Google Cloud SQL for MySQL + Spring Boot - Build REST CRUD APIs

In this section, we will learn how to build REST CRUD APIs with Spring Boot, and Google Cloud SQL for MySQL.


1.  A little bit of Background

Google Cloud SQL for MySQL

Cloud SQL for MySQL is a fully managed database service that helps you set up, maintain, manage, and administer your MySQL relational databases on Google Cloud Platform.

Spring Boot

Spring Boot makes it easy to create stand-alone, production-grade Spring-based Applications that you can "just run". 


2. Create a GCP Project

First, Sign into the Google console at https://console.cloud.google.com.

You can create a new project by first selecting the project dropdown in the top left and selecting "New Project".


Next, specify your GCP Project name and Project ID.

Then Click on the "CREATE" button.

Copy "Project ID" and keep it for future purposes.


3. Create a Cloud SQL for MySQL instance.

From cloud console, search for "SQL" like below and click on "SQL" button.


Next, click on "CREATE INSTANCE" button,

Then, click on "Choose MySQL" button,

Then, enable the Compute Engine API by click on "ENABLE API" button.

After that, enter "Instance Id", "Password", "Choose a configuration to start with", "Region" etc...

Note "Password" and keep it safely for future purposes.

Then click on "CREATE INSTANCE" button,


Next, copy "Connection name" and keep it for future purposes.


4. Create a Database.

Click on "CREATE DATABASE" button,

Enter "Database name" and then click on "CREATE" button.

Copy "Database name" and keep it for future purposes.


5. Enable SQL admin API

From cloud console, search for "sqladmin API" like below and click on "sqladmin API" button.

Next, click on "ENABLE" button,


6. Create a service account key

First choose "IAM & Admin" and then click on "Service accounts".

After that, click on "CREATE SERVICE ACCOUNT".

Then, enter service account details like "Service account name", and "Service account ID" and click on "CREATE AND CONTINUE".

Then, grant basic role Editor.

Finally click on "DONE" button.

Then, from "Actions" click on "Manage keys".

Then, click on "Create new key".

Then, choose "Key type" as JSON and click on "CREATE" button.

Service account keys in JSON format will be download. Keep the file safe for future purposes.


7. Creating a simple spring boot web application

First, open the Spring initializr https://start.spring.io/ 

Then, Provide the Group and Artifact name. We have provided Group name com.knf.dev.demo and Artifact spring-boot-gcp-sql-mysql-crud. Here I selected the Maven project - language Java 17 - Spring Boot 3.0.3 and add Spring web dependency and GCP Support.

Then, click on the Generate button. When we click on the Generate button, it starts packing the project in a .zip(spring-boot-gcp-sql-mysql-crud) file and downloads the project. Then, Extract the Zip file. 

Then, import the project on your favourite IDE.

Final Project directory:

Note: Place service account key JSON file in resources folder (Not recommended in production environment).


In the pom.xml, add CloudSQL Starter for MySQL:

<dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>spring-cloud-gcp-starter-sql-mysql</artifactId>
</dependency>


    Complete pom.xml

    <?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>3.0.3</version>
          <relativePath/> <!-- lookup parent from repository -->
       </parent>
       <groupId>com.knf.dev.demo</groupId>
       <artifactId>spring-boot-gcp-sql-mysql-crud</artifactId>
       <version>0.0.1-SNAPSHOT</version>
       <name>spring-boot-gcp-sql-mysql-crud</name>
       <description>Demo project for Spring Boot</description>
       <properties>
          <java.version>17</java.version>
          <spring-cloud-gcp.version>4.1.1</spring-cloud-gcp.version>
          <spring-cloud.version>2022.0.1</spring-cloud.version>
       </properties>
       <dependencies>
          <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
          </dependency>
          <dependency>
             <groupId>com.google.cloud</groupId>
             <artifactId>spring-cloud-gcp-starter</artifactId>
          </dependency>
          <!-- Add CloudSQL Starter for MySQL -->
          <dependency>
             <groupId>com.google.cloud</groupId>
             <artifactId>spring-cloud-gcp-starter-sql-mysql</artifactId>
          </dependency>

          <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
          </dependency>
       </dependencies>
       <dependencyManagement>
          <dependencies>
             <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
             </dependency>
             <dependency>
                <groupId>com.google.cloud</groupId>
                <artifactId>spring-cloud-gcp-dependencies</artifactId>
                <version>${spring-cloud-gcp.version}</version>
                <type>pom</type>
                <scope>import</scope>
             </dependency>
          </dependencies>
       </dependencyManagement>

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

    </project>


    application.properties

    Add the following configuration to application.properties file:
    spring.cloud.gcp.sql.database-name=userdb
    spring.cloud.gcp.sql.instance-connection-name=knf-gcp-demo-project:us-central1:knf-demo-instance
    spring.cloud.gcp.project-id=knf-gcp-demo-project
    spring.cloud.gcp.credentials.location=classpath:knf-gcp-demo-project-c645f5a3af56.json

    spring.sql.init.mode=always
    server.error.include-message=always

    # Leave empty for root, uncomment and fill out if you specified a user
    #spring.datasource.username=

    # Uncomment if root password is specified
    spring.datasource.password=YourPassword

    • Specify database name, instance name, project id, credential's location, and datasource password.
    • The configuration property spring.sql.init.mode=always means that Spring Boot will automatically generate a database schema, using the schema.sql file that we will create later, each time the server is started.

    Note: In this example, we placed service account key JSON file in resources folder (Not recommended in production environment).

    More secure way is place JSON in somewhere in server or docker image, then create environment variable "GOOGLE_APPLICATION_CREDENTIALS" and give the location to your JSON FILE.

    If your application is running on Google App Engine or Google Compute Engine, in most cases you should omit the "spring.cloud.gcp.credentials.location" property and instead, let Spring Cloud GCP Core Starter find the correct credentials for those environments.


    schema.sql

    CREATE TABLE IF NOT EXISTS users(
     id INT PRIMARY KEY AUTO_INCREMENT,
     first_name VARCHAR (20) NOT NULL,
     last_name VARCHAR (20) NOT NULL,
     email VARCHAR (20) NOT NULL
    );


    Create User Model

    package com.knf.dev.demo.model;

    public class User {
        private Long id;
        private String firstName;
        private String lastName;
        private String email;

        public User(Long id, String firstName, String lastName, String email) {
            this.id = id;
            this.firstName = firstName;
            this.lastName = lastName;
            this.email = email;
        }

        public Long getId() {
            return id;
        }

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

        public String getFirstName() {
            return firstName;
        }

        public void setFirstName(String firstName) {
            this.firstName = firstName;
        }

        public String getLastName() {
            return lastName;
        }

        public void setLastName(String lastName) {
            this.lastName = lastName;
        }

        public String getEmail() {
            return email;
        }

        public void setEmail(String email) {
            this.email = email;
        }
    }


    Create User Repository - UserRepository.java

    package com.knf.dev.demo.repository;

    import com.knf.dev.demo.model.User;
    import java.util.List;

    public interface UserRepository {

        public User findById(Long id);

        public List<User> findAll();

        public int insert(User user);

        public int update(User user);

        public int deleteById(Long id);
    }


    Create UserRepositoryImpl.java

    package com.knf.dev.demo.repository;

    import com.knf.dev.demo.exception.ResourceNotFoundException;
    import com.knf.dev.demo.model.User;
    import org.springframework.dao.EmptyResultDataAccessException;
    import org.springframework.jdbc.core.JdbcTemplate;
    import org.springframework.stereotype.Repository;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.List;

    @Repository
    public class UserRepositoryImpl implements UserRepository{

        private final JdbcTemplate jdbcTemplate;

        public UserRepositoryImpl(JdbcTemplate jdbcTemplate) {
            this.jdbcTemplate = jdbcTemplate;
        }

        @Override
        public User findById(Long id) {

            String sqlQuery = Query.FIND_ONE;
            User user = null;
            try {
                 user = jdbcTemplate.
                        queryForObject(sqlQuery,
                                this::mapRowToUser, id);
            }catch(EmptyResultDataAccessException e)
            {
               throw new ResourceNotFoundException
                       ("User not exist with id :" + id);
            }
            return user;
        }

        @Override
        public List<User> findAll() {

            String sqlQuery = Query.FIND_ALL;

            return jdbcTemplate.
                    query(sqlQuery, this::mapRowToUser);
        }

        @Override
        public int insert(User user) {

            String sqlQuery = Query.SAVE;

            return jdbcTemplate.update(sqlQuery,
                    user.getFirstName(),
                    user.getLastName(),
                    user.getEmail());
        }

        @Override
        public int update(User user) {

            String sqlQuery = Query.UPDATE;

            return jdbcTemplate.update(sqlQuery,
                    user.getFirstName(),
                    user.getLastName(),
                    user.getEmail(),
                    user.getId());
        }

        @Override
        public int deleteById(Long id) {

            String sqlQuery = Query.DELETE;

            return jdbcTemplate.update(sqlQuery, id);
        }

        private User mapRowToUser(ResultSet resultSet, int rowNum)
                throws SQLException {

            User user = new User(resultSet.getLong("id"),
                    resultSet.getString("first_name"),
                    resultSet.getString("last_name"),
                    resultSet.getString("email"));

            return user;
        }
    }
    • JdbcTemplate is a powerful mechanism to connect to the database and execute SQL queries. It internally uses JDBC api, but eliminates a lot of problems of JDBC API.
    • The @Repository annotation is a specialization of the @Component annotation which indicates that an annotated class is a "Repository".


    Query.java

    package com.knf.dev.demo.repository;

    public class Query {

        public static final String FIND_ONE = 
                "select id, first_name, last_name,"
                    + " email from users where id = ?";
        
        public static final String FIND_ALL =
                "select id, first_name,last_name,"
                  + " email from users";

        public static final String SAVE =
                "insert into users(first_name, "
                        + "last_name, email) "
                        + "values (?, ?, ?)";

        public static final String UPDATE =
               "update users set " 
                  + "first_name = ?, last_name = ?," 
                       + " email = ? " + "where id = ?";

        public static final String DELETE =
              "delete from users where id = ?";
    }


    ResourceNotFoundException.java

    package com.knf.dev.demo.exception;

    import org.springframework.http.HttpStatus;
    import org.springframework.web.bind.annotation.ResponseStatus;

    @ResponseStatus(value = HttpStatus.NOT_FOUND)
    public class ResourceNotFoundException extends RuntimeException{

        private static final long serialVersionUID = 1L;

        public ResourceNotFoundException(String message) {
            super(message);
        }
    }


    Create User Controller

    package com.knf.dev.demo.controller;

    import com.knf.dev.demo.model.User;
    import com.knf.dev.demo.repository.UserRepository;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.*;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;

    @RestController
    @RequestMapping("/api/v1")
    public class UserController {
        @Autowired
        private UserRepository userRepository;

        // get all users
        @GetMapping("/users")
        public List<User> getAllUsers()
        {
            return userRepository.findAll();
        }

        // create user rest API
        @PostMapping("/users")
        public Map<String, Boolean> createUser(@RequestBody User user)  {

            Map<String, Boolean> response = new HashMap<>();

            Boolean bool = userRepository.insert(user) > 0 ?
                    response.put("created", Boolean.TRUE) :
                    response.put("created", Boolean.FALSE);

            return response;

        }

        // get user by id rest api
        @GetMapping("/users/{id}")
        public User findUserById(@PathVariable Long id) {

            User user = userRepository.findById(id);
            return user;
        }

       // update user rest api
       @PutMapping("/users/{id}")
       public Map<String, Boolean> updateUser(@PathVariable Long id,
                                              @RequestBody User userDetails) {

           userDetails.setId(id);
           Map<String, Boolean> response = new HashMap<>();

           Boolean bool = userRepository.update(userDetails) > 0 ?
                   response.put("updated", Boolean.TRUE) :
                   response.put("updated", Boolean.FALSE);

          return response;
        }

        // delete user rest api
        @DeleteMapping("/users/{id}")
        public Map<String, Boolean> deleteUser
                   (@PathVariable Long id) {

            Map<String, Boolean> response = new HashMap<>();

            Boolean bool = userRepository.deleteById(id) > 0 ?
                    response.put("deleted", Boolean.TRUE) :
                    response.put("deleted", Boolean.FALSE);
            return response;
        }
    }

    • Spring @RestController annotation is used to create RESTful web services using Spring MVC. Spring RestController takes care of mapping request data to the defined request handler method. Once response body is generated from the handler method, it converts it to JSON response.
    • @RequestMapping is used to map web requests onto specific handler classes and/or handler methods. @RequestMapping can be applied to the controller class as well as methods.
    • We can use the @Autowired to mark a dependency which Spring is going to resolve and inject.
    • @GetMapping annotation for mapping HTTP GET requests onto specific handler methods.
    • @PostMapping annotation for mapping HTTP POST requests onto specific handler methods.
    • @PutMapping annotation for mapping HTTP PUT requests onto specific handler methods.
    • @DeleteMapping annotation for mapping HTTP DELETE requests onto specific handler methods.
    • @RequestBody annotation is used to indicating a method parameter should be bind to the body of the HTTP request. Internally, this annotation uses HTTP Message converters to convert the body of HTTP requests to domain objects.
    • @PathVariable annotation used on a method argument to bind it to the value of a URI template variable.


    Run the application - Application.java

    package com.knf.dev.demo;

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

    @SpringBootApplication
    public class Application {

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

    }
    Application is the entry point that sets up the Spring Boot application. The @SpringBootApplication annotation enables auto-configuration and component scanning.

    Step1: Download or clone the source code from GitHub to a local machine - Click here!


    Step 2: mvn clean install


    Step 3: Run the Spring Boot application - mvn spring-boot:run


    OR 


    Run this Spring boot application from 

    • IntelliJ IDEA IDE by right click - Run 'Application.main()' 
    • Eclipse/STS - You can right click the project or the Application.java file and run as java application or Spring boot application.

    Add User:

    Update User:

    Fetch all User:

    Get User by Id:

    Delete User by Id:


    Source code - click here!

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