Since Reactor has taken over the Java world it was inevitable the a reactive sql library would be there.
In this blog we shall use r2dbc with h2 and reactor.
We shall start with the dependencies needed.
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 | <?xml version="1.0" encoding="UTF-8"?> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.5.2</version> </parent> <groupId>com.gkatzioura</groupId> <artifactId>r2dbc-reactor</artifactId> <version>1.0-SNAPSHOT</version> <properties> <maven.compiler.source>11</maven.compiler.source> <maven.compiler.target>11</maven.compiler.target> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-r2dbc</artifactId> </dependency> <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-commons</artifactId> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>io.r2dbc</groupId> <artifactId>r2dbc-h2</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>io.projectreactor</groupId> <artifactId>reactor-test</artifactId> <scope>test</scope> </dependency> </dependencies></project> |
We imported spring data from r2dbc, the h2 r2dbc driver, the h2 binary as well as the test utils.
Supposing that this is our schema.
This schema is a postgresql schema.
1 2 3 4 5 6 | create table order_request ( id uuid NOT NULL constraint or_id_pk primary key, created_by varchar, created timestamp default now() not null, updated timestamp default now() not null); |
We shall add it later to test/resources/schema.sql for testing purposes.
Also let’s add a new model
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 | package com.gkatzioura.r2dbc.model;import java.time.LocalDateTime;import java.util.UUID;import org.springframework.data.annotation.Id;import org.springframework.data.domain.Persistable;import org.springframework.data.relational.core.mapping.Table;@Table("order_request")public class OrderRequest implements Persistable<UUID> { @Id private UUID id; private String createdBy; private LocalDateTime created; private LocalDateTime updated; public void setId(UUID id) { this.id = id; } public String getCreatedBy() { return createdBy; } public void setCreatedBy(String createdBy) { this.createdBy = createdBy; } public LocalDateTime getCreated() { return created; } public void setCreated(LocalDateTime created) { this.created = created; } public LocalDateTime getUpdated() { return updated; } public void setUpdated(LocalDateTime updated) { this.updated = updated; } @Override public UUID getId() { return id; } @Override public boolean isNew() { return created == null; }} |
Pay attention to isNew method. This way the repository can identify if the object should be persisted or updated.
Now onwards to our Repository
1 2 3 4 5 6 7 8 | package com.gkatzioura.r2dbc.repository;import java.util.UUID;import org.springframework.data.repository.reactive.ReactiveCrudRepository;import com.gkatzioura.r2dbc.model.OrderRequest;public interface OrderRepository extends ReactiveCrudRepository<OrderRequest, UUID> {} |
Let’s put some tests.
As mentioned the schema above will reside in test/resources/schema.sql
We shall add some configuration for the test h2 db. We need to make sure that h2 will pickup the postgresql interface.
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 | package com.gkatzioura.r2dbc;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.core.io.ClassPathResource;import org.springframework.data.r2dbc.config.AbstractR2dbcConfiguration;import org.springframework.data.r2dbc.repository.config.EnableR2dbcRepositories;import org.springframework.r2dbc.connection.init.CompositeDatabasePopulator;import org.springframework.r2dbc.connection.init.ConnectionFactoryInitializer;import org.springframework.r2dbc.connection.init.ResourceDatabasePopulator;import io.r2dbc.h2.H2ConnectionFactory;import io.r2dbc.spi.ConnectionFactory;@Configuration@EnableR2dbcRepositoriespublic class H2ConnectionConfiguration extends AbstractR2dbcConfiguration { @Override public ConnectionFactory connectionFactory() { return new H2ConnectionFactory( io.r2dbc.h2.H2ConnectionConfiguration.builder() .url("mem:testdb;MODE=PostgreSQL;DB_CLOSE_DELAY=-1;") .build() ); } @Bean public ConnectionFactoryInitializer initializer() { var initializer = new ConnectionFactoryInitializer(); initializer.setConnectionFactory(connectionFactory()); var databasePopulator = new CompositeDatabasePopulator(); databasePopulator.addPopulators(new ResourceDatabasePopulator(new ClassPathResource("schema.sql"))); initializer.setDatabasePopulator(databasePopulator); return initializer; }} |
With this configuration we create a H2 database simulating a Postgresql DB, we create the schemas as well as enable the creation of the R2DBC repositories.
Also let’s add a test.
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | package com.gkatzioura.r2dbc.repository;import java.util.UUID;import org.junit.jupiter.api.Test;import org.junit.jupiter.api.extension.ExtendWith;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Import;import org.springframework.test.context.junit.jupiter.SpringExtension;import com.gkatzioura.r2dbc.H2ConnectionConfiguration;import com.gkatzioura.r2dbc.model.OrderRequest;import reactor.test.StepVerifier;@ExtendWith({SpringExtension.class})@Import({H2ConnectionConfiguration.class})class OrderRepositoryTest { @Autowired private OrderRepository orderRepository; @Test void testSave() { UUID id = UUID.randomUUID(); OrderRequest orderRequest = new OrderRequest(); orderRequest.setId(id); orderRequest.setCreatedBy("test-user"); var persisted = orderRepository.save(orderRequest) .map(a -> orderRepository.findById(a.getId())) .flatMap(a -> a.map(b -> b.getId())); StepVerifier.create(persisted).expectNext(id).verifyComplete(); }} |
That’s it, you can find the code on github.
Published on Java Code Geeks with permission by Emmanouil Gkatziouras, partner at our JCG program. See the original article here: Using R2DBC with a Reactor Application Opinions expressed by Java Code Geeks contributors are their own. |
