DATAES-680 - ReactiveElasticsearchTemplate-should-use-the-count-API.

src/main/java/org/springframework/data/elasticsearch/client/reactive/DefaultReactiveElasticsearchClient.java

@@ -47,7 +47,6 @@
 import org.apache.http.util.EntityUtils;
 import org.elasticsearch.ElasticsearchStatusException;
 import org.elasticsearch.action.ActionRequest;
-import org.elasticsearch.action.ActionResponse;
 import org.elasticsearch.action.admin.indices.close.CloseIndexRequest;
 import org.elasticsearch.action.admin.indices.create.CreateIndexRequest;
 import org.elasticsearch.action.admin.indices.delete.DeleteIndexRequest;
@@ -79,6 +78,8 @@
 import org.elasticsearch.action.update.UpdateRequest;
 import org.elasticsearch.action.update.UpdateResponse;
 import org.elasticsearch.client.Request;
+import org.elasticsearch.client.core.CountRequest;
+import org.elasticsearch.client.core.CountResponse;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.xcontent.DeprecationHandler;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
@@ -328,6 +329,17 @@ public Mono<DeleteResponse> delete(HttpHeaders headers, DeleteRequest deleteRequ
 				.publishNext();
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.elasticsearch.client.reactive.ReactiveElasticsearchClient#count(org.springframework.http.HttpHeaders, org.elasticsearch.action.search.SearchRequest)
+	 */
+	@Override
+	public Mono<Long> count(HttpHeaders headers, CountRequest countRequest) {
+		return sendRequest(countRequest, RequestCreator.count(), CountResponse.class, headers) //
+				.map(CountResponse::getCount) //
+				.next();
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.elasticsearch.client.reactive.ReactiveElasticsearchClient#ping(org.springframework.http.HttpHeaders, org.elasticsearch.action.search.SearchRequest)
@@ -572,13 +584,12 @@ private static GetResult getResponseToGetResult(GetResponse response) {
 
 	// -->
 
-	private <Req extends ActionRequest, Resp extends ActionResponse> Flux<Resp> sendRequest(Req request,
-			Function<Req, Request> converter, Class<Resp> responseType, HttpHeaders headers) {
+	private <Req extends ActionRequest, Resp> Flux<Resp> sendRequest(Req request, Function<Req, Request> converter,
+			Class<Resp> responseType, HttpHeaders headers) {
 		return sendRequest(converter.apply(request), responseType, headers);
 	}
 
-	private <AR extends ActionResponse> Flux<AR> sendRequest(Request request, Class<AR> responseType,
-			HttpHeaders headers) {
+	private <Resp> Flux<Resp> sendRequest(Request request, Class<Resp> responseType, HttpHeaders headers) {
 
 		String logId = ClientLogger.newLogId();
 
@@ -807,6 +818,10 @@ static Function<FlushRequest, Request> flushIndex() {
 			return RequestConverters::flushIndex;
 		}
 
+		static Function<CountRequest, Request> count() {
+			return RequestConverters::count;
+		}
+
 	}
 
 	/**

src/main/java/org/springframework/data/elasticsearch/client/reactive/ReactiveElasticsearchClient.java

@@ -43,6 +43,7 @@
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.update.UpdateRequest;
 import org.elasticsearch.action.update.UpdateResponse;
+import org.elasticsearch.client.core.CountRequest;
 import org.elasticsearch.index.get.GetResult;
 import org.elasticsearch.index.reindex.BulkByScrollResponse;
 import org.elasticsearch.index.reindex.DeleteByQueryRequest;
@@ -59,6 +60,7 @@
  *
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Peter-Josef Meisch
  * @author Henrique Amaral
  * @since 3.2
  * @see ClientConfiguration
@@ -331,6 +333,47 @@ default Mono<DeleteResponse> delete(DeleteRequest deleteRequest) {
 	 */
 	Mono<DeleteResponse> delete(HttpHeaders headers, DeleteRequest deleteRequest);
 
+	/**
+	 * Execute a {@link SearchRequest} against the {@literal count} API.
+	 *
+	 * @param consumer new {@literal null}.
+	 * @see <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/search-count.html">Count API on
+	 *      elastic.co</a>
+	 * @return the {@link Mono} emitting the count result.
+	 * @since 4.0
+	 */
+	default Mono<Long> count(Consumer<CountRequest> consumer) {
+
+		CountRequest countRequest = new CountRequest();
+		consumer.accept(countRequest);
+		return count(countRequest);
+	}
+
+	/**
+	 * Execute a {@link SearchRequest} against the {@literal count} API.
+	 *
+	 * @param countRequest must not be {@literal null}.
+	 * @see <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/search-count.html">Count API on
+	 *      elastic.co</a>
+	 * @return the {@link Mono} emitting the count result.
+	 * @since 4.0
+	 */
+	default Mono<Long> count(CountRequest countRequest) {
+		return count(HttpHeaders.EMPTY, countRequest);
+	}
+
+	/**
+	 * Execute a {@link SearchRequest} against the {@literal count} API.
+	 *
+	 * @param headers Use {@link HttpHeaders} to provide eg. authentication data. Must not be {@literal null}.
+	 * @param countRequest must not be {@literal null}.
+	 * @see <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/search-count.html">Count API on
+	 *      elastic.co</a>
+	 * @return the {@link Mono} emitting the count result.
+	 * @since 4.0
+	 */
+	Mono<Long> count(HttpHeaders headers, CountRequest countRequest);
+
 	/**
 	 * Execute a {@link SearchRequest} against the {@literal search} API.
 	 *

src/main/java/org/springframework/data/elasticsearch/client/util/RequestConverters.java

@@ -59,6 +59,7 @@
 import org.elasticsearch.client.Request;
 import org.elasticsearch.client.Requests;
 import org.elasticsearch.client.RethrottleRequest;
+import org.elasticsearch.client.core.CountRequest;
 import org.elasticsearch.client.indices.AnalyzeRequest;
 import org.elasticsearch.cluster.health.ClusterHealthStatus;
 import org.elasticsearch.common.Priority;
@@ -388,6 +389,32 @@ public static Request search(SearchRequest searchRequest) {
 		return request;
 	}
 
+	/**
+	 * Creates a count request.
+	 * 
+	 * @param countRequest the search defining the data to be counted
+	 * @return Elasticsearch count request
+	 * @since 4.0
+	 */
+	public static Request count(CountRequest countRequest) {
+		Request request = new Request(HttpMethod.POST.name(),
+				endpoint(countRequest.indices(), countRequest.types(), "_count"));
+
+		Params params = new Params(request);
+		addCountRequestParams(params, countRequest);
+
+		if (countRequest.source() != null) {
+			request.setEntity(createEntity(countRequest.source(), REQUEST_BODY_CONTENT_TYPE));
+		}
+		return request;
+	}
+
+	private static void addCountRequestParams(Params params, CountRequest countRequest) {
+		params.withRouting(countRequest.routing());
+		params.withPreference(countRequest.preference());
+		params.withIndicesOptions(countRequest.indicesOptions());
+	}
+
 	private static void addSearchRequestParams(Params params, SearchRequest searchRequest) {
 		params.putParam("typed_keys", "true");
 		params.withRouting(searchRequest.routing());