Spring Data ElasticSearch

ElasticSearch is well known as a search engine, also working well as document based NoSQL.

Spring Data ElasticSearch adds basic Reactive support.

Generate a project skeleton from Spring Intializr.

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
</dependency>

Create a Post class to present a document in ElasticSearch, and add a @Document annotation on the class level.

@Data
@ToString
@Builder
@NoArgsConstructor
@AllArgsConstructor
@Document
class Post {

    @Id
    private String id;
    private String title;

    @Field("content")
    private String content;

}

Create PostRepository interface.

interface PostRepository extends ReactiveElasticsearchRepository<Post, String> {
}

For the complete codes, check spring-reactive-sample/boot-data-elasticsearch.

Add some sample data via a CommandLineRunner bean or a ApplicationRunner bean.

public void init() {
    log.info("start data initialization  ...");
    this.posts
        .deleteAll()
        .thenMany(
            Flux
                .just("Post one", "Post two")
                .flatMap(
                    title -> this.posts.save(Post.builder().title(title).content("content of " + title).build())
                )
        )
        .log()
        .subscribe(
            null,
            null,
            () -> log.info("done initialization...")
        );

}

To run the application, you have to serve a running ElasticSearch server firstly.

docker-compose up elasticsearch