Collection Mapping Spring Data Jpa | JPA Collection Mapping

 Collection Mapping Spring Data Jpa

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Directory Structure

application.properties

#datasource

spring.datasource.url=jdbc:mysql://localhost:3306/new

spring.datasource.username=root

spring.datasource.password=root

#jpa

spring.jpa.hibernate.ddl-auto=create

spring.jpa.show-sql=true

spring.jpa.properties.hibernate.enable_lazy_load_no_trans=true

SpringBootDataJpaCollectionMappingApplication 

package com.app;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication

public class SpringBootDataJpaCollectionMappingApplication {

public static void main(String[] args) {

SpringApplication.run(SpringBootDataJpaCollectionMappingApplication.class, args);

}

}

Employee 

package com.app.entity;

import java.util.List;

import java.util.Map;

import java.util.Set;

import javax.persistence.CollectionTable;

import javax.persistence.Column;

import javax.persistence.ElementCollection;

import javax.persistence.Entity;

import javax.persistence.Id;

import javax.persistence.JoinColumn;

import javax.persistence.MapKeyColumn;

import javax.persistence.OrderColumn;

import javax.persistence.Table;

import lombok.AllArgsConstructor;

import lombok.Data;

import lombok.NoArgsConstructor;

@Data

@AllArgsConstructor

@NoArgsConstructor

@Entity

@Table(name = "emptab")

public class Employee {

@Id

@Column(name = "eid")

private Integer empId;

@Column(name = "ename")

private String empName;

@ElementCollection

@CollectionTable(

name = "emp_friends",//child tab name

joinColumns = @JoinColumn(name="eid")//FK col name

)

@OrderColumn(name = "pos")

@Column(name = "frd_name")

private List<String> friends;

@ElementCollection

@CollectionTable(

name = "emp_cards",//child tab name

joinColumns = @JoinColumn(name="eid")//FK col name

)

@MapKeyColumn(name = "cname")

@Column(name = "cno")

private Map<String,String> cards;

@ElementCollection

@CollectionTable(

name = "emp_proj",//child tab name

joinColumns = @JoinColumn(name="eid")//FK col name

)

@Column(name = "projName")

private Set<String> projects;

}

EmployeeRepository 

package com.app.repo;

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

import com.app.entity.Employee;

public interface EmployeeRepository extends JpaRepository<Employee, Integer>{

}

TestRunner 

package com.app.runner;

import java.util.Arrays;

import java.util.List;

import java.util.Map;

import java.util.Set;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.CommandLineRunner;

import org.springframework.stereotype.Component;

import com.app.entity.Employee;

import com.app.repo.EmployeeRepository;

@Component

public class TestRunner implements CommandLineRunner{

@Autowired

private EmployeeRepository repo;

@Override

public void run(String... args) throws Exception {

//friends names

List<String> list = Arrays.asList("jhon","angela");

//cards info

Map<String,String> map = Map.of("aadhar","1234","pan","MK34");

//proj names

Set<String> set = Set.of("p1","p2");

repo.save(new Employee(101,"sam",list,map,set));

repo.findAll().forEach(System.out::println);

}

}