MapStruct

Imagine a big project with a few dozen APIs, and hundreds of Model → DTO conversions... Doing this manually can quickly create much boilerplate code, be prone to error, and consume a lot of time. Luckily for us, there are multiple object mapping frameworks for Java.

Mappers are a “choose your own adventure” situation. The one I recommend is MapStruct. Let's add it to the project

1. We need MapStruct Core, MapStruct Processor, and Lombok Mapstruct Binding dependencies. Add them in the build.gradle dependencies section:

   build.gradle

   implementation 'org.mapstruct:mapstruct:1.6.3'
   annotationProcessor 'org.mapstruct:mapstruct-processor:1.6.3'
   annotationProcessor 'org.projectlombok:lombok-mapstruct-binding:0.2.0'

2. Rewrite UserMapper so it becomes an interface annotated by MapStruct.

   src/main/java/dev/pollito/users_manager/adapter/in/rest/mapper/UserMapper.java

   package dev.pollito.users_manager.adapter.in.rest.mapper;
   
   import static org.mapstruct.MappingConstants.ComponentModel.SPRING;
   
   import dev.pollito.users_manager.adapter.in.rest.dto.UserResponseDTO;
   import dev.pollito.users_manager.domain.model.User;
   import org.mapstruct.Mapper;
   
   @Mapper(componentModel = SPRING)
   public interface UserMapper {
     UserResponseDTO map(User u);
   }

Right-click the main class → Run. Then go to http://localhost:8080/users. Everything should be working as usual.

Remember to commit the progress so far.

git add .
git commit -m "mapstruct"