Spring Data R2dbc
This post focused on Spring Boot 2.3 or previous version which shipped with Spring Data R2dbc 1.1.
Spring Data R2dbc 1.2 brought plenty of changes and broken APIs. For the newest Spring Boot 2.4 and Spring Data R2dbc 1.2, please go to Spring R2dbc Sample and update yourself to the latest R2dbc.
Getting Started
Generate a Spring Boot project using Spring Initializr, and select the following options.
- Project type: Maven
- Java version : 11
- Spring Boot : 2.2.4.RELEASE
- Dependencies: Reactive Web, Lombok, R2dbc
Open the pom.xml file in the project root folder.
There is a spring-boot-bom-r2dbc
to manage the r2dbc related dependencies.
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot.experimental</groupId>
<artifactId>spring-boot-bom-r2dbc</artifactId>
<version>0.1.0.M3</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
A Spring Boot starter spring-boot-starter-data-r2dbc
dependency is added in the dependencies
.
<dependency>
<groupId>org.springframework.boot.experimental</groupId>
<artifactId>spring-boot-starter-data-r2dbc</artifactId>
</dependency>
Let's add a r2dbc driver for the specific database you are using.
Use H2 as an example, add the following dependency. Other drivers can found in R2dbc website .
<dependency>
<groupId>io.r2dbc</groupId>
<artifactId>r2dbc-h2</artifactId>
<scope>runtime</scope>
</dependency>
In a Spring Boot based project, the spring-boot-starter-data-r2dbc
starter will auto-configure all necessary facilities to get the r2dbc work.
In a none Spring Boot project, you can configure R2dbc manually by declaring a custom AbstractR2dbcConfiguration
.
@Configuration
@EnableR2dbcRepositories
public class DatabaseConfig extends AbstractR2dbcConfiguration {
@Override
@Bean
public ConnectionFactory connectionFactory() {
//ConnectionFactory factory = ConnectionFactories.get("r2dbc:h2:mem:///test?options=DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE");
//see: https://github.com/spring-projects/spring-data-r2dbc/issues/269
// return new H2ConnectionFactory(
// H2ConnectionConfiguration.builder()
// //.inMemory("testdb")
// .file("./testdb")
// .username("user")
// .password("password").build()
// );
return H2ConnectionFactory.inMemory("testdb");
}
@Bean
ReactiveTransactionManager transactionManager(ConnectionFactory connectionFactory) {
return new R2dbcTransactionManager(connectionFactory);
}
}
In the above codes:
-
ConnectionFactory
is required to connect to a database. - and
ReactiveTransactionManager
is use for reactive transaction management. -
@EnableR2dbcRepositories
will recognizeRepository
interface. - In the background, it also configured a
DatabaseClient
which allow you to execute criteria like query on database.
In a Spring Boot project, all these are configured for you, if you want to adjust some properties, for example, to use PostgresSQL instead of H2, firstly declare a r2dbc-postgresql
dependency instead.
<dependency>
<groupId>io.r2dbc</groupId>
<artifactId>r2dbc-postgresql</artifactId>
</dependency>
Secondly, add r2dbc connection info for your PostgresSQL in application.properties.
spring.r2dbc.url=r2dbc:postgresql://localhost/test
spring.r2dbc.username=user
spring.r2dbc.password=password
spring.r2dbc.initialization-mode=always
Let's go ahead.
Create a POJO to present data in the database table.
@Data
@ToString
@Builder
@NoArgsConstructor
@AllArgsConstructor
@Table("posts")
class Post {
@Id
@Column("id")
private Integer id;
@Column("title")
private String title;
@Column("content")
private String content;
}
The @Table
and @Column
annotations define the mapping rule between the POJO and the backing table and its columns, @Id
indicates id
is the table primary key.
Create a Repository
interface for the Post
entity.
interface PostRepository extends ReactiveCrudRepository<Post, Integer> {
@Query("SELECT * FROM posts WHERE title like $1")
Flux<Post> findByTitleContains(String name);
}
As you see, similar to the Repository
working in other Spring Data projects, it also supports custom @Query
on method. But there is a limitation in the current 1.0.0 version of Spring Data R2dbc , the query derivation is not support, if you want to customize the query, the @Query
is a must.
Next, let's create a @RestController
to expose simple CRUD endpoints for Post.
@RestController()
@RequestMapping(value = "/posts")
@RequiredArgsConstructor
class PostController {
private final PostRepository posts;
@GetMapping("")
public Flux<Post> all() {
return this.posts.findAll();
}
@PostMapping("")
public Mono<Post> create(@RequestBody Post post) {
return this.posts.save(post);
}
@GetMapping("/{id}")
public Mono<Post> get(@PathVariable("id") Integer id) {
return this.posts.findById(id);
}
@PutMapping("/{id}")
public Mono<Post> update(@PathVariable("id") Integer id, @RequestBody Post post) {
return this.posts.findById(id)
.map(p -> {
p.setTitle(post.getTitle());
p.setContent(post.getContent());
return p;
})
.flatMap(p -> this.posts.save(p));
}
@DeleteMapping("/{id}")
public Mono<Void> delete(@PathVariable("id") Integer id) {
return this.posts.deleteById(id);
}
}
Unlike JPA, Spring Data R2dbc does not maintain the database schemas, so you have to do it yourself. Spring Data R2dbc provides a ConnectionFactoryInitializer
to allow you execute sql scripts on database when it is connected. In a Spring Boot application, it is configured for you automatically. When the application is starting up, it will scan schema.sql
and data.sql
files in the classpath to initialize the database.
Here is a schema.sql
file to create tables.
CREATE TABLE IF NOT EXISTS posts (id SERIAL PRIMARY KEY, title VARCHAR(255), content VARCHAR(255));
The following script is to load sample data.
DELETE FROM posts;
INSERT INTO posts (title, content) VALUES ('post one', 'content of post one');
You can also customize a ConnectionFactoryInitializer
bean to execute the your scripts.
@Bean
public ConnectionFactoryInitializer initializer(ConnectionFactory connectionFactory) {
ConnectionFactoryInitializer initializer = new ConnectionFactoryInitializer();
initializer.setConnectionFactory(connectionFactory);
CompositeDatabasePopulator populator = new CompositeDatabasePopulator();
populator.addPopulators(new ResourceDatabasePopulator(new ClassPathResource("schema.sql")));
populator.addPopulators(new ResourceDatabasePopulator(new ClassPathResource("data.sql")));
initializer.setDatabasePopulator(populator);
return initializer;
}
Additionally, if you are using Docker to serve a database, it also leaves room for you to initialize database when database is started, use volumes to map your local folder which includes a init.sql
to the path /docker-entrypoint-initdb.d
in Docker container.
An example for MySQL.
mysql:
image: mysql:5.7
ports:
- "3306:3306"
# command: --default-authentication-plugin=mysql_native_password
environment:
MYSQL_ROOT_PASSWORD: mysecret
MYSQL_USER: user
MYSQL_PASSWORD: password
MYSQL_DATABASE: test
volumes:
# - ./data/mysql:/var/lib/mysql
- ./mysql-initdb.d:/docker-entrypoint-initdb.d
And the following is the content of mysql-initdb.d/init.sql.
use test;
CREATE TABLE IF NOT EXISTS posts(
id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
title VARCHAR(255) NOT NULL,
content VARCHAR(255) NOT NULL
);
If the tables are existed, you can use a CommandLineRunner
or ApplicationRunner
to initialize the sample instead of the data.sql
script.
@Component
@Slf4j
@RequiredArgsConstructor
class DataInitializer implements ApplicationRunner {
private final PostRepository posts;
@Override
public void run(ApplicationArguments args) throws Exception {
log.info("start data initialization...");
this.posts
.saveAll(
List.of(
Post.builder().title("Post one").content("The content of post one").build(),
Post.builder().title("Post tow").content("The content of post tow").build()
)
)
.thenMany(
this.posts.findAll()
)
.subscribe((data) -> log.info("post:" + data),
(err) -> log.error("error" + err),
() -> log.info("initialization is done...")
);
}
}
Now start up your application, and use curl
to test /posts
endpoints.
#curl http://localhost:8080/posts
[{"id":1,"title":"post one","content":"content of post one"},{"id":2,"title":"Post one","content":"The content of post one"},{"id":3,"title":"Post tow","content":"The content of post tow"}]
Awesome! it works well.
OK, let's move forward.
Testing
Spring Data R2dbc also provide a @DataR2dbcTest
for test slice purpose which is use for testing your R2dbc related facilities without load all configurations.
@DataR2dbcTest
public class PostRepositoryTest {
@Autowired
DatabaseClient client;
@Autowired
PostRepository posts;
@Test
public void testDatabaseClientExisted() {
assertNotNull(client);
}
@Test
public void testPostRepositoryExisted() {
assertNotNull(posts);
}
@Test
public void testInsertAndQuery() {
this.client.insert()
.into("posts")
//.nullValue("id", Integer.class)
.value("title", "testtitle")
.value("content", "testcontent")
.then().block(Duration.ofSeconds(5));
this.posts.findByTitleContains("testtitle")
.take(1)
.as(StepVerifier::create)
.consumeNextWith(p -> assertEquals("testtitle", p.getTitle()))
.verifyComplete();
}
}
But unfortunately, it does not work as @DataJpaTest
which can pick up an embedded H2 for test purpose, with @DataR2dbcTest
, we have to use a runtime database, see #issue62.
DatabaseClient
As mentioned, a DatabaseClient
is available for database operations in a programmatic approach instead of Repository
interface declaring.
Here is an example of PostRepository
using DatabaseClient
.
@RequiredArgsConstructor
@Component
public class PostRepository {
private final DatabaseClient databaseClient;
Flux<Post> findByTitleContains(String name) {
return this.databaseClient.select()
.from(Post.class)
.matching(where("title").like(name))
.fetch()
.all();
}
public Flux<Post> findAll() {
return this.databaseClient.select()
.from(Post.class)
.fetch()
.all();
}
public Mono<Post> findById(Integer id) {
return this.databaseClient.select()
.from(Post.class)
.matching(where("id").is(id))
.fetch()
.one();
}
public Mono<Integer> save(Post p) {
return this.databaseClient.insert().into(Post.class)
.using(p)
.fetch()
.one()
.map(m -> (Integer) m.get("id"));
}
public Mono<Integer> update(Post p) {
return this.databaseClient.update()
.table(Post.class)
.using(p)
.fetch()
.rowsUpdated();
}
public Mono<Integer> deleteById(Integer id) {
return this.databaseClient.delete().from(Post.class)
.matching(where("id").is(id))
.fetch()
.rowsUpdated();
}
}
The complete codes can be found in my Github.
- docker-compose.yaml serves MySQL, MS SQL, PostgreSQL servers.
- data-r2dbc A none Spring Boot sample using H2
- data-r2dbc-postgresql A none Spring Boot sample using PostgreSQL
-
boot-r2dbc A Spring Boot based sample using H2 and
DatabaseClient
. -
boot-data-r2dbc A Spring Boot based sample using H2 and
Repository
interface. -
boot-data-r2dbc-mysql A Spring Boot based sample using MySQL and
Repository
interface. -
boot-data-r2dbc-mssql A Spring Boot based sample using MSSQL and
Repository
interface. -
boot-data-r2dbc-postgresql A Spring Boot based sample using PostgresSQL and
Repository
interface.