Spring Data R2DBC

Spring Data introduced reactive programming support with the release of Spring Data Reactive Modules. This module allows you to work with reactive database drivers (like MongoDB Reactive, R2DBC for SQL databases, etc.) and provides APIs for performing asynchronous database operations using reactive streams.

Spring Data R2DBC is an addition, to the Spring Data project that offers a programming model for databases with a focus on programming. Unlike implementations, like JDBC (Java Database Connectivity) or JPA (Java Persistence API) Spring Data R2DBC adopts a blocking approach enabling developers to handle database operations in a reactive manner.

Why use Spring Data R2DBC?

• Building high-performance applications: A high-performance e-commerce application could use Spring Data R2DBC to handle the large number of requests that it receives.
• Building scalable applications: A scalable social media application could use Spring Data R2DBC to handle the large number of users and posts that it needs to manage.
• Building microservices: A microservices architecture could use Spring Data R2DBC to connect the different microservices and allow them to communicate with each other using a reactive API.
• Building event-driven applications: An event-driven application could use Spring Data R2DBC to react to events that occur in the database, such as a new customer being created or an order being placed.
• Building reactive applications: A reactive real-time chat application could use Spring Data R2DBC to keep track of the latest messages and send them to users in real-time.

Requirements to setup Spring Data R2DBC Application

• Java 17 or higher
• Spring Framework 6.0.11 or higher
• R2DBC and above
• A database that supports R2DBC, such as PostgreSQL, MySQL, or MongoDB

Dependencies

Maven Dependencies:

<dependencies>
   <!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-r2dbc -->
    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-r2dbc</artifactId>
        <version>3.1.3</version>
    </dependency>

   <!-- R2DBC driver for your chosen database -->
   <!-- https://mvnrepository.com/artifact/io.r2dbc/r2dbc-postgresql -->
    <dependency>
        <groupId>io.r2dbc</groupId>
        <artifactId>r2dbc-postgresql</artifactId>
        <version>0.8.13.RELEASE</version>
    </dependency>

    <!-- Spring Boot Starter for Web (Optional, if building a web application) -->
    <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-web -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <version>3.1.3</version>
    </dependency>
  
    <!-- Other dependencies your application may need -->
  
</dependencies>

Gradle Dependencies:

dependencies {
    // Spring Boot Starter for R2DBC
    implementation 'org.springframework.boot:spring-boot-starter-data-r2dbc'

    // R2DBC driver for your chosen database
    implementation 'io.r2dbc:r2dbc-postgresql' // Example for PostgreSQL

    // Spring Boot Starter for Web (Optional, if building a web application)
    implementation 'org.springframework.boot:spring-boot-starter-web'

    // Other dependencies your application may need
}

Basic steps to connect a database to a Spring Data R2DBC Application

1. Add R2DBC driver dependency in pom.xml. For example for Postgres:

<dependency>
  <groupId>io.r2dbc</groupId>
  <artifactId>r2dbc-postgresql</artifactId>
</dependency>

2. Define database configuration properties in application.properties:

spring.r2dbc.url=r2dbc:postgresql://localhost:5432/database
spring.r2dbc.username=username
spring.r2dbc.password=password

3. Autowire ConnectionFactory in a configuration class:

@Configuration
public class R2dbcConfig {

  @Autowired
  ConnectionFactory connectionFactory;

}

4. Define entity classes and repository interfaces:

5. Autowire repository in a service class:

@Service
public class UserService {

  private UserRepository userRepository;

  public UserService(UserRepository userRepository) {
    this.userRepository = userRepository;
  }

}

6. Run the application. Spring Data R2DBC will autoconfigure the connection:

7. Invoke repository methods from service classes to perform CRUD operations:

Conclusion

• Spring Data R2DBC is a powerful tool that can be used to access relational databases in a reactive way. It is easy to use and can be used to build scalable and high-performance applications.
• If you are looking for a way to access relational databases in a reactive way, then Spring Data R2DBC is a good option to consider.