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add crud guide.
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‎README.md

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@@ -6,6 +6,8 @@ Sample codes of RSocket Java and Spring RSocket integration.
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[Using Rsocket with Spring Boot](./docs/GUIDE.md)([medium's link](https://medium.com/@hantsy/using-rsocket-with-spring-boot-cfc67924d06a))
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[Building a CRUD application with RSocket and Spring](./docs/crud.md)
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## Sample Codes
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* **vanilla** rsocket-java sample

‎crud/server/pom.xml

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<properties>
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<java.version>11</java.version>
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</properties>
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<!-- <dependencyManagement>-->
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<!-- <dependencies>-->
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<!-- <dependency>-->
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<!-- <groupId>org.springframework.boot.experimental</groupId>-->
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<!-- <artifactId>spring-boot-bom-r2dbc</artifactId>-->
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<!-- <version>0.1.0.BUILD-SNAPSHOT</version>-->
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<!-- <type>pom</type>-->
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<!-- <scope>import</scope>-->
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<!-- </dependency>-->
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<!-- </dependencies>-->
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<!-- </dependencyManagement>-->
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<dependencies>
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<dependency>
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<groupId>org.springframework.boot</groupId>

‎crud/server/src/main/java/com/example/demo/DemoApplication.java

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import org.springframework.data.r2dbc.connectionfactory.init.ConnectionFactoryInitializer;
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import org.springframework.data.r2dbc.connectionfactory.init.ResourceDatabasePopulator;
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import org.springframework.data.r2dbc.repository.Query;
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import org.springframework.data.r2dbc.repository.R2dbcRepository;
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import org.springframework.data.relational.core.mapping.Column;
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import org.springframework.data.relational.core.mapping.Table;
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import org.springframework.data.repository.reactive.ReactiveCrudRepository;
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}
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interface PostRepository extends ReactiveCrudRepository<Post, Integer> {
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interface PostRepository extends R2dbcRepository<Post, Integer> {
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@Query("SELECT * FROM posts WHERE title like $1")
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Flux<Post> findByTitleContains(String name);

‎docs/crud.md

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# Creating a CRUD application with Spring RSocket
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# Building a CRUD application with RSocket and Spring
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In [the last post](https://medium.com/@hantsy/using-rsocket-with-spring-boot-cfc67924d06a), we explored the basic RSocket support in Spring and Spring Boot. In this post, we will create a CRUD application which is more close to the real world applications.
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We will create a *client* and *server* applications to demonstrate the interactions between RSocket client and server side.
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Firstly let's create the server application.
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You can simply generate a project template from [Spring initialzr](https://start.spring.io), set the following properties.
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* Build: Maven
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* Java: 11
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* Spring Boot version: 2.3.0.M3(I preferred the new version for practicing new techniques)
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* Dependencies: RSocket, Spring Data R2dbc, H2 Database, Lombok
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> If you are new to Spring Data R2dbc, check the post [ Accessing RDBMS with Spring Data R2dbc](https://medium.com/@hantsy/reactive-accessing-rdbms-with-spring-data-r2dbc-d6e453f2837e).
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In the server application, we will use RSocket to serve a RSocket server via TCP protocol.
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Open the *src/main/resources/application.properties*.
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```properties
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spring.rsocket.server.port=7000
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spring.rsocket.server.transport=tcp
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```
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Like what I have done in the former posts, firstly create a simple POJO.
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```java
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@Data
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@ToString
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@Builder
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@NoArgsConstructor
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@AllArgsConstructor
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@Table("posts")
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class Post {
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@Id
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@Column("id")
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private Integer id;
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@Column("title")
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private String title;
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@Column("content")
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private String content;
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}
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```
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And create a simple Repository for `Post`.
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```java
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interface PostRepository extends R2dbcRepository<Post, Integer> {
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}
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```
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Create a `Controller` class to handle the request meassages.
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```java
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@Controller
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@RequiredArgsConstructor
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class PostController {
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private final PostRepository posts;
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@MessageMapping("posts.findAll")
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public Flux<Post> all() {
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return this.posts.findAll();
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}
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@MessageMapping("posts.findById.{id}")
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public Mono<Post> get(@DestinationVariable("id") Integer id) {
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return this.posts.findById(id);
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}
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@MessageMapping("posts.save")
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public Mono<Post> create(@Payload Post post) {
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return this.posts.save(post);
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}
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@MessageMapping("posts.update.{id}")
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public Mono<Post> update(@DestinationVariable("id") Integer id, @Payload Post post) {
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return this.posts.findById(id)
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.map(p -> {
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p.setTitle(post.getTitle());
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p.setContent(post.getContent());
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return p;
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})
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.flatMap(p -> this.posts.save(p));
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}
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@MessageMapping("posts.deleteById.{id}")
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public Mono<Void> delete(@DestinationVariable("id") Integer id) {
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return this.posts.deleteById(id);
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}
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}
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```
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Create a `schema.sql` and a `data.sql` to create tables and initialize the data.
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```sql
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-- schema.sql
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CREATE TABLE posts (id SERIAL PRIMARY KEY, title VARCHAR(255), content VARCHAR(255));
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```
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```sql
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-- data.sql
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DELETE FROM posts;
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INSERT INTO posts (title, content) VALUES ('post one in data.sql', 'content of post one in data.sql');
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```
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> Note: In the Spring 2.3.0.M3, Spring Data R2dbc is merged in the Spring Data release train. But unfornately, the `ConnectionFactoryInitializer` is NOT ported.
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To make the the `schema.sql` and `data.sql` is loaded and executed at the application startup, declare a `ConnectionFactoryInitializer` bean.
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```java
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@Bean
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public ConnectionFactoryInitializer initializer(ConnectionFactory connectionFactory) {
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ConnectionFactoryInitializer initializer = new ConnectionFactoryInitializer();
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initializer.setConnectionFactory(connectionFactory);
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CompositeDatabasePopulator populator = new CompositeDatabasePopulator();
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populator.addPopulators(new ResourceDatabasePopulator(new ClassPathResource("schema.sql")));
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populator.addPopulators(new ResourceDatabasePopulator(new ClassPathResource("data.sql")));
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initializer.setDatabasePopulator(populator);
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return initializer;
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}
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```
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Now, you can start the server application.
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```bash
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mvn spring-boot:run
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```
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Next, let's move to the client application.
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Similarly, generate a project template from [Spring Initalizr](https://start.spring.io), in the *Dependencies* area, make sure you have choose *WebFlux*, *RSocket*, *Lombok*.
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The client application is a generic Webflux application, but use `RSocketRequester` to shake hands with the RSocket Servser.
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Declare a `RSocketRequester` bean.
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```java
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@Bean
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public RSocketRequester rSocketRequester(RSocketRequester.Builder b) {
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return b.dataMimeType(MimeTypeUtils.APPLICATION_JSON)
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.connectTcp("localhost", 7000)
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.block();
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}
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```
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Create a generic `RestController` and use the `RSocketRequester` to communicate with the RSocket server.
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```java
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@Slf4j
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@RequiredArgsConstructor
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@RestController()
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@RequestMapping("/posts")
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class PostClientController {
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private final RSocketRequester requester;
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@GetMapping("")
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Flux<Post> all() {
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return this.requester.route("posts.findAll")
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.retrieveFlux(Post.class);
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}
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@GetMapping("{id}")
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Mono<Post> findById(@PathVariable Integer id) {
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return this.requester.route("posts.findById." + id)
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.retrieveMono(Post.class);
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}
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@PostMapping("")
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Mono<Post> save(@RequestBody Post post) {
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return this.requester.route("posts.save")
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.data(post)
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.retrieveMono(Post.class);
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}
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@PutMapping("{id}")
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Mono<Post> update(@PathVariable Integer id, @RequestBody Post post) {
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return this.requester.route("posts.update."+ id)
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.data(post)
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.retrieveMono(Post.class);
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}
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@DeleteMapping("{id}")
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Mono<Void> delete(@PathVariable Integer id) {
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return this.requester.route("posts.deleteById."+ id).send();
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}
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}
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```
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Create a POJO `Post` to present the message payload transfered between client and server side.
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```java
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@Data
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@ToString
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@Builder
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@NoArgsConstructor
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@AllArgsConstructor
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class Post {
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private Integer id;
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private String title;
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private String content;
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}
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```
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Start up the client application.
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Try to test the CRUD opertaions by curl.
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```bash
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts
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# curl http://localhost:8080/posts
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[{"id":1,"title":"post one in data.sql","content":"content of post one in data.sql"},{"id":2,"title":"Post one","content":"The content of post one"},{"id":3,"title":"Post tow","content":"The content of post tow"}]
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts/1
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{"id":1,"title":"post one in data.sql","content":"content of post one in data.sql"}
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts/3
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{"id":3,"title":"Post tow","content":"The content of post tow"}
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts/2
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{"id":2,"title":"Post one","content":"The content of post one"}
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts -d '{"title":"my save title", "content":"my content of my post"}'
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{"timestamp":"2020-03-13T11:09:52.653+0000","path":"/posts","status":500,"error":"Internal Server Error","message":"In a WebFlux application, form data is accessed via ServerWebExchange.getFormData().","requestId":"efbd0803-5"}curl: (3) [globbing] unmatched close brace/bracket in column 30
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts -d '{"title":"my save title", "content":"my content of my post"}' -H "Content-Type:application/json"
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{"timestamp":"2020-03-13T11:10:18.814+0000","path":"/posts","status":400,"error":"Bad Request","message":"Failed to read HTTP message","requestId":"b02c8cb9-6"}curl: (3) [globbing] unmatched close brace/bracket in column 30
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# curl http://localhost:8080/posts/1
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{"id":1,"title":"post one in data.sql","content":"content of post one in data.sql"}
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts -d '{"title":"my save title", "content":"my content of my post"}' -H "Content-Type:application/json" -X POST
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{"timestamp":"2020-03-13T11:11:07.798+0000","path":"/posts","status":400,"error":"Bad Request","message":"Failed to read HTTP message","requestId":"96dca4ed-7"}curl: (3) [globbing] unmatched close brace/bracket in column 30
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# curl http://localhost:8080/posts/3
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{"id":3,"title":"Post tow","content":"The content of post tow"}
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts -d \"{\"title\":\"my save title\", \"content\":\"my content of my post\"}\" -H "Content-Type:application/json" -X POST
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{"timestamp":"2020-03-13T11:12:49.995+0000","path":"/posts","status":400,"error":"Bad Request","message":"Failed to read HTTP message","requestId":"52bb940b-8"}curl: (6) Could not resolve host: save
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curl: (6) Could not resolve host: title",
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curl: (3) Port number ended with '"'
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curl: (6) Could not resolve host: content
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curl: (6) Could not resolve host: of
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curl: (6) Could not resolve host: my
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curl: (3) [globbing] unmatched close brace/bracket in column 6
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# curl http://localhost:8080/posts/2
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{"id":2,"title":"Post one","content":"The content of post one"}
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts -d "{\"title\":\"my save title\", \"content\":\"my content of my post\"}" -H "Content-Type:application/json" -X POST
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# curl http://localhost:8080/posts -d "{\"title\":\"my save title\", \"content\":\"my content of my post\"}" -H "Content-Type:application/json" -X POST
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{"id":4,"title":"my save title","content":"my content of my post"}
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts/4 -d "{\"title\":\"my save title\", \"content\":\"update my content of my post\"}" -H "Content-Type:application/json" -X PUT
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{"id":4,"title":"my save title","content":"update my content of my post"}
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts
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# curl http://localhost:8080/posts
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[{"id":1,"title":"post one in data.sql","content":"content of post one in data.sql"},{"id":2,"title":"Post one","content":"The content of post one"},{"id":3,"title":"Post tow","content":"The content of post tow"},{"id":4,"title":"my save title","content":"update my content of my post"}]
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts/4 -X DELETE
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts
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# curl http://localhost:8080/posts/4 -X DELETE
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# curl http://localhost:8080/posts
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[{"id":1,"title":"post one in data.sql","content":"content of post one in data.sql"},{"id":2,"title":"Post one","content":"The content of post one"},{"id":3,"title":"Post tow","content":"The content of post tow"}]
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D:\hantsylabs\rsocket-sample\integration\server-boot>curl http://localhost:8080/posts
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```
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As a bonus, try to add a filter to find the posts by keyword.
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In the server application, create a new method in the `PostRepository`.
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```java
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@Query("SELECT * FROM posts WHERE title like $1")
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Flux<Post> findByTitleContains(String name);
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```
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And create a new route to handle this request from client.
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```java
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class PostController {
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//...
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@MessageMapping("posts.titleContains")
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public Flux<Post> titleContains(@Payload String title) {
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return this.posts.findByTitleContains(title);
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}
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//...
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}
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```
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In the client side, change the `PostClientController` 's `all` method to the following:
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```java
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class PostClientController {
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//...
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Flux<Post> all(@RequestParam(name = "title", required = false) String title) {
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if (StringUtils.hasText(title)) {
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return this.requester.route("posts.titleContains")
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.data(title).retrieveFlux(Post.class);
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} else {
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return this.requester.route("posts.findAll")
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.retrieveFlux(Post.class);
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}
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}
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//...
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}
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```
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Now, try to add a `title` request param to access http://localhost:8080/posts.
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Get the [source codes](https://github.com/hantsy/rsocket-sample/tree/master/crud) from my Github.

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