Enable include_named_queries_score to be used in msearch

CHANGELOG.md

@@ -5,6 +5,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## [Unreleased 3.x]
 ### Added
+- Add support for include_named_queries_score in msearch ([#19102](https://github.com/opensearch-project/OpenSearch/issues/19102))
 - Use Lucene `pack` method for `half_float` and `usigned_long` when using `ApproximatePointRangeQuery`.
 
 ### Changed

server/src/main/java/org/opensearch/rest/action/search/RestMultiSearchAction.java

@@ -144,6 +144,11 @@ public static MultiSearchRequest parseRequest(
             maxConcurrentShardRequests = null;
         }
 
+        Boolean includeNamedQueriesScore = null;
+        if (restRequest.hasParam("include_named_queries_score")) {
+            includeNamedQueriesScore = restRequest.paramAsBoolean("include_named_queries_score", false);
+        }
+
         parseMultiLineRequest(restRequest, multiRequest.indicesOptions(), allowExplicitIndex, (searchRequest, parser) -> {
             searchRequest.source(SearchSourceBuilder.fromXContent(parser, false));
             RestSearchAction.checkRestTotalHits(restRequest, searchRequest);
@@ -171,6 +176,13 @@ public static MultiSearchRequest parseRequest(
             if (request.getCancelAfterTimeInterval() == null) {
                 request.setCancelAfterTimeInterval(cancelAfterTimeInterval);
             }
+
+            // If the `include_named_queries_score` URL parameter is set on the msearch request but not in the individual
+            // search body, copy it to the individual request's search body. The search body parameter determines whether
+            // the scores are computed during query execution.
+            if (includeNamedQueriesScore != null && request.source().includeNamedQueriesScore() == null) {
+                request.source().includeNamedQueriesScores(includeNamedQueriesScore);
+            }
         }
         return multiRequest;
     }

server/src/main/java/org/opensearch/search/SearchHit.java

@@ -64,7 +64,6 @@
 import org.opensearch.index.mapper.MapperService;
 import org.opensearch.index.mapper.SourceFieldMapper;
 import org.opensearch.index.seqno.SequenceNumbers;
-import org.opensearch.rest.action.search.RestSearchAction;
 import org.opensearch.search.fetch.subphase.highlight.HighlightField;
 import org.opensearch.search.lookup.SourceLookup;
 import org.opensearch.transport.RemoteClusterAware;
@@ -731,8 +730,8 @@ public XContentBuilder toInnerXContent(XContentBuilder builder, Params params) t
         }
         sortValues.toXContent(builder, params);
         if (!matchedQueries.isEmpty()) {
-            boolean includeMatchedQueriesScore = params.paramAsBoolean(RestSearchAction.INCLUDE_NAMED_QUERIES_SCORE_PARAM, false);
-            if (includeMatchedQueriesScore) {
+            boolean includeNamedQueriesScore = matchedQueries.values().stream().anyMatch(value -> value != null && !Float.isNaN(value));
+            if (includeNamedQueriesScore) {
                 builder.startObject(Fields.MATCHED_QUERIES);
                 for (Map.Entry<String, Float> entry : matchedQueries.entrySet()) {
                     builder.field(entry.getKey(), entry.getValue());

server/src/main/java/org/opensearch/search/SearchService.java

@@ -1559,7 +1559,9 @@ private void parseSource(DefaultSearchContext context, SearchSourceBuilder sourc
             }
         }
         context.trackScores(source.trackScores());
-        context.includeNamedQueriesScore(source.includeNamedQueriesScore());
+        if (source.includeNamedQueriesScore() != null) {
+            context.includeNamedQueriesScore(source.includeNamedQueriesScore());
+        }
         if (source.trackTotalHitsUpTo() != null
             && source.trackTotalHitsUpTo() != SearchContext.TRACK_TOTAL_HITS_ACCURATE
             && context.scrollContext() != null) {

server/src/main/java/org/opensearch/search/builder/SearchSourceBuilder.java

@@ -625,16 +625,16 @@ public SearchSourceBuilder trackScores(boolean trackScores) {
      * Applies when there are named queries, to return the scores along as well
      * Defaults to {@code false}.
      */
-    public SearchSourceBuilder includeNamedQueriesScores(boolean includeNamedQueriesScore) {
+    public SearchSourceBuilder includeNamedQueriesScores(Boolean includeNamedQueriesScore) {
         this.includeNamedQueriesScore = includeNamedQueriesScore;
         return this;
     }
 
     /**
      * Indicates whether scores will be returned as part of every search matched query.s
      */
-    public boolean includeNamedQueriesScore() {
-        return includeNamedQueriesScore != null && includeNamedQueriesScore;
+    public Boolean includeNamedQueriesScore() {
+        return includeNamedQueriesScore;
     }
 
     /**

server/src/test/java/org/opensearch/action/search/MultiSearchRequestTests.java

@@ -37,6 +37,7 @@
 import org.opensearch.common.CheckedBiConsumer;
 import org.opensearch.common.CheckedRunnable;
 import org.opensearch.common.logging.DeprecationLogger;
+import org.opensearch.common.settings.Settings;
 import org.opensearch.common.unit.TimeValue;
 import org.opensearch.common.xcontent.XContentHelper;
 import org.opensearch.common.xcontent.XContentType;
@@ -56,6 +57,7 @@
 import org.opensearch.rest.RestRequest;
 import org.opensearch.rest.action.search.RestMultiSearchAction;
 import org.opensearch.search.Scroll;
+import org.opensearch.search.SearchModule;
 import org.opensearch.search.builder.SearchSourceBuilder;
 import org.opensearch.test.OpenSearchTestCase;
 import org.opensearch.test.StreamsUtils;
@@ -196,6 +198,63 @@ public void testDefaultIndicesOptions() throws IOException {
         );
     }
 
+    public void testIncludeNamedQueriesScore() throws Exception {
+        SearchModule searchModule = new SearchModule(Settings.EMPTY, Collections.emptyList());
+        NamedXContentRegistry xContentRegistry = new NamedXContentRegistry(searchModule.getNamedXContents());
+
+        // URL query parameter: include_named_queries_score
+        assertIncludeNamedQueriesScore("", "false", false, true);
+
+        // URL query parameter: include_named_queries_score=true
+        assertIncludeNamedQueriesScore("true", "false", false, true);
+
+        // URL query parameter: include_named_queries_score=false
+        assertIncludeNamedQueriesScore("false", "true", true, false);
+
+        // No URL query parameter
+        assertIncludeNamedQueriesScore(null, "true", true, null);
+    }
+
+    private void assertIncludeNamedQueriesScore(
+        String urlParamValue,
+        String bodyParamValue,
+        Boolean expectedFirstRequest,
+        Boolean expectedSecondRequest
+    ) throws IOException {
+        SearchModule searchModule = new SearchModule(Settings.EMPTY, Collections.emptyList());
+        NamedXContentRegistry xContentRegistry = new NamedXContentRegistry(searchModule.getNamedXContents());
+
+        final String requestContent = "{\"index\":\"test\"}\r\n"
+            + "{\"query\":{\"term\":{\"field\":{\"value\":\"xxx\",\"_name\":\"value_name\"}}},\"include_named_queries_score\":"
+            + bodyParamValue
+            + "}\r\n"
+            + "{}\r\n"
+            + "{\"query\":{\"term\":{\"field\":{\"value\":\"xxx\",\"_name\":\"value_name\"}}}}\r\n";
+
+        FakeRestRequest.Builder builder = new FakeRestRequest.Builder(xContentRegistry).withContent(
+            new BytesArray(requestContent),
+            MediaTypeRegistry.JSON
+        );
+        if (urlParamValue != null) {
+            builder = builder.withParams(Collections.singletonMap("include_named_queries_score", urlParamValue));
+        }
+
+        FakeRestRequest restRequest = builder.build();
+        MultiSearchRequest request = RestMultiSearchAction.parseRequest(restRequest, null, true);
+
+        assertThat(request.requests().size(), equalTo(2));
+        assertEquals(
+            "First request's include_named_queries_score did not match",
+            expectedFirstRequest,
+            request.requests().get(0).source().includeNamedQueriesScore()
+        );
+        assertEquals(
+            "Second request's include_named_queries_score did not match",
+            expectedSecondRequest,
+            request.requests().get(1).source().includeNamedQueriesScore()
+        );
+    }
+
     public void testSimpleAdd2() throws Exception {
         MultiSearchRequest request = parseMultiSearchRequestFromFile("/org/opensearch/action/search/simple-msearch2.json");
         assertThat(request.requests().size(), equalTo(5));