[Fix] add non-null check for queryBuilder in NeuralQueryEnricherProcessor

CHANGELOG.md

@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fixed exception for case when Hybrid query being wrapped into bool query ([#490](https://github.com/opensearch-project/neural-search/pull/490))
 - Hybrid query and nested type fields ([#498](https://github.com/opensearch-project/neural-search/pull/498))
 - Fix typo for sparse encoding processor factory([#578](https://github.com/opensearch-project/neural-search/pull/578))
+- Add non-null check for queryBuilder in NeuralQueryEnricherProcessor ([#615](https://github.com/opensearch-project/neural-search/pull/615))
 ### Infrastructure
 ### Documentation
 ### Maintenance

src/main/java/org/opensearch/neuralsearch/processor/NeuralQueryEnricherProcessor.java

@@ -67,7 +67,10 @@ private NeuralQueryEnricherProcessor(
     @Override
     public SearchRequest processRequest(SearchRequest searchRequest) {
         QueryBuilder queryBuilder = searchRequest.source().query();
-        queryBuilder.visit(new NeuralSearchQueryVisitor(modelId, neuralFieldDefaultIdMap));
+        /* Use null check for the case where users are using empty query body. i.e. GET /index_name/_search */
+        if (queryBuilder != null) {
+            queryBuilder.visit(new NeuralSearchQueryVisitor(modelId, neuralFieldDefaultIdMap));
+        }
         return searchRequest;
     }
 

src/test/java/org/opensearch/neuralsearch/processor/NeuralQueryEnricherProcessorIT.java

@@ -11,8 +11,14 @@
 import java.util.Collections;
 import java.util.Map;
 
+import org.apache.hc.core5.http.io.entity.EntityUtils;
 import org.junit.Before;
+import org.opensearch.client.Request;
+import org.opensearch.client.Response;
 import org.opensearch.common.settings.Settings;
+import org.opensearch.common.xcontent.XContentHelper;
+import org.opensearch.common.xcontent.XContentType;
+import org.opensearch.core.rest.RestStatus;
 import org.opensearch.neuralsearch.BaseNeuralSearchIT;
 import org.opensearch.neuralsearch.query.HybridQueryBuilder;
 import org.opensearch.neuralsearch.query.NeuralQueryBuilder;
@@ -55,6 +61,27 @@ public void testNeuralQueryEnricherProcessor_whenNoModelIdPassed_thenSuccess() {
         }
     }
 
+    @SneakyThrows
+    public void testNeuralQueryEnricherProcessor_whenGetEmptyQueryBody_thenSuccess() {
+        String modelId = null;
+        try {
+            initializeIndexIfNotExist(index);
+            modelId = prepareModel();
+            createSearchRequestProcessor(modelId, search_pipeline);
+            createPipelineProcessor(modelId, ingest_pipeline, ProcessorType.TEXT_EMBEDDING);
+            updateIndexSettings(index, Settings.builder().put("index.search.default_pipeline", search_pipeline));
+            Request request = new Request("POST", "/" + index + "/_search");
+            Response response = client().performRequest(request);
+            assertEquals(request.getEndpoint() + ": failed", RestStatus.OK, RestStatus.fromCode(response.getStatusLine().getStatusCode()));
+            String responseBody = EntityUtils.toString(response.getEntity());
+            Map<String, Object> responseInMap = XContentHelper.convertToMap(XContentType.JSON.xContent(), responseBody, false);
+            assertFalse(responseInMap.isEmpty());
+            assertEquals(3, ((Map) responseInMap.get("hits")).size());
+        } finally {
+            wipeOfTestResources(index, ingest_pipeline, modelId, search_pipeline);
+        }
+    }
+
     @SneakyThrows
     public void testNeuralQueryEnricherProcessor_whenHybridQueryBuilderAndNoModelIdPassed_thenSuccess() {
         String modelId = null;

src/test/java/org/opensearch/neuralsearch/processor/NeuralQueryEnricherProcessorTests.java

@@ -46,6 +46,17 @@ public void testProcessRequest_whenVisitingQueryBuilder_thenSuccess() throws Exc
         assertEquals(processSearchRequest, searchRequest);
     }
 
+    public void testProcessRequest_whenVisitingEmptyQueryBody_thenSuccess() throws Exception {
+        NeuralQueryEnricherProcessor.Factory factory = new NeuralQueryEnricherProcessor.Factory();
+        SearchRequest searchRequest = new SearchRequest();
+        searchRequest.source(new SearchSourceBuilder());
+        assertNull(searchRequest.source().query());
+        NeuralQueryEnricherProcessor processor = createTestProcessor(factory);
+        SearchRequest processSearchRequest = processor.processRequest(searchRequest);
+        // should do nothing
+        assertNull(processSearchRequest.source().query());
+    }
+
     public void testType() throws Exception {
         NeuralQueryEnricherProcessor.Factory factory = new NeuralQueryEnricherProcessor.Factory();
         NeuralQueryEnricherProcessor processor = createTestProcessor(factory);