How to Implement Business Logic in a Spring Data REST Application?

What are the best practices for adding business logic to a Spring Data REST application?

@RestController
public class CustomController {
    @Autowired
    private MyService myService;

    @PostMapping("/my-endpoint")
    public ResponseEntity<MyResponse> createEntity(@RequestBody MyRequest request) {
        MyEntity entity = myService.processRequest(request);
        return new ResponseEntity<>(entity, HttpStatus.CREATED);
    }
}

Adding business logic to a Spring Data REST application can enhance the app’s capability to handle complex requests, validations, and transformations before persisting data to the database. This guide explores several strategies to incorporate business logic efficiently.

@Entity
public class MyEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String status;

    // Getters and Setters
}

@Service
public class MyService {
    public MyEntity processRequest(MyRequest request) {
        // Custom business logic
        MyEntity entity = new MyEntity();
        entity.setName(request.getName());
        entity.setStatus("NEW");
        return entity;
    }
}

Causes

• Need for data validation before persistence
• Custom response formations or data transformations
• Complex business rules that dictate data handling

Solutions

• Utilizing Service classes to encapsulate business logic
• Extending Spring Data REST repositories with custom implementations
• Creating REST controllers for additional endpoints

Mistake: Directly implementing business logic in controllers.

Solution: Always use service classes to manage business logic for better organization and reusability.

Mistake: Ignoring exception handling in logic processing.

Solution: Implement exception handling mechanisms to ensure graceful error management.