reactive-elasticsearch-operations.adoc

Reactive Elasticsearch Operations

ReactiveElasticsearchOperations is the gateway to executing high level commands against an Elasticsearch cluster using the ReactiveElasticsearchClient.

The ReactiveElasticsearchTemplate is the default implementation of ReactiveElasticsearchOperations.

Reactive Elasticsearch Template

To get started the ReactiveElasticsearchTemplate needs to know about the actual client to work with. Please see [elasticsearch.clients.reactive] for details on the client.

Reactive Template Configuration

The easiest way of setting up the ReactiveElasticsearchTemplate is via AbstractReactiveElasticsearchConfiguration providing dedicated configuration method hooks for base package, the initial entity set etc.

Example 1. The AbstractReactiveElasticsearchConfiguration

@Configuration
public class Config extends AbstractReactiveElasticsearchConfiguration {

  @Bean (1)
  @Override
  public ReactiveElasticsearchClient reactiveElasticsearchClient() {
      // ...
  }
}

1. Configure the client to use. This can be done by ReactiveRestClients or directly via DefaultReactiveElasticsearchClient.

Note	If applicable set default HttpHeaders via the ClientConfiguration of the ReactiveElasticsearchClient. See [elasticsearch.clients.configuration].

Tip	If needed the ReactiveElasticsearchTemplate can be configured with default RefreshPolicy and IndicesOptions that get applied to the related requests by overriding the defaults of refreshPolicy() and indicesOptions().

However one might want to be more in control over the actual components and use a more verbose approach.

Example 2. Configure the ReactiveElasticsearchTemplate

@Configuration
public class Config {

  @Bean (1)
  public ReactiveElasticsearchClient reactiveElasticsearchClient() {
    // ...
  }
  @Bean (2)
  public ElasticsearchConverter elasticsearchConverter() {
    return new MappingElasticsearchConverter(elasticsearchMappingContext());
  }
  @Bean (3)
  public SimpleElasticsearchMappingContext elasticsearchMappingContext() {
    return new SimpleElasticsearchMappingContext();
  }
  @Bean (4)
  public ReactiveElasticsearchOperations reactiveElasticsearchOperations() {
    return new ReactiveElasticsearchTemplate(reactiveElasticsearchClient(), elasticsearchConverter());
  }
}

1. Configure the client to use. This can be done by ReactiveRestClients or directly via DefaultReactiveElasticsearchClient.

2. Set up the ElasticsearchConverter used for domain type mapping utilizing metadata provided by the mapping context.

3. The Elasticsearch specific mapping context for domain type metadata.

4. The actual template based on the client and conversion infrastructure.

Reactive Template Usage

ReactiveElasticsearchTemplate lets you save, find and delete your domain objects and map those objects to documents stored in Elasticsearch.

Consider the following:

Example 3. Use the ReactiveElasticsearchTemplate

@Document(indexName = "marvel")
public class Person {

  private @Id String id;
  private String name;
  private int age;
  // Getter/Setter omitted...
}

template.save(new Person("Bruce Banner", 42))                    (1)
  .doOnNext(System.out::println)
  .flatMap(person -> template.findById(person.id, Person.class)) (2)
  .doOnNext(System.out::println)
  .flatMap(person -> template.delete(person))                    (3)
  .doOnNext(System.out::println)
  .flatMap(id -> template.count(Person.class))                   (4)
  .doOnNext(System.out::println)
  .subscribe(); (5)

The above outputs the following sequence on the console.

> Person(id=QjWCWWcBXiLAnp77ksfR, name=Bruce Banner, age=42)
> Person(id=QjWCWWcBXiLAnp77ksfR, name=Bruce Banner, age=42)
> QjWCWWcBXiLAnp77ksfR
> 0

1. Insert a new Person document into the marvel index under type characters. The id is generated on server side and set into the instance returned.

2. Lookup the Person with matching id in the marvel index under type characters.

3. Delete the Person with matching id, extracted from the given instance, in the marvel index under type characters.

4. Count the total number of documents in the marvel index under type characters.

5. Don’t forget to subscribe().