[Backport 2.x] Fixing issue when tracktotalhits is disabled (#372)

CHANGELOG.md

@@ -15,6 +15,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ### Fixed
 - Fix missing Highlight and SourceConfig in the MultisearchBody ([#442](https://github.com/opensearch-project/opensearch-java/pull/442))
+- Fix search failure with missing required property HitsMetadata.total when trackTotalHits is disabled ([#372](https://github.com/opensearch-project/opensearch-java/pull/372))
 
 ### Security
 

java-client/src/main/java/org/opensearch/client/opensearch/core/search/HitsMetadata.java

@@ -56,6 +56,7 @@
 
 
 public class HitsMetadata<T> implements JsonpSerializable {
+	@Nullable
 	private final TotalHits total;
 
 	private final List<Hit<T>> hits;
@@ -70,7 +71,7 @@ public class HitsMetadata<T> implements JsonpSerializable {
 
 	private HitsMetadata(Builder<T> builder) {
 
-		this.total = ApiTypeHelper.requireNonNull(builder.total, this, "total");
+		this.total = builder.total;
 		this.hits = ApiTypeHelper.unmodifiableRequired(builder.hits, this, "hits");
 		this.maxScore = builder.maxScore;
 		this.tSerializer = builder.tSerializer;
@@ -82,7 +83,7 @@ public static <T> HitsMetadata<T> of(Function<Builder<T>, ObjectBuilder<HitsMeta
 	}
 
 	/**
-	 * Required - API name: {@code total}
+	 * API name: {@code total}
 	 */
 	public final TotalHits total() {
 		return this.total;
@@ -114,8 +115,10 @@ public void serialize(JsonGenerator generator, JsonpMapper mapper) {
 
 	protected void serializeInternal(JsonGenerator generator, JsonpMapper mapper) {
 
-		generator.writeKey("total");
-		this.total.serialize(generator, mapper);
+		if (this.total != null) {
+			generator.writeKey("total");
+			this.total.serialize(generator, mapper);
+		}
 
 		if (ApiTypeHelper.isDefined(this.hits)) {
 			generator.writeKey("hits");
@@ -142,6 +145,7 @@ protected void serializeInternal(JsonGenerator generator, JsonpMapper mapper) {
 	 */
 
 	public static class Builder<T> extends ObjectBuilderBase implements ObjectBuilder<HitsMetadata<T>> {
+		@Nullable
 		private TotalHits total;
 
 		private List<Hit<T>> hits;
@@ -153,15 +157,15 @@ public static class Builder<T> extends ObjectBuilderBase implements ObjectBuilde
 		private JsonpSerializer<T> tSerializer;
 
 		/**
-		 * Required - API name: {@code total}
+		 * API name: {@code total}
 		 */
 		public final Builder<T> total(TotalHits value) {
 			this.total = value;
 			return this;
 		}
 
 		/**
-		 * Required - API name: {@code total}
+		 * API name: {@code total}
 		 */
 		public final Builder<T> total(Function<TotalHits.Builder, ObjectBuilder<TotalHits>> fn) {
 			return this.total(fn.apply(new TotalHits.Builder()).build());

java-client/src/test/java/org/opensearch/client/opensearch/integTest/AbstractRequestIT.java

@@ -58,6 +58,7 @@
 import org.opensearch.client.opensearch.core.search.CompletionSuggester;
 import org.opensearch.client.opensearch.core.search.FieldSuggester;
 import org.opensearch.client.opensearch.core.search.FieldSuggesterBuilders;
+import org.opensearch.client.opensearch.core.search.Hit;
 import org.opensearch.client.opensearch.core.search.Suggester;
 import org.opensearch.client.opensearch.indices.CreateIndexResponse;
 import org.opensearch.client.opensearch.indices.GetIndexResponse;
@@ -314,6 +315,37 @@ public void testBulkRequest() throws IOException {
         assertEquals(42, javaClient().get(b -> b.index("foo").id("abc"), AppData.class).source().getIntValue());
     }
 
+    @Test
+    public void testTrackTotalHitsFalse() throws Exception {
+        // https://github.com/opensearch-project/opensearch-java/issues/354
+        String index = "ingest-test";
+
+        javaClient().indices().create(b -> b.index(index));
+
+        AppData appData = new AppData();
+        appData.setIntValue(1337);
+        appData.setMsg("foo");
+
+        javaClient().index(b -> b
+                .index(index)
+                .id("myId")
+                .document(appData)
+                .refresh(Refresh.True) // Make it visible for search
+        ).id();
+
+        // Search
+        SearchResponse<AppData> search = javaClient().search(b -> b
+                        .index(index)
+                        .trackTotalHits(t -> t.enabled(false))
+                , AppData.class
+        );
+
+        List<Hit<AppData>> hits = search.hits().hits();
+        AppData appDataResult = search.hits().hits().get(0).source();
+        assertEquals(1337, appDataResult.getIntValue());
+        assertEquals("foo", appDataResult.getMsg());
+    }
+
     @Test
     public void testRefresh() throws IOException {
         AppData appData = new AppData();