DemoApplication.java

package com.example.demo;

import lombok.Builder;
import lombok.Data;
import lombok.ToString;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Profile;
import org.springframework.data.annotation.Id;
import org.springframework.data.elasticsearch.annotations.Document;
import org.springframework.data.elasticsearch.annotations.Field;
import org.springframework.data.elasticsearch.annotations.FieldType;
import org.springframework.data.elasticsearch.repository.ReactiveElasticsearchRepository;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.*;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

}

@Component
@Slf4j
@Profile("default")
class DataInitializer implements CommandLineRunner {

    private final PostRepository posts;

    public DataInitializer(PostRepository posts) {
        this.posts = posts;
    }

    @Override
    public void run(String[] args) {
        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...")
                );

    }

}

@RestController()
@RequestMapping(value = "/posts")
class PostController {

    private final PostRepository posts;

    public PostController(PostRepository posts) {
        this.posts = 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 String id) {
        return this.posts.findById(id);
    }

    @PutMapping("/{id}")
    public Mono<Post> update(@PathVariable String id, @RequestBody Post post) {
        return this.posts.findById(id)
                .map(p -> {
                    p.setTitle(post.getTitle());
                    p.setContent(post.getContent());

                    return p;
                })
                .flatMap(this.posts::save);
    }

    @DeleteMapping("/{id}")
    public Mono<Void> delete(@PathVariable String id) {
        return this.posts.deleteById(id);
    }

}

interface PostRepository extends ReactiveElasticsearchRepository<Post, String> {
}

@Document(indexName = "posts")
@Data
@ToString
@Builder
class Post {
    @Id
    private String id;

    @Field(store = true, type = FieldType.Text, fielddata = true)
    private String title;

    @Field(store = true, type = FieldType.Text, fielddata = true)
    private String content;
}