R2DBC Code Example (Spring Data)

Overview

The following example uses the Spring Data R2DBC framework to select data from the table defined in Setup for Example. Complete information on using Connector/R2DBC with the Spring Data framework is available.

//Module Imports
import org.mariadb.r2dbc.MariadbConnectionConfiguration;
import org.mariadb.r2dbc.MariadbConnectionFactory;
import org.springframework.data.r2dbc.core.DatabaseClient;
import reactor.test.StepVerifier;

// Main Application Class
public class App {
  // Connection Configuration
  private static MariadbConnectionConfiguration conf;
  private static MariadbConnectionFactory connFactory;

  private static DatabaseClient client;

  // Main Process
  public static void main(String[] args) {
     try {
        conf = MariadbConnectionConfiguration.builder()
             !SILO=ent!
             .host("192.0.2.1").port(3306)
             !SILO=sky!
             .host("example.skysql.net").port(5509)
             !END-SILO!
             .username("db_user").password("db_user_password")
             .database("test").build();

        // Instantiate a Connection Factory
        connFactory = new MariadbConnectionFactory(conf);

        // Instantiate a Database Client
        client = DatabaseClient.create(connFactory);

        // Select all rows
        client.select()
           .from(Contact.class)
           .fetch().all()
           .doOnNext(it -> System.out.println(it))
           .as(StepVerifier::create)
           .expectNextCount(3)
           .verifyComplete();

        // Select the first row
        client.select()
           .from(Contact.class)
           .fetch().first()
           .doOnNext(it -> System.out.println(it))
           .as(StepVerifier::create)
           .expectNextCount(1)
           .verifyComplete();

        // Select all rows with explicit query
        client.execute("SELECT id, first_name,last_name,email FROM contact")
           .as(Contact.class)
           .filter(s -> s.fetchSize(25))
           .fetch().all()
           .doOnNext(it -> System.out.println(it))
           .as(StepVerifier::create)
           .expectNextCount(3)
           .verifyComplete();

        // Select single column
        client.execute("SELECT first_name FROM contact")
           .map((row, rowMetadata) -> row.get("first_name", String.class))
           .all()
           .doOnNext(it -> System.out.println(it))
           .as(StepVerifier::create)
           .expectNextCount(3)
           .verifyComplete();

     } catch (IllegalArgumentException e) {
        e.printStackTrace();
     } catch (io.r2dbc.spi.R2dbcNonTransientResourceException e) {
        e.printStackTrace();
     } finally {
     }
  }
}

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