Spring Data R2DBC

Spring Data R2DBC is a Spring Data module that enables reactive, non-blocking database access for relational databases using Mono and Flux. Unlike JDBC or JPA, it avoids blocking calls, making applications more scalable and high-performing.

• Reactive Model: Uses non-blocking APIs with Mono and Flux
• High Performance: Efficiently handles large concurrent requests
• Scalable: Well-suited for microservices and cloud-native systems
• Event-Driven: Ideal for real-time and asynchronous workflows
• Database Support: Works with R2DBC-supported databases like PostgreSQL and MySQL

Prerequisites

• 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:

Gradle Dependencies:

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

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

2. Define database configuration properties in application.properties:

3. Autowire ConnectionFactory in a configuration class:

4. Define entity classes and repository interfaces:

5. Autowire repository in a service class:

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

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

Step-by-Step Implementation

Step 1: Create Spring Boot Project

• Use Spring Initializr
• Select dependencies: Spring Web , Spring Data R2DBC and PostgreSQL Driver (or your DB)
• R2DBC = Reactive (Non-blocking DB access)

Step 2: Add Dependencies

• Add R2DBC + database driver
• Example: PostgreSQL

Maven

Gradle

Step 3: Configure Database

• Configure DB connection in application.properties
• Use R2DBC URL (not JDBC)

spring.r2dbc.url=r2dbc:postgresql://localhost:5432/testdb
spring.r2dbc.username=postgres
spring.r2dbc.password=admin

Step 4: Create Entity Class

• Represents table in database
• Use R2DBC annotations

Employee.java

Step 5: Create Repository Interface

• Extends ReactiveCrudRepository
• Provides CRUD methods automatically

Step 6: Create Service Class

• Contains business logic
• Uses repository methods

Step 7: Create Controller

• Exposes REST APIs
• Calls service methods

Step 8: Run Application

• Spring Boot auto-configures R2DBC
• No manual connection handling required
• Application starts on default port (8080)