Hibernate embedded and embeddable entities

Posted By : Amit Mishra | 14-Jan-2021

In this post, we are going to talk about two different JPA annotations: @Embedded and @Embeddable. You can use @Embedded and @Embeddable whenever you want to have separate values common for more than one Entities. For example, you have an Employee and Staff Domain. In both domains, you want to add a few constraints and you don't want to repeat the code. You can define a separate domain for address and you can easily use that address with Staff Domain as well as Employee Domain.

 

@Embeddable is a composition of values. For example, we might have a Name class that is a composition of first-name and last-name, or an Address class that is a composition of street, city, postal code, etc. Which can be later on used in multiple Entities to be used as Embeddable Objects.

 

Let's Start with our Employee Class

package com.example.demo; 

import javax.persistence.Embedded; 
import javax.persistence.Entity; 
import javax.persistence.GeneratedValue; 
import javax.persistence.GenerationType; 
import javax.persistence.Id; 
@Entity 
public class Employee {
 
     @Id @GeneratedValue(strategy = GenerationType.IDENTITY) 
     private Long id;
     private String name; 
     private String mobile; 
     @Embedded private Address employeeAddress; 

     //Standard setters and getters

}

The @Embedded annotation tells this to hibernate that it's embedded content and hibernate will include all the columns available in the class which we're embedding. Also, It will not create a separate table it will expand the current table.

 

Also Read: Reading a CSV file in java

 

Our Staff class

 
@Entity 
public class Staff { 
    
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private Long id; 
    private String name; 
    private String department; 
    @Embedded private Address staffAddress; 

   //Standard setters and getters

}

 

The Embeddable Content  


@Embeddable 
public class Address { 

     private String addressLine1; 
     private String City; 
     private int zipCode; 

     //Standard setters and getters

}

 

Also Read: How To Integrate A 3rd Party API In Drupal

 

Test the code

 

@Test
public static void performOperation() {
   //Performing Employee save operation 
   Employee em = new Employee("Name", "mobile", new Address("line1", "city", 445121));
   erepo.save(em); 

   Employee saved = erepo.findByName("Name");

   Assert.equals(em, saved);
 }

 

The Application Logs

 

//Table creation Hibernate: 

drop table if exists employee CASCADE
Hibernate: drop table if exists staff CASCADE 
Hibernate: create table employee (id bigint generated by default as identity, city varchar(255), address_line1 varchar(255), zip_code integer not null, mobile varchar(255), name varchar(255), primary key (id)) 
Hibernate: create table staff (id bigint generated by default as identity, department varchar(255), name varchar(255), city varchar(255), address_line1 varchar(255), zip_code integer not null, primary key (id)) 

//Insert Data 
Hibernate: insert into employee (id, city, address_line1, zip_code, mobile, name) values (null, ?, ?, ?, ?, ?) 
Hibernate: select employee0_.id as id1_0_, employee0_.city as city2_0_, employee0_.address_line1 as address_3_0_, employee0_.zip_code as zip_code4_0_, employee0_.mobile as mobile5_0_, employee0_.name as name6_0_ from employee employee0_ where employee0_.name=? 

Thank you so much for giving your time to read this post.

 

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About Author

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Amit Mishra

Amit is a spring web developer. He has good knowledge of Spring Cloud, Spring Boot, Spring MVC, Hibernate, and some template engines like jsp and thymleaf.

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