Data JPA-Association Mapping

Posted On: 2023-03-26 14:48:03 Spring Boot

                               Example 1:(*...1) (@ManyToOne) Employee---<>Dept (HAS-A)

1.Models Class (Employee)
package in.nareshit.raghu.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name="emptab")
public class Employee {
	@Id
	@Column(name="eid")
	private Integer empId;
	@Column(name="ename")
	private String empName;
	@Column(name="esal")
	private Double empSal;
	
	@ManyToOne
	@JoinColumn(name="didFk")
	private Dept dob; //HAS-A
	
} 
2.Models Class (Dept) 
package in.nareshit.raghu.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name="depttab")
public class Dept {
	@Id
	@Column(name="did")
	private Integer deptId;
	@Column(name="dcode")
	private String deptCode;
	@Column(name="dadmin")
	private String deptAdmin;
}

3. Dept Repository
package in.nareshit.raghu.repo;

import org.springframework.data.jpa.repository.JpaRepository;

import in.nareshit.raghu.model.Dept;

public interface DeptRepository 
	extends JpaRepository<Dept, Integer> {

}
4.Employee Repository
package in.nareshit.raghu.repo;

import org.springframework.data.jpa.repository.JpaRepository;

import in.nareshit.raghu.model.Employee;

public interface EmployeeRepository 
	extends JpaRepository<Employee, Integer> {

}

5. Runner class
package in.nareshit.raghu.runner;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

import in.nareshit.raghu.model.Dept;
import in.nareshit.raghu.model.Employee;
import in.nareshit.raghu.repo.DeptRepository;
import in.nareshit.raghu.repo.EmployeeRepository;

@Component
public class DataInertRunner implements CommandLineRunner {

	@Autowired
	private DeptRepository drepo;

	@Autowired
	private EmployeeRepository erepo;
	
	public void run(String... args) throws Exception {
		Dept d1 = new Dept(10,"DEV","SANJAY");
		drepo.save(d1);
		
		Employee e1 = new Employee(1, "A", 2.2, d1);
		Employee e2 = new Employee(2, "B", 3.2, d1);
		Employee e3 = new Employee(3, "C", 4.3, d1);
		
		erepo.save(e1);
		erepo.save(e2);
		erepo.save(e3);	
	}
}



                         Example 2:(1...*) (@OneToMany) Product---<>Model(HAS-A)
1. Model classes 
package in.nareshit.raghu.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name="modeltab")
public class Model {
	@Id
	@Column(name="mid")
	private Integer modId;
	@Column(name="mcode")
	private String modCode;
	@Column(name="mcolor")
	private String modColor;
	@Column(name="mcost")
	private Double modCost;
}
2. Product Class
package in.nareshit.raghu.model;

import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name="prodtab")
public class Product {
	@Id
	@Column(name="pid")
	private Integer prodId;
	@Column(name="pcode")
	private String prodCode;
	@Column(name="pvendor")
	private String vendor;
	
	@OneToMany
	@JoinColumn(name="midFk")
	private Set mobs; //HAS-A
	
}

3. Model Interface
package in.nareshit.raghu.repo;

import org.springframework.data.jpa.repository.JpaRepository;

import in.nareshit.raghu.model.Model;

public interface ModelRepository 
	extends JpaRepository<Model, Integer>
{

}
4. Product Repositpry
package in.nareshit.raghu.repo;

import org.springframework.data.jpa.repository.JpaRepository;

import in.nareshit.raghu.model.Product;

public interface ProductRepository 
	extends JpaRepository<Product, Integer>
{

}

5. Runner class
package in.nareshit.raghu.runner;

import java.util.Set;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

import in.nareshit.raghu.model.Model;
import in.nareshit.raghu.model.Product;
import in.nareshit.raghu.repo.ModelRepository;
import in.nareshit.raghu.repo.ProductRepository;

@Component
public class TestDataInertRunner implements CommandLineRunner {
	@Autowired
	private ModelRepository mrepo;

	@Autowired
	private ProductRepository prepo;
	
	public void run(String... args) throws Exception {
		Model m1 = new Model(105, "M34","RED", 5200.0);
		Model m2 = new Model(106, "K45","BLUE", 5400.0);
		Model m3 = new Model(107, "YT9","PINK", 5900.0);

		mrepo.save(m1);
		mrepo.save(m2);
		mrepo.save(m3);
		
		Product p1 = new Product(10, "S-MOBILE", "SANUI", 
				Set.of(m1,m2,m3));
		prepo.save(p1);
		
	}
}
                          

                             Example 3:(*...*) (@ManyToMany) Student---<>Course (HAS-A)

1. Models (Course)
package in.nareshit.raghu.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name="crstab")
public class Course {
	@Id
	@Column(name="cid")
	private Integer crsId;
	@Column(name="cname")
	private String crsName;
	@Column(name="cfee")
	private Double crsFee;
}
2.Model (Student)
package in.nareshit.raghu.model;

import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name="stdtab")
public class Student {
	@Id
	@Column(name="sid")
	private Integer stdId;
	@Column(name="sname")
	private String stdName;
	@Column(name="smail")
	private String stdEmail;
	
	@ManyToMany
	@JoinTable(
			name="stdcrstab",
			joinColumns = @JoinColumn(name="sidFk"),
			inverseJoinColumns = @JoinColumn(name="cidFk")
			)
	private Set cob; //HAS-A
	
	
}

3. Repository (Student) 
package in.nareshit.raghu.repo;
import org.springframework.data.jpa.repository.JpaRepository;
import in.nareshit.raghu.model.Student;
public interface StudentRepository 
	extends JpaRepository<Student, Integer> {

}
4.Repository (Course)
package in.nareshit.raghu.repo;
import org.springframework.data.jpa.repository.JpaRepository;
import in.nareshit.raghu.model.Course;
public interface CourseRepository 
	extends JpaRepository<Course, Integer> {

}

5. Runner class
package in.nareshit.raghu.runner;

import java.util.Set;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

import in.nareshit.raghu.model.Course;
import in.nareshit.raghu.model.Student;
import in.nareshit.raghu.repo.CourseRepository;
import in.nareshit.raghu.repo.StudentRepository;

@Component
public class DataInsertRunner implements CommandLineRunner {

	@Autowired
	private StudentRepository srepo;
	@Autowired
	private CourseRepository crepo;
	
	public void run(String... args) throws Exception {
		Course c1 = new Course(50, "CoreJava", 500.0);
		Course c2 = new Course(51, "SpringBoot", 600.0);
		Course c3 = new Course(52, "Microservices", 800.0);
		crepo.save(c1);
		crepo.save(c2);
		crepo.save(c3);
		Student s1 = new Student(5, "AJAY", "aj@gm.com", Set.of(c1,c2));
		Student s2 = new Student(6, "SYED", "sy@gm.com", Set.of(c2,c3));
		srepo.save(s1);
		srepo.save(s2);		
	}
}

                         Example 34(1...1) (@ManyToOne) Employee---<>Profile (HAS-A) 

1. Model
package in.nareshit.raghu.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name="profiletab")
public class Profile {
	@Id
	@Column(name="prid")
	private Integer profId;
	@Column(name="prcode")
	private String profCode;
	@Column(name="pexp")
	private Double profExp;
	@Column(name="ppack")
	private Double profPack;
}

-----
package in.nareshit.raghu.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name="emptab")
public class Employee {
	@Id
	@Column(name="eid")
	private Integer empId;
	@Column(name="ename")
	private String empName;
	@Column(name="edsg")
	private String empDesg;
	
	@ManyToOne
	@JoinColumn(name="pidFk",unique = true) //no duplicates 
	//@JoinColumn(name="pidFk",unique = true,nullable = false) //no null values even
	private Profile pob;//HAS-A
	
}

2. Repository Interface
package in.nareshit.raghu.repo;

import org.springframework.data.jpa.repository.JpaRepository;

import in.nareshit.raghu.model.Employee;

public interface EmployeeRepository 
extends JpaRepository<Employee, Integer> {

}
-------
package in.nareshit.raghu.repo;

import org.springframework.data.jpa.repository.JpaRepository;

import in.nareshit.raghu.model.Profile;

public interface ProfileRepository 
extends JpaRepository<Profile, Integer> {

}

3.Runner class
package in.nareshit.raghu.runner;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

import in.nareshit.raghu.model.Employee;
import in.nareshit.raghu.model.Profile;
import in.nareshit.raghu.repo.EmployeeRepository;
import in.nareshit.raghu.repo.ProfileRepository;

@Component
public class DataInertRunner 
	implements CommandLineRunner
{
	@Autowired
	private ProfileRepository prepo;
	
	@Autowired
	private EmployeeRepository erepo;

	public void run(String... args) throws Exception {
		Profile p1 = new Profile(10, "PER", 8.5, 15.9);
		Profile p2 = new Profile(11, "PET", 5.5, 10.6);
		Profile p3 = new Profile(12, "PTH", 8.0, 12.0);
		
		prepo.save(p1);
		prepo.save(p2);
		prepo.save(p3);
		
		Employee e1 = new Employee(1, "SAM", "DEV", p1);
		Employee e2 = new Employee(2, "SYED", "BA", p2);
		Employee e3 = new Employee(3, "JAI", "QA", p3);
		
		erepo.save(e1);
		erepo.save(e2);
		erepo.save(e3);
		
	}
}