Spring Boot 2 - CRUD example using JPA and MySQL database

package com.example.demo;

​

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

​

@SpringBootApplication

public class DemoApplication {

​

    public static void main(String[] args) {

        SpringApplication.run(DemoApplication.class, args);

    }

}

package com.example.demo;

​

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

import org.springframework.http.MediaType;

import org.springframework.http.ResponseEntity;

import org.springframework.stereotype.Controller;

import org.springframework.transaction.annotation.Transactional;

import org.springframework.web.bind.annotation.*;

​

import java.util.List;

import java.util.Optional;

​

@Controller

public class UsersController {

​

    @Autowired

    private UsersRepository usersRepository;

​

    // http://localhost:8080/api/users

    //

    @GetMapping(

            value = "/api/users",

            produces = MediaType.APPLICATION_JSON_VALUE

    )

    @Transactional(readOnly = true)

    public ResponseEntity<List<UserEntity>> getUsers() {

       return  ResponseEntity.ok(this.usersRepository.findAll());

    }

​

    // http://localhost:8080/api/users/1

    //

    @GetMapping(

            value = "/api/users/{id}",

            produces = MediaType.APPLICATION_JSON_VALUE

    )

    @Transactional(readOnly = true)

    public ResponseEntity<UserEntity> getUser(@PathVariable("id") Long userId) {

        return ResponseEntity.of(this.usersRepository.findById(userId));

    }

​

    // POST http://localhost:8080/api/user/create

    // echo '{"name":"john","email":"john@email.com"}' | curl -X POST -H "Content-Type: application/json" -d @- http://localhost:8080/api/user/create

    //

    @PostMapping(

            value = "/api/user/create",

            consumes = MediaType.APPLICATION_JSON_VALUE,

            produces = MediaType.APPLICATION_JSON_VALUE

    )

    @Transactional

    public ResponseEntity<UserEntity> createUser(@RequestBody UserEntity userEntity) {

        return ResponseEntity.ok(this.usersRepository.save(userEntity));

    }

​

    // POST http://localhost:8080/api/users/1/update

    // echo '{"name":"chris","email":"chris@email.com"}' | curl -X POST -H "Content-Type: application/json" -d @- http://localhost:8080/api/users/1/update

    //

    @PostMapping(

            value = "/api/users/{id}/update",

            consumes = MediaType.APPLICATION_JSON_VALUE,

            produces = MediaType.APPLICATION_JSON_VALUE

    )

    @Transactional

    public ResponseEntity<UserEntity> updateUser(@PathVariable("id") Long userId, @RequestBody UserEntity newUserEntity) {

        Optional<UserEntity> foundUserOptional = this.usersRepository.findById(userId);

        if (foundUserOptional.isPresent()) {

            UserEntity foundUserEntity = foundUserOptional.get();

            foundUserEntity.setName(newUserEntity.getName());

            foundUserEntity.setEmail(newUserEntity.getEmail());

            this.usersRepository.save(foundUserEntity);

        }

        return ResponseEntity.of(foundUserOptional);

    }

​

    // http://localhost:8080/api/users/1/remove

    //

    @GetMapping(

            value = "/api/users/{id}/remove",

            produces = MediaType.APPLICATION_JSON_VALUE

    )

    @Transactional

    public ResponseEntity<UserEntity> removeUser(@PathVariable("id") Long userId) {

        Optional<UserEntity> foundUserOptional = this.usersRepository.findById(userId);

        if (foundUserOptional.isPresent()) {

            this.usersRepository.deleteById(userId);

        }

        return ResponseEntity.of(foundUserOptional);

    }

}

package com.example.demo;

​

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

import org.springframework.stereotype.Repository;

​

import java.util.List;

import java.util.Optional;

​

@Repository

public interface UsersRepository extends JpaRepository<UserEntity, Long> {

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    // Hint: use Intellij IDEA Ultimate to get very good intellisense for repositories

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    List<UserEntity> findAll();

    Optional<UserEntity> findById(Long id);

​

    // See also:

    //

    //     1. @Query annotation

    //     2. Specifications / JpaSpecificationExecutor

}

package com.example.demo;

​

import javax.persistence.*;

​

@Entity

@Table(name = "users")

public class UserEntity {

​

    @Id

    @GeneratedValue(strategy = GenerationType.IDENTITY)

    private long id;

​

    @Column(name = "name", nullable = false)

    private String name;

​

    @Column(name = "email", nullable = false)

    private String email;

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    public UserEntity() { }

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    public UserEntity(long id, String name, String email) {

        this.id = id;

        this.name = name;

        this.email = email;

    }

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    public long getId() {

        return this.id;

    }

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    public void setId(long id) {

        this.id = id;

    }

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    public String getName() {

        return this.name;

    }

​

    public void setName(String name) {

        this.name = name;

    }

​

    public String getEmail() {

        return this.email;

    }

​

    public void setEmail(String email) {

        this.email = email;

    }

}

db.host=localhost

db.port=3306

db.name=example_db

​

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

spring.datasource.url=jdbc:mysql://${db.host}:${db.port}/${db.name}?useUnicode=yes&characterEncoding=UTF-8&serverTimezone=UTC&character_set_server=utf8mb4

spring.datasource.username=root

spring.datasource.password=root

​

# May be required by Docker:

#

# spring.jpa.database-platform=org.hibernate.dialect.MySQLDialect

​

# spring.jpa.show-sql=true

# spring.jpa.hibernate.ddl-auto=update

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">

​

    <modelVersion>4.0.0</modelVersion>

​

    <parent>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-parent</artifactId>

        <version>2.6.5</version>

        <relativePath/> <!-- lookup parent from repository -->

    </parent>

​

    <groupId>com.example</groupId>

    <artifactId>demo</artifactId>

    <version>0.0.1-SNAPSHOT</version>

    <name>demo</name>

    <description>Demo project for Spring Boot</description>

​

    <properties>

        <java.version>1.8</java.version>

    </properties>

​

    <dependencies>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-web</artifactId>

        </dependency>

​

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-test</artifactId>

            <scope>test</scope>

        </dependency>

​

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-data-jpa</artifactId>

        </dependency>

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        <dependency>

            <groupId>mysql</groupId>

            <artifactId>mysql-connector-java</artifactId>

            <version>8.0.22</version>

        </dependency>

    </dependencies>

​

    <build>

        <plugins>

            <plugin>

                <groupId>org.springframework.boot</groupId>

                <artifactId>spring-boot-maven-plugin</artifactId>

            </plugin>

        </plugins>

    </build>

​

</project>

CREATE DATABASE `example_db`

​

​

CREATE TABLE `users` (

    `id` BIGINT(10) UNSIGNED NOT NULL AUTO_INCREMENT,

    `name` VARCHAR(100) NOT NULL,

    `email` VARCHAR(255) NOT NULL,

    PRIMARY KEY (`id`)

)

ENGINE=InnoDB;