Google Cloud SQL for PostgreSQL + Spring Data JPA + Spring Boot - Build REST CRUD APIs

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


1.  A little bit of Background

Spring Data JPA

Spring Data JPA aims to significantly improve the implementation of data access layers by reducing the effort to the amount that’s actually needed. As a developer you write your repository interfaces, including custom finder methods, and Spring will provide the implementation automatically.


Google Cloud SQL for PostgreSQL

Cloud SQL for PostgreSQL is a fully managed database service that helps you set up, maintain, manage, and administer your PostgreSQL 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 PostgreSQL instance.

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


Next, click on "CREATE INSTANCE" button,

Then, click on "Choose PostgreSQL" 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-data-jpa-gcp-sql-postgresql-crud. Here I selected the Maven project - language Java 17 - Spring Boot 3.0.4 and add Spring web dependency, Spring Data JPA, 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-data-jpa-gcp-sql-postgresql-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 PostgreSQL:

<!-- Add CloudSQL Starter for PostgreSQL -->
<dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>spring-cloud-gcp-starter-sql-postgresql</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>3.0.4</version>
          <relativePath/> <!-- lookup parent from repository -->
       </parent>
       <groupId>com.knf.dev.demo</groupId>
       <artifactId>spring-boot-data-jpa-gcp-sql-postgresql-crud</artifactId>
       <version>0.0.1-SNAPSHOT</version>
       <name>spring-boot-data-jpa-gcp-sql-postgresql-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-data-jpa</artifactId>
          </dependency>
          <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 PostgreSQL -->
          <dependency>
             <groupId>com.google.cloud</groupId>
             <artifactId>spring-cloud-gcp-starter-sql-postgresql</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=studentdb
    spring.cloud.gcp.sql.instance-connection-name=knf-gcp-demo-project-123:us-central1:knf-demo-instance
    spring.cloud.gcp.project-id=knf-gcp-demo-project-123
    spring.cloud.gcp.credentials.location=classpath:knf-gcp-demo-project-123-1862d50bc2fd.json

    # 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

    spring.jpa.hibernate.ddl-auto=update
    • Specify database name, instance name, project id, credential's location, and datasource password.
    • spring.jpa.hibernate.ddl-auto is used for database initialization. We set the value to update value so that a table will be created in the database automatically corresponding to defined data model. Any change to the model will also trigger an update to the table.

    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.


    Create Student Entity - Student.java

    package com.knf.dev.demo.entity;

    import jakarta.persistence.*;

    @Entity
    @Table(name = "students")
    public class Student {

        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private Long id;

        @Column(name = "first_name")
        private String firstName;

        @Column(name = "last_name")
        private String lastName;

        private String email;

        public Student() {

        }

        public Student(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;
        }
    }
    • The @Entity annotation specifies that the class is an entity and is mapped to a database table. 
    • The @Table annotation allows you to specify the details of the table that will be used to persist the entity in the database.
    • The @Id annotation specifies the primary key of an entity and the @GeneratedValue provides for the specification of generation strategies for the values of primary keys. 
    • The @Column annotation is used to specify the mapped column for a persistent property or field. If no Column annotation is specified, the default value will be applied.


    Create Student Repository - StudentRepository.java

    package com.knf.dev.demo.repository;

    import com.knf.dev.demo.entity.Student;
    import org.springframework.data.jpa.repository.JpaRepository;

    public interface StudentRepository extends JpaRepository<Student, Long> {

    }

    JpaRepository is JPA specific extension of Repository. It contains the full API of CrudRepository and PagingAndSortingRepository. So, it contains API for basic CRUD operations and also API for pagination and sorting.


    -Exception Handling

    Create custom Exception -ResourceNotFoundException.java

    package com.knf.dev.demo.exception;

    public class ResourceNotFoundException extends RuntimeException{

       private static final long serialVersionUID = 1L;
       
       public ResourceNotFoundException(String message) {
          super(message);
       }
    }


    Create Custom Error Response

    package com.knf.dev.demo.exception;

    import com.fasterxml.jackson.annotation.JsonFormat;
    import java.time.LocalDateTime;

    public class CustomErrorResponse {

        @JsonFormat(shape = JsonFormat.Shape.STRING,
                pattern = "yyyy-MM-dd hh:mm:ss")
        private LocalDateTime timestamp;
        private int status;
        private String error;
        public LocalDateTime getTimestamp() {
            return timestamp;
        }
        public void setTimestamp(LocalDateTime timestamp) {
            this.timestamp = timestamp;
        }
        public int getStatus() {
            return status;
        }
        public void setStatus(int status) {
            this.status = status;
        }
        public String getError() {
            return error;
        }
        public void setError(String error) {
            this.error = error;
        }
    }


    Create Global Exception Handler

    package com.knf.dev.demo.exception;

    import org.springframework.http.HttpStatus;
    import org.springframework.http.ResponseEntity;
    import org.springframework.web.bind.annotation.ControllerAdvice;
    import org.springframework.web.bind.annotation.ExceptionHandler;
    import org.springframework.web.context.request.WebRequest;
    import java.time.LocalDateTime;

    @ControllerAdvice
    public class GlobalExceptionHandler {

        @ExceptionHandler(ResourceNotFoundException.class)
        public ResponseEntity<CustomErrorResponse> globalExceptionHandler
                       (Exception ex, WebRequest request) {
            CustomErrorResponse errors = new CustomErrorResponse();
            errors.setTimestamp(LocalDateTime.now());
            errors.setError(ex.getMessage());
            errors.setStatus(HttpStatus.NOT_FOUND.value());
            return new ResponseEntity<>(errors, HttpStatus.NOT_FOUND);
        }
    }

    Spring supports exception handling by a Global Exception Handler (@ExceptionHandler) with Controller Advice (@ControllerAdvice). This enables a mechanism that makes ResponseEntity work with the type safety and flexibility of @ExceptionHandler.


    Create Student Controller

    package com.knf.dev.demo.controller;

    import com.knf.dev.demo.entity.Student;
    import com.knf.dev.demo.exception.ResourceNotFoundException;
    import com.knf.dev.demo.repository.StudentRepository;
    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 StudentController {

        @Autowired
        private StudentRepository studentRepository;

        // get all students
        @GetMapping("/students")
        public List<Student> getAllStudents()
        {
            return studentRepository.findAll();
        }

        // create student rest API
        @PostMapping("/students")
        public Student createStudent(@RequestBody Student student)  {

            return studentRepository.save(student);

        }

        // get student by id rest api
        @GetMapping("/students/{id}")
        public Student findStudentById(@PathVariable Long id) {

            Student student = studentRepository.findById(id).
                    orElseThrow(() -> new ResourceNotFoundException
                      ("Student not exist with id :" + id));
            return student;
        }

       // update student rest api
       @PutMapping("/students/{id}")
       public Student updateStudent(@PathVariable Long id,
                               @RequestBody Student studentDetails) {

           Student student = studentRepository.findById(id).
                   orElseThrow(() -> new ResourceNotFoundException
                           ("Student not exist with id :" + id));

           student.setFirstName(studentDetails.getFirstName());
           student.setLastName(studentDetails.getLastName());
           student.setEmail(studentDetails.getEmail());

           return studentRepository.save(student);
        }

        // delete student rest api
        @DeleteMapping("/students/{id}")
        public Map<String, Boolean> deleteStudent
                   (@PathVariable Long id) {

            Student student = studentRepository.findById(id).
                    orElseThrow(() -> new ResourceNotFoundException
                            ("Student not exist with id :" + id));


            studentRepository.delete(student);

            Map<String, Boolean> response = new HashMap<>();
            response.put("deleted", Boolean.TRUE);
            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 Student:


    Update Student:


    Fetch all Student:


    Get Student by Id:


    Delete Student:

    Source code - click here!

    Popular posts from this blog

    Learn Java 8 streams with an example - print odd/even numbers from Array and List

    Example 1: Java 8 program to print odd numbers from a List   import java.util.Arrays; import java.util.List; import java.util.stream.Collectors; /*Java 8 Program to find Odd Numbers from a List*/ public class DriverClass { public static void main( String [] args) { List < Integer > numbers = Arrays. asList( 1 , 4 , 8 , 40 , 11 , 22 , 33 , 99 ); List < Integer > oddNumbers = numbers.stream(). filter(o -> o % 2 != 0 ). collect(Collectors.toList()); System.out.println(oddNumbers); } } 1. Initialize List using Arrays.asList() method. Java's built-in Arrays.asList() method converts an array into a list. This method takes an array as an argument and returns a List object. 2.  Java List interface provides stream() method which returns a sequential Stream with list of Integer as its source. 3. The Java stream filter() method allow
    Read more

    Java Stream API - How to convert List of objects to another List of objects using Java streams?

    Image
    In this section, we will show you how to convert a List of objects to another List of objects in Java using the Java streams map(). The ‘map’ method maps each element to its corresponding result. Java Stream API   The Java Stream API provides a functional programming approach over the object oriented capabilities of Java. It is used for processing collections of objects. The Stream in Java can be defined as a sequence of elements from a source List, Set or Array. Most of the stream operations return a Stream. This avails engender a chain of stream operations(stream pipe-lining). The streams withal support the aggregate or terminal operations on the elements. for example, finding the sum or maximum element or finding the average etc...Stream operations can either be executed sequentially or parallel. when performed parallelly, it is called a parallel stream.   Stream map() Method   The Java 8 Stream map() is an intermediate operation. It converts Stream<obj1> to Stream<obj2>
    Read more

    Registration and Login with Spring Boot + Spring Security + Thymeleaf

    Image
    In this section, we will learn how to create user registration and login using Spring boot, Spring security, Thymeleaf, JPA, and H2DB. The GitHub repository link is provided at the end of this tutorial. You can download the source code. Technologies used: Spring Boot 2.5.5  Spring Data JPA  Spring Security  Thymeleaf  Maven 3+  Java 17  H2 Database   User Interface User Registration Authentication Failed Authentication success Sign out Final Project Structure: 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-pare
    Read more

    Java, Spring Boot Mini Project - Library Management System - Download

    Image
    Hello everyone, Hope you are doing well. Here, we provide a Library Management System mini-project for beginners, it's free for download. Maybe you can build more on top of this project and create your own product, that's all about you. The source code download link is provided at the end of this post. 1. Benefit of this project You could cover the following technologies and features by learning and debugging this mini project. Java 17 Java Stream Java Lamda Expressions Java Records Functional programming Object-oriented programming var Keyword in Java Generics in Java Java Switch Spring boot 2.6.4 Spring Security Thymeleaf template engine OpenCSV Spring Data JPA Server Side Pagination H2 Database  Bootstrap HTML CSS and more... 2. Objective Of Spring Boot On Library Management System The main objective of this project is to manage the details of the books, author, category, and publisher. Only Admin/Librarian will manage all these activities. Also, they can export the data in
    Read more

    ReactJS, Spring Boot JWT Authentication Example

    Image
    In this tutorial, we’ll create a user registration & login example using ReactJS, Spring Boot, Spring Security, and JWT authentication. You could download the source code from our Github repository, the download link is provided at the end of this tutorial. Technologies used Backend Technologies: Java 17 Spring Boot 2.7.0 Spring Security Spring Data JPA JWT H2 Database Frontend Technologies: React 17.0.1 Axios 0.27.2 Redux 4.0.5 Bootstrap 4.5.2 ReactJS - SpringBoot - JWT - Flow Backend Project Directory: Frontend Project Directory: Following is the screenshot of our application - User Registration: User Signin: Profile View: Access Resource: We will build two projects:  1. Backend:   spring-boot-security-jwt 2. Frontend: react-redux-jwt Project 1: spring-boot-security-jwt 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"
    Read more

    Top 5 Java ORM tools - 2024

    Image
      The term ORM refers to object-relational mapping, which uses objects to adapt programming languages to database systems while allowing them to function with SQL and object-oriented programming ideas. Any kind of database management system that can accomplish object mapping to the table in the virtual system is suitable for the implementation of ORM. Java has a wide variety of ORM tools, some of which are mentioned below: 1. Hibernate Hibernate is a lightweight, open-source, non-invasive Java ORM (Object-Relational Mapping) framework that allows developers to create objects that function independently of database software and create persistence logic in any Java or JavaEE application. It offers an abstraction layer, so developers don't have to bother about implementations; Hibernate handles these tasks internally, such as connecting to databases and creating queries to carry out CRUD operations, among other things. Persistence logic development is done with it. Persistence logic r
    Read more

    Java - Blowfish Encryption and decryption Example

    Image
    Blowfish is an encryption method developed by Bruce Schneier in 1993 as an alternative to the DES encryption method. It is significantly faster than DES and provides good encryption speed, although no effective cryptanalysis technique has been found to date. It is one of the first secure block ciphers that is not protected by any patents and is therefore freely available for anyone to use. This is a symmetric block cipher algorithm. Block size: 64 bits Key size: variable size from 32 to 448 bits number of subsections: 18 [P-array] number of rounds: 16 number of substitution blocks: 4 [each with 512 records of 32 bits each] develop  Example 1: Encryption and decryption using Blowfish import java.io.UnsupportedEncodingException; import java.nio.charset.Charset; import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import java.util.Base64; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeExc
    Read more

    Spring boot video streaming example-HTML5

    Image
    Hello everyone, Today we will learn how to stream MP4 video using Spring Boot and Spring Web Flux.  The Source code download link is provided at the end of this post. New, Quarkus Practice User Interface   Project Structure: G radle(build.gradle) plugins { id 'org.springframework.boot' version '2.5.4' id 'io.spring.dependency-management' version '1.0.11.RELEASE' id 'java' } group = 'com.knf.demo' version = '0.0.1-SNAPSHOT' sourceCompatibility = '11' repositories { mavenCentral() } dependencies { implementation 'org.springframework.boot:spring-boot-starter-webflux' testImplementation 'org.springframework.boot:spring-boot-starter-test' testImplementation 'io.projectreactor:reactor-test' } test { useJUnitPlatform() } Service (VideoStreamingService.java) package  com.knf.demo.service ; import org.springframework.beans.factory.annotation. Autowired ; import org.springframework
    Read more

    Google Cloud Storage + Spring Boot - File Upload, Download, and Delete

    Image
    In this section, we will learn  how to  create a simple spring boot application to perform different file operations such as upload, download, list, and delete files from the Google Cloud Storage. 1.  A little bit of Background Google Cloud Storage Cloud Storage is a managed service for storing unstructured data. Store any amount of data and retrieve it as often as you like. More Info - click here! Spring Boot Spring Boot makes it easy to create stand-alone, production-grade Spring-based Applications that you can "just run".  More Info - click here! 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 Google Cloud Storage bucket Fr
    Read more