One-to-Many Update

Operasi update pada kasus relasi Classes dan Student, akan menggunakan methode merge() dan mekanisme Dirty Checking otomatis yang memungkinkan pembaruan data secara efisien tanpa harus menulis query SQL manual, sekaligus memastikan perubahan tersinkronisasi secara dua arah (bi-directional).

Pembahasan materi update ini akan dibahas dari sisi parrent(Classes) dan update dari sisi child(Student).

1️⃣ Entity Parrent: Classes.java

Ubah fetch type menjadi Lazy fetch = FetchType.LAZY:

@Entity
@Table(name = "classes")
public class Classes {

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private Integer id;
	
	@Column(name = "class_name")
	private String className;
	
	@OneToOne(cascade = {CascadeType.DETACH, CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH})
	@JoinColumn(name = "teacher_id")
	private Teacher teacher;
	
	@OneToMany(
		mappedBy = "classes",
		fetch = FetchType.LAZY,
		cascade = {CascadeType.DETACH, CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH})
	List<Student> students = new ArrayList<>();

	// Setter & Getter

}

2️⃣ Entity Child: Student.java

Sisi @ManyToOne secara default bersifat EAGER, pada kasus ini kita tidak perlu mengubahnya kecuali kita ingin menjadikannya LAZY.

@Entity
@Table(name = "student")
public class Student {

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private Integer id;
	
	@Column(name = "first_name")
	private String firstName;
	
	@Column(name = "last_name")
	private String lastName;
	
	@ManyToOne(cascade = {CascadeType.DETACH, CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH})
	@JoinColumn(name = "class_id")
	private Classes classes;
	
	// Setter & Getter

}

3️⃣ Update Parrent Classes

🛢️ Repository / DAO

• Menambahkan method baru pada interface DAO dengan menambahkan method updateClasses(Classes classes):

public interface SchoolDAO {

	void saveClasses(Classes classes);
	
	Classes findClassById(Integer id);
	
	void deleteClassesById(Integer id);
	
	Teacher findTeacherById(Integer id);
	
	void deleteTeacherById(Integer id);
	
	List<Student> findStudentByClassId(Integer id);
	
	Classes findClassesByIdJoinFetch(Integer id);
	
	void updateClasses(Classes classes);
	
}

• Implementasi DAO:

@Repository
public class SchoolDAOImpl implements SchoolDAO {

	private EntityManager entityManager;
	
	public SchoolDAOImpl(EntityManager entityManager) {
		this.entityManager = entityManager;
	}

	@Override
	@Transactional
	public void updateClasses(Classes classes) {
		entityManager.merge(classes);	
	}

	// Implementasi method Lainnya

}

▶️ Main Class

• Pada main class application kita akan mengubah data Classes yang memiliki id 3:

@SpringBootApplication
public class Application {

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}

	// Bean ini akan dieksekusi di command line
	@Bean
	public CommandLineRunner commandLineRunner(SchoolDAO dao) {
		return runner -> {
			
			updateClasses(dao);
			
		};
	}

	private void updateClasses(SchoolDAO dao) {
		int id = 3;
		
		Classes classes = dao.findClassesByIdJoinFetch(id);
		classes.setClassName("Kelas 12");
		dao.updateClasses(classes);		
	}
}

• Output pada Hibernate SQL:

Hibernate: select c1_0.id,c1_0.class_name,s1_0.class_id,s1_0.id,s1_0.first_name,s1_0.last_name,t1_0.id,t1_0.first_name,t1_0.last_name from classes c1_0 join student s1_0 on c1_0.id=s1_0.class_id join teacher t1_0 on t1_0.id=c1_0.teacher_id where c1_0.id=?
Hibernate: select c1_0.id,c1_0.class_name,t1_0.id,t1_0.first_name,t1_0.last_name,s1_0.class_id,s1_0.id,s1_0.first_name,s1_0.last_name from classes c1_0 left join teacher t1_0 on t1_0.id=c1_0.teacher_id left join student s1_0 on c1_0.id=s1_0.class_id where c1_0.id=?
Hibernate: update classes set class_name=?,teacher_id=? where id=?

• Cek perubahan dalam database dengan id 3.

mysql> select * from classes;

+----+------------+------------+
| id | class_name | teacher_id |
+----+------------+------------+
|  3 | Kelas 12   |          2 |
+----+------------+------------+

4️⃣ Update Child Student

🛢️ Repository / DAO

• Menambahkan method baru pada interface DAO dengan menambahkan method findStudentById(Integer id) dan updateStudent(Student student) untuk menghandle update data Student:

public interface SchoolDAO {

	void saveClasses(Classes classes);
	
	Classes findClassById(Integer id);
	
	void deleteClassesById(Integer id);
	
	Teacher findTeacherById(Integer id);
	
	void deleteTeacherById(Integer id);
	
	List<Student> findStudentByClassId(Integer id);
	
	Classes findClassesByIdJoinFetch(Integer id);
	
	void updateClasses(Classes classes);

	Student findStudentById(Integer id);
	
	void updateStudent(Student student);
	
}

• Implementasi DAO:

@Repository
public class SchoolDAOImpl implements SchoolDAO {

	private EntityManager entityManager;
	
	public SchoolDAOImpl(EntityManager entityManager) {
		this.entityManager = entityManager;
	}

	// handle update data Classes
	@Override
	@Transactional
	public void updateClasses(Classes classes) {
		entityManager.merge(classes);	
	}

	// handle update data Student
	@Override
	@Transactional(readOnly = true)
	public Student findStudentById(Integer id) {
		return entityManager.find(Student.class, id);
	}
	
	@Override
	@Transactional
	public void updateStudent(Student student) {
		entityManager.merge(student);
	}

	// Implementasi method Lainnya

}

▶️ Main Class

• Pada main class application kita akan mengubah data Student yang memiliki id 9:

@SpringBootApplication
public class Application {

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}

	// Bean ini akan dieksekusi di command line
	@Bean
	public CommandLineRunner commandLineRunner(SchoolDAO dao) {
		return runner -> {
			
			updateStudent(dao);

		};
	}

	private void updateStudent(SchoolDAO dao) {
		int id = 9;
		
		Student student = dao.findStudentById(id);
		student.setFirstName("Rock");
		student.setLastName("Lee");
		dao.updateStudent(student);
	}
}

• Output pada Hibernate SQL:

Hibernate: select s1_0.id,c1_0.id,c1_0.class_name,t1_0.id,t1_0.first_name,t1_0.last_name,s1_0.first_name,s1_0.last_name from student s1_0 left join classes c1_0 on c1_0.id=s1_0.class_id left join teacher t1_0 on t1_0.id=c1_0.teacher_id where s1_0.id=?
Hibernate: select s1_0.id,c1_0.id,c1_0.class_name,t1_0.id,t1_0.first_name,t1_0.last_name,s1_0.first_name,s1_0.last_name from student s1_0 left join classes c1_0 on c1_0.id=s1_0.class_id left join teacher t1_0 on t1_0.id=c1_0.teacher_id where s1_0.id=?
Hibernate: select s1_0.class_id,s1_0.id,s1_0.first_name,s1_0.last_name from student s1_0 where s1_0.class_id=?
Hibernate: update student set class_id=?,first_name=?,last_name=? where id=?

• Cek perubahan dalam database, dalam tabel Student data dengan id 9 sudah berubah.

mysql> select * from student;
+----+------------+-----------+----------+
| id | first_name | last_name | class_id |
+----+------------+-----------+----------+
|  7 | Uzumaki    | Naruto    |        3 |
|  8 | Uciha      | Sazuke    |        3 |
|  9 | Rock       | Lee       |        3 |
+----+------------+-----------+----------+

info

Source Code: https://github.com/TimposuLabs/belajar-springboot-jpa-hibernate-advance/tree/main/08-hibernate-one-to-many-update