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Explanation

DTO (Data Transfer Object) is used to transfer data between the client and server. Instead of exposing entity classes directly, APIs send and receive DTOs.

Code:

public class StudentDTO {
    private String name;
    private String email;

    // Getters and Setters
}

Explanation

Entity classes represent database tables, while DTO classes represent API request and response models. This separates persistence logic from API design.

Code:

@Entity
public class Student {
    @Id
    private Long id;
    private String name;
    private String email;
    private String password;
}

Explanation

Convert an Entity to a DTO before returning data to clients. This prevents exposing sensitive fields such as passwords.

Code:

StudentDTO dto = new StudentDTO();
dto.setName(student.getName());
dto.setEmail(student.getEmail());

Explanation

Controllers should receive DTO objects instead of Entity objects. The service layer converts DTOs into Entities before saving them.

Code:

@PostMapping
public StudentDTO createStudent(@RequestBody StudentDTO dto) {
    return dto;
}

Explanation

DTOs improve security, maintainability, and API flexibility. Libraries like ModelMapper can automatically convert between Entities and DTOs.

Code:

@Autowired
private ModelMapper modelMapper;

StudentDTO dto = modelMapper.map(student, StudentDTO.class);