In this post, we will be creating a reactive rest application using Spring webFlux and spring-data-r2dbc

Dependency required for spring-data-r2dbc

<!-- webflux -->
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

<!-- spring-data-r2dbc-->
<dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-r2dbc</artifactId>
    <version>${spring-data-r2dbc.version}</version>
  </dependency>
  <dependency>
    <groupId>io.r2dbc</groupId>
    <artifactId>r2dbc-postgresql</artifactId>
    <version>${r2dbc.version}</version>
  </dependency>

Setup your environment

1. This example use docker in locally to spin up postgreSQL
2. If you have Docker installed in your system, please run the following command to start PostgreSQL and Adminer (Database management web tool)

  docker-compose -f docker/docker-compose.yml up

1. Verify postgreSQL is up and running

  docker ps -a | grep postgres

output

  48414afd73fc  postgres   "docker-entrypoint.s…"   2 days ago  etc....

1. Verify Adminer (Database management web tool) is up and running

  docker ps -a | grep adminer

output

  3b2402e3d8cb        adminer                                 "entrypoint.sh docke…"   2 days ago

1. You can access Adminer from browser using the following url

     http://localhost:8080/
   

Register ConnectionFactory

@Configuration
@EnableR2dbcRepositories(basePackages = "com.nbenja.spring.r2dbcpostgresqlexample.repository")
public class R2dbcPostgresqlConfiguration extends AbstractR2dbcConfiguration {

  @Value("${datasource.host}")
  private String host;
  @Value("${datasource.port}")
  private int port;
  @Value("${datasource.database}")
  private String database;
  @Value("${datasource.username}")
  private String username;
  @Value("${datasource.password}")
  private String password;
@Bean
@Override
public PostgresqlConnectionFactory connectionFactory() {
  return new PostgresqlConnectionFactory(PostgresqlConnectionConfiguration
      .builder()
      .host(host)
      .database(database)
      .username(username)
      .password(password)
      .port(port)
      .build());
}
}

Once we extend AbstractR2dbcConfiguration and provide the right ConnectionFactory spring-data-r2dbc framework will register DatabaseClient for database interaction for Repository implementation.

Configure your Repository

Currently spring-data-r2dbc provide two interaces to the Repository layer.

1. R2dbcRepository
2. ReactiveCrudRepository

In our example we extend ReactiveCrudRepository

public interface UserRepository extends ReactiveCrudRepository<User, Integer> {

}

Unit test

The unit testcases will be using TestContainers to spin up the lightweight postgresql container instance.

Running the application

Right click and runR2dbcPostgresqlExampleApplication from any IDE or you can run from command line using the following

java -jar target/r2dbc-postgresql-example-0.0.1-SNAPSHOT.jar

Create a new USER

curl -X POST \
  http://localhost:7878/users \
  -H 'Content-Type: application/json' \
  -d '{
	"name": "demo"
}'

get all USERS

curl -X GET http://localhost:7878/users

response:
[{"id":1,"name":"demo"}]%

The code used in this article can be found here .