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In this tutorial we will use JPA's @EmbeddedId Annotation to create Composite Primary Key from name and age.
@EmbeddedId hides Primary Key Properties from the Entity so we can't use @RequestBody to map JSON Properties.
Application Schema [Results]
Spring Boot Starters
GROUP
DEPENDENCY
DESCRIPTION
Web
Spring Web
Enables @Controller, @RequestMapping and Tomcat Server
SQL
Spring Data JPA
Enables @Entity and @Id
SQL
H2 Database
Enables in-memory H2 DB
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We will create PersonId Class to hold Properties from which Composite Primary Key will be created.
Inside PersonEntity we will use @EmbeddedId to specify that PersonId Class should be used as Id.
inside PersonRepository we also need to specify that PersonId Class should be used as Id.
PersonId.java
@Embeddable
public class PersonId implements Serializable {
private String name;
private Integer age;
PersonEntity.java
@EmbeddedId
public PersonId personId;
PersonRepository.java
public interface PersonRepository extends CrudRepository<PersonEntity, PersonId> { }
MyController
http://localhost:8080/AddPersons
addPersons()
PersonEntity
PersonId
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Create Project: entity_entity (add Spring Boot Starters from the table)
Edit File: application.properties (specify H2 DB name & enable H2 Web Console)
Create Package: entities (inside main package)
– Create Class: PersonId.java (inside package entities)
– Create Class: PersonEntity.java (inside package entities)
Create Package: repositories (inside main package)
– Create Interface: PersonRepository.java (inside package repositories)
Create Package: controllers (inside main package)
– Create Class: MyController.java (inside package controllers)
application.properties
# H2 DATABASE
spring.datasource.url = jdbc:h2:mem:testdb
spring.h2.console.enabled = true
PersonId.java
package com.ivoronline.springboot_db_primarykey_embeddedid.entities;
import javax.persistence.Embeddable;
import java.io.Serializable;
@Embeddable
public class PersonId implements Serializable {
//PROEPRTIES FOR COMPOSITE PRIMARY KEY
private String name;
private Integer age;
//REQUIERED NO ARGS CONSTRUCTOR
public PersonId() {}
//CONSTRUCTOR FOR findById(BookId)
public PersonId(String name, Integer age) {
this.name = name;
this.age = age;
}
}
PersonEntity.java
package com.ivoronline.springboot_db_primarykey_embeddedid.entities;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
@Entity
public class PersonEntity {
//COMPOSITE PRIMARY KEY
@EmbeddedId
public PersonId personId;
//OTHER PROPERTIES
public String book;
}
PersonRepository.java
package com.ivoronline.springboot_primarykey_idclass.respositories;
import com.ivoronline.springboot_primarykey_idclass.entities.PersonEntity;
import com.ivoronline.springboot_primarykey_idclass.entities.PersonId;
import org.springframework.data.repository.CrudRepository;
public interface PersonRepository extends CrudRepository<PersonEntity, PersonId> { }
MyController.java
package com.ivoronline.springboot_db_primarykey_embeddedid.controllers;
import com.ivoronline.springboot_db_primarykey_embeddedid.entities.PersonEntity;
import com.ivoronline.springboot_db_primarykey_embeddedid.entities.PersonId;
import com.ivoronline.springboot_db_primarykey_embeddedid.respositories.PersonRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
public class MyController {
@Autowired PersonRepository personRepository;
//===================================================================
// ADD PERSONS
//===================================================================
@ResponseBody
@RequestMapping("/AddPersons")
public String addPersons() {
//CREATE BOOK1
PersonEntity personEntity1 = new PersonEntity();
personEntity1.personId = new PersonId("John", 20);
personEntity1.book = "Book about dogs";
//CREATE BOOK2
PersonEntity personEntity2 = new PersonEntity();
personEntity1.personId = new PersonId("John", 50);
personEntity2.book = "Book about cats";
//STORE BOOKS
personRepository.save(personEntity1);
personRepository.save(personEntity2);
//RETURN SOMETHING TO BROWSER
return "Persons added to DB";
}
//===================================================================
// GET PERSON
//===================================================================
@ResponseBody
@RequestMapping("/GetPerson")
public PersonEntity getPerson() {
PersonEntity personEntity = personRepository.findById(new PersonId("John", 20)).get();
return personEntity;
}
}
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http://localhost:8080/AddPersons
http://localhost:8080/GetPerson
Open H2 Console: http://localhost:8080/h2-console - Connect - PERSON_ENTITY - Run
Application Structure
pom.xml
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
</dependencies>