JPA One To Many example with Hibernate and Spring Boot

in this article we will cover one to many relationship in spring boot.

employ has many Addresses in uni-direction relationships. JPA One To Many with Hibernate in Spring Boot is a way to map a one-to-many relationship between two entities in a database. The one-to-many relationship means that one row in a table can be associated with multiple rows in another table. JPA One To Many example with Hibernate and Spring Boot

In this tutorial, I will show you how to implement Spring JPA One-To-Many mapping with Hibernate in a Spring Boot CRUD example using annotation. You’ll know: JPA One To Many examples with Hibernate and Spring Boot

• How to configure Spring Data, JPA, and Hibernate to work with Database
• How to define Data Models and Repository interfaces for JPA One-To-Many relationship
• Way to use Spring JPA to interact with Database for One-To-Many association
• Way to create Spring Rest Controller to process HTTP requests

Employ Entity Class 

package com.onetomany.demoonetomany.Employ;

import com.onetomany.demoonetomany.Address.Address;

import javax.persistence.*;
import java.util.List;

@Entity
public class Employ {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    int id;
    String name;
    String status;


    @OneToMany(cascade =CascadeType.ALL)
    @JoinColumn
    List<Address> addressList;


    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public List<Address> getAddressList() {
        return addressList;
    }

    public void setAddressList(List<Address> addressList) {
        this.addressList = addressList;
    }

    public Employ(String name, String status, List<Address> addressList) {
        this.name = name;
        this.status = status;
        this.addressList = addressList;
    }

    public Employ(int id, String name, String status, List<Address> addressList) {
        this.id = id;
        this.name = name;
        this.status = status;
        this.addressList = addressList;
    }

    public Employ() {
    }
}

In the Department entity, we have a One-to-Many relationship with Employee, specified by the @OneToMany annotation. The mappedBy attribute indicates that the relationship is mapped by the department field in the Employee entity.

In the Employee entity, we have a Many-to-One relationship with Department, specified by the @ManyToOne annotation. The @JoinColumn annotation specifies the foreign key column in the employees table that references the departments table.

Employ Repository Class 

package com.onetomany.demoonetomany.Employ;

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

public interface EmployRepository extends JpaRepository<Employ,Integer> {

}

Address Entity Class

package com.onetomany.demoonetomany.Address;

import com.onetomany.demoonetomany.Country.Country;

import javax.persistence.*;
import java.util.List;

@Entity
public class Address {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    int id;
    String addressName;

    @OneToMany(cascade = CascadeType.ALL)
            @JoinColumn
    List<Country> country;

    public List<Country> getCountry() {
        return country;
    }

    public void setCountry(List<Country> country) {
        this.country = country;
    }

    public String getAddressName() {
        return addressName;
    }

    public void setAddressName(String addressName) {
        this.addressName = addressName;
    }
}

Address Repository Class

package com.onetomany.demoonetomany.Address;

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

@Repository
public interface Addressrepository extends JpaRepository<Address,Integer> {


}

Controller Class 

package com.onetomany.demoonetomany.API;

import com.onetomany.demoonetomany.Address.Address;
import com.onetomany.demoonetomany.Address.Addressrepository;
import com.onetomany.demoonetomany.Comment.Comment;
import com.onetomany.demoonetomany.Comment.CommentRepository;
import com.onetomany.demoonetomany.Country.Country;
import com.onetomany.demoonetomany.Country.CountryRepository;
import com.onetomany.demoonetomany.Employ.Employ;
import com.onetomany.demoonetomany.Employ.EmployRepository;
import com.onetomany.demoonetomany.Post.Post;
import com.onetomany.demoonetomany.Post.PostRepository;
import com.onetomany.demoonetomany.Request.PostRequest;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.List;

@RestController
public class Controller {
    @Autowired
    EmployRepository employRepository;
    @Autowired
    Addressrepository addressrepository;
    @Autowired
    CountryRepository countryRepository;

    @Autowired
    PostRepository postRepository;
  @Autowired
    CommentRepository commentRepository;


    @PostMapping("/add/employ")
    public Employ addemploy(@RequestBody Employ employ){
        List<Country> countryList=new ArrayList<>();
        Country country=new Country();
        country.setStatename("Punjab");
        country.setCode(12340);
        countryList.add(country);

        List<Address> addressList=new ArrayList<>();
        Address address=new Address();
        address.setAddressName("sheikh umad kohna kasur");
        address.setCountry(countryList);
     addressList.add(address);
        Employ employ1=new Employ();
        employ1.setName("Muhammad Waseem haider");
        employ1.setStatus("Mariage");
        employ1.setAddressList(addressList);
    return   employRepository.save(employ1);






    }

    @GetMapping("/list/employ")
    private List<Employ> getAllBooks()
    {
        return employRepository.findAll();
    }

  

}


Application.Properties file

#spring.datasource.url=jdbc:mysql://localhost:3306/waseem
#spring.datasource.username=root
#spring.datasource.password=
#and other credentials

spring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.hibernate.ddl-auto=update
spring.datasource.driverClassName=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/blog
spring.datasource.username=root
spring.datasource.password=

Main Class

package com.onetomany.demoonetomany;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.util.ArrayList;
import java.util.List;

@SpringBootApplication
public class DemoonetomanyApplication {

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

   }

}

Get All List of Employ

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