping between Java objects.

Key Concepts of MapStruct:

1. @Mapper:

This annotation is applied to an interface or abstract class. It indicates that this interface is a Mapper, and the MapStruct processor will automatically generate an implementation for it.

@Mapper
public interface UserMapper {
    UserDTO toDto(User entity);
    User toEntity(UserDTO dto);
}

In this example, UserMapper is a mapper interface that will map a User entity to UserDTO and vice versa.

@Mapping:

This annotation is used inside a Mapper interface when you want to explicitly define how fields in one object map to fields in another. It is used when the fields don’t have a direct match or if additional logic is required.

@Mapper
public interface UserMapper {

    @Mapping(source = "name", target = "fullName")
    @Mapping(source = "address.street", target = "streetName")
    UserDTO toDto(User entity);

    @Mapping(source = "fullName", target = "name")
    @Mapping(source = "streetName", target = "address.street")
    User…