Is it possible to use both Spring Data R2DBC and Spring Data JPA in a single Spring boot application?

Question

I have an application which is using Spring data JPA and hibernate envers for db auditing. Since R2DBC doesn't support auditing yet, is it possible to use combination of both in a single application?

If yes, Plan is to use Spring Data JPA for insert, update and delete operations, so that all DB auditing will be handled by hibernate envers. And use R2DBC for reactive non-blocking API's to read data.

If no, Is there any suggestions on how to achieve both reactive API's and auditing?

Answer 1

1. Spring provided simple Auditing via @EnableR2dbcAuditing, check my example.

2. Mix JPA in a reactive application is also possible, I have an example to demo run JPA in a reactive application, but not added r2dbc in it.

3. For your plan, a better solution is applying the cqrs pattern on the database topology, use database cluster for your application.

   • JPA for applying changes, use the main/master database to accept the modification, and sync changes to the secondary/slave database.
   • r2dbc for queries as you expected, use the secondary/slave database to query.
   • use a gateway at the front for the query and command service.

Update: I have created a sample to demo JPA and R2dbc coexistence in a single webflux application. But I do not suggest using it in real-world applications. Consider the 3rd solution above if you really need it.

Answer 2

Yes it is possible however you will probably face two issues, one is that multiple repos modules handling needs to be explicited (e.g specify the paths of the respective modules).

Secondly, the JDBC/JPA Spring Boot autoconfiguration will be disabled and you need to import it back. Those issues have been reported in Reactive and Non Reactive repository in a Spring Boot application with H2 database And a solution to them and the thought process can be found in this issue: https://github.com/spring-projects/spring-boot/issues/28025

Answer 3

**Here are the changes I did :
I am trying to catch a trigger from postgres on updation of the table content.** 

**R2dbc Config**

@Configuration
public class R2dbcConfig {

    @Value("${spring.r2dbc.url}")
    private String url;

    @Value("${spring.r2dbc.name}")
    private String name;

    @Value("${spring.r2dbc.username}")
    private String username;

    @Value("${spring.r2dbc.password}")
    private String password;
    @Bean
    public ConnectionFactory connectionFactory() {
        return new PostgresqlConnectionFactory(
                PostgresqlConnectionConfiguration.builder()
                        .host(url)
                        .database(name)
                        .username(username)
                        .password(password)
                        .build()
        );
    }

    @Bean
    DatabaseClient databaseClient(ConnectionFactory connectionFactory) {
        return DatabaseClient.builder()
                .connectionFactory(connectionFactory)
                .namedParameters(true)
                .build();
    }
}

**Jpa Config:**

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = "com.artemis.repositories")
@EntityScan("com.artemis.entities")
@Slf4j
public class JpaConfig implements EnvironmentAware {

    private static final String ENV_HIBERNATE_DIALECT = "hibernate.dialect";
    private static final String ENV_HIBERNATE_HBM2DDL_AUTO = "hibernate.hbm2ddl.auto";
    private static final String ENV_HIBERNATE_SHOW_SQL = "hibernate.show_sql";
    private static final String ENV_HIBERNATE_FORMAT_SQL = "hibernate.format_sql";
    private Environment env;

    @Bean
    public DataSource dataSource() {
        return new DriverManagerDataSource(
                env.getProperty("datasource.url"),
                env.getProperty("datasource.username"),
                env.getProperty("datasource.password")
        );
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource) {
        LocalContainerEntityManagerFactoryBean emf = new LocalContainerEntityManagerFactoryBean();
        emf.setDataSource(dataSource);
        emf.setPackagesToScan(ArtemisApplication.class.getPackage().getName());
        emf.setPersistenceProvider(new HibernatePersistenceProvider());
        emf.setJpaProperties(jpaProperties());
        return emf;
    }

    private Properties jpaProperties() {
        Properties extraProperties = new Properties();
        extraProperties.put(ENV_HIBERNATE_FORMAT_SQL, env.getProperty(ENV_HIBERNATE_FORMAT_SQL));
        extraProperties.put(ENV_HIBERNATE_SHOW_SQL, env.getProperty(ENV_HIBERNATE_SHOW_SQL));
        extraProperties.put(ENV_HIBERNATE_HBM2DDL_AUTO, env.getProperty(ENV_HIBERNATE_HBM2DDL_AUTO));
        if (log.isDebugEnabled()) {
            log.debug(" hibernate.dialect @" + env.getProperty(ENV_HIBERNATE_DIALECT));
        }
        if (env.getProperty(ENV_HIBERNATE_DIALECT) != null) {
            extraProperties.put(ENV_HIBERNATE_DIALECT, env.getProperty(ENV_HIBERNATE_DIALECT));
        }
        return extraProperties;
    }

    @Bean
    public PlatformTransactionManager transactionManager(LocalContainerEntityManagerFactoryBean entityManagerFactory) {
        return new JpaTransactionManager(entityManagerFactory.getObject());
    }

    @Override
    public void setEnvironment(Environment environment) {
        this.env = environment;
    }
}

And my service class:

class myService{

    final PostgresqlConnection connection;

    public myService(ConnectionFactory connectionFactory ) {
        this.connection =  Mono.from(connectionFactory.create())
                .cast(PostgresqlConnection.class).block();
    }

    @PostConstruct
    private void postConstruct() {
        connection.createStatement("LISTEN my_channel").execute()
                .flatMap(PostgresqlResult::getRowsUpdated).subscribe();
        connection.getNotifications().subscribe(myService::catchTrigger);
    }

    private static void catchTrigger(Notification notification) {
        System.out.println(notification.getName());
        System.out.println(notification.getParameter());
    }
}