Update Entity with Spring Data JPA in Spring Boot

On the Eclipse, create a Spring Boot project

Enter Project Information:

Name: LearnSpringBootWithRealApps
Group: com.demo
Artifact: LearnSpringBootWithRealApps
Description: Learn Spring Boot with Real Apps
Package: com.demo

Select the technologies and libraries to be used:

JPA
MySQL

Click Next button to show Site Information for project

Click Finish button to finish create Spring Boot project

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
						http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.demo</groupId>
	<artifactId>LearnSpringBootWithRealApps</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>LearnSpringBootWithRealApps</name>
	<description>Learn Spring Boot with Real Apps</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.10.RELEASE</version>
		<relativePath /> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>

		<!-- Spring Framework -->
		<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

		<!-- Spring Data JPA -->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>

		<!-- MySQL JDBC -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>

	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

Create a database with the name is learn_spring_boot_with_real_apps. This database have 1 table: Product table

--
-- Table structure for table `product`
--

CREATE TABLE `product` (
  `id` int(11) NOT NULL PRIMARY KEY AUTO_INCREMENT,
  `name` varchar(250) COLLATE utf8_unicode_ci NOT NULL,
  `price` decimal(10,1) NOT NULL,
  `quantity` int(11) NOT NULL,
  `description` text COLLATE utf8_unicode_ci NOT NULL,
  `photo` varchar(250) COLLATE utf8_unicode_ci NOT NULL,
  `featured` tinyint(1) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

--
-- Dumping data for table `product`
--

INSERT INTO `product` (`name`, `price`, `quantity`, `description`, `photo`, `featured`) VALUES('Mobile 1', '2.0', 2, 'description 1', 'thumb1.gif', 1);
INSERT INTO `product` (`name`, `price`, `quantity`, `description`, `photo`, `featured`) VALUES('Mobile 2', '1.0', 5, 'description 2', 'thumb2.gif', 1);
INSERT INTO `product` (`name`, `price`, `quantity`, `description`, `photo`, `featured`) VALUES('Mobile 3', '3.0', 9, 'description 3', 'thumb3.gif', 1);
INSERT INTO `product` (`name`, `price`, `quantity`, `description`, `photo`, `featured`) VALUES('Computer 1', '5.0', 12, 'description 4', 'thumb1.gif', 0);
INSERT INTO `product` (`name`, `price`, `quantity`, `description`, `photo`, `featured`) VALUES('Computer 2', '7.0', 5, 'description 5', 'thumb1.gif', 1);
INSERT INTO `product` (`name`, `price`, `quantity`, `description`, `photo`, `featured`) VALUES('Computer 3', '12.0', 2, 'description 6', 'thumb2.gif', 1);
INSERT INTO `product` (`name`, `price`, `quantity`, `description`, `photo`, `featured`) VALUES('Laptop 1', '3.0', 8, 'description 7', 'thumb2.gif', 0);
INSERT INTO `product` (`name`, `price`, `quantity`, `description`, `photo`, `featured`) VALUES('Laptop 2', '4.0', 11, 'description 8', 'thumb3.gif', 0);
INSERT INTO `product` (`name`, `price`, `quantity`, `description`, `photo`, `featured`) VALUES('Laptop 3', '2.0', 15, 'description 9', 'thumb2.gif', 1);

spring.datasource.url= jdbc:mysql://localhost:3306/learn_spring_boot_with_real_apps
spring.datasource.username=root
spring.datasource.password=123456

Create new package named com.demo.entities. In this package, create a entity class – Product.java, to represent the above table

package com.demo.entities;

import java.math.BigDecimal;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import java.io.Serializable;

@Entity
@Table(name = "product")
public class Product implements Serializable {

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private int id;

	@Column
	private String name;

	@Column
	private BigDecimal price;

	@Column
	private int quantity;

	@Column
	private String description;

	@Column
	private String photo;

	@Column
	private boolean featured;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

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

	public BigDecimal getPrice() {
		return price;
	}

	public void setPrice(BigDecimal price) {
		this.price = price;
	}

	public int getQuantity() {
		return quantity;
	}

	public void setQuantity(int quantity) {
		this.quantity = quantity;
	}

	public String getDescription() {
		return description;
	}

	public void setDescription(String description) {
		this.description = description;
	}

	public String getPhoto() {
		return photo;
	}

	public void setPhoto(String photo) {
		this.photo = photo;
	}

	public boolean isFeatured() {
		return featured;
	}

	public void setFeatured(boolean featured) {
		this.featured = featured;
	}

}

Create new package named com.demo.repositories. In this package create the ProductRepository interface implements from CrudRepository interface of Spring Data JPA that provides CRUD operations for an entity.

package com.demo.repositories;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import com.demo.entities.Product;

@Repository("productRepository")
public interface ProductRepository extends CrudRepository<Product, Integer> {

}

Open LearnSpringBootWithRealAppsApplication.java file in com.demo package, call methods from ProductRepository. To show result to console, this class need implements from CommandLineRunner

package com.demo;

import java.math.BigDecimal;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import com.demo.entities.Product;
import com.demo.repositories.ProductRepository;

@SpringBootApplication
public class LearnSpringBootWithRealAppsApplication implements CommandLineRunner {

	@Autowired
	ProductRepository productRepository;

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

	@Override
	public void run(String... arg0) throws Exception {

		System.out.println("Update product with Id is 12");
		Product product = productRepository.findOne(12);
		product.setName("New Name 1");
		product.setPrice(BigDecimal.valueOf(11));
		product.setFeatured(true);
		productRepository.save(product);
		System.out.println("Done");

	}
}

Update product with Id is 12
Done

I recommend you refer to the books below to learn more about the knowledge in this article:

Create Spring Boot Project

Configure pom.xml

Create Database

Structure of Product Table

Data of Product Table

Configure application.properties

Entities Class

Product.java

Create ProductRepository Interface

Structure of Spring Boot Project

Run Application

Output

References