[Spring] JPA로 오브젝트 업데이트

JPA를 사용해서 Objects 업데이트하기

• Hibernate/JPA CRUD (7)

Update a Student

Update last name for all students

Development Process

1. Add new method to DAO interface
2. Add new method to DAO implementation
3. Update main app

Step 1: Add new method to DAO interface

public interface StudentDAO {
	...
	
    void update(Student theStudent);  
}

Step2: Define DAO implementation

@Repository  
public class StudentDAOImpl implements StudentDAO{  
  
    // define field for entity manager  
    private EntityManager entityManager;  
	  ...
	  
    @Override  
    @Transactional    // <- Because we are performing an update
    public void update(Student theStudent) {  
        entityManager.merge(theStudent);  
  
    }  
}

Step 3: Update main app

@SpringBootApplication  
public class CruddemoApplication {  
  
....
  
   @Bean  
   public CommandLineRunner commandLineRunner(StudentDAO studentDAO){  
      return runner-> {  
   
      updateStudent(studentDAO);  
  
      };  
   }  
  
   private void updateStudent(StudentDAO studentDAO) {  
  
      // retrieve student based on the id: primary key  
      int studentId = 1;  
      System.out.println("Getting student with id: " + studentId);  
      Student myStudent = studentDAO.findById(studentId);  
  
      // change first name to "Scooby"  
      System.out.println("Updating student ,,,");  
      myStudent.setFirstName("Scooby");  
  
      // update the student  
      studentDAO.update(myStudent);  
  
      // display the updated student  
      System.out.println("Updated a student: " + myStudent);  
   }