Fix KNNQuery Precision

Signed-off-by: luyuncheng <luyuncheng@bytedance.com>

Author: luyuncheng

java-client/src/main/java/org/opensearch/client/opensearch/_types/query_dsl/KnnQuery.java

@@ -9,6 +9,7 @@
 package org.opensearch.client.opensearch._types.query_dsl;
 
 import jakarta.json.stream.JsonGenerator;
+import java.math.BigDecimal;
 import java.util.function.Function;
 import javax.annotation.Nullable;
 import org.opensearch.client.json.JsonpDeserializable;
@@ -19,6 +20,8 @@
 import org.opensearch.client.util.ApiTypeHelper;
 import org.opensearch.client.util.ObjectBuilder;
 
+import static java.math.RoundingMode.HALF_UP;
+
 @JsonpDeserializable
 public class KnnQuery extends QueryBase implements QueryVariant {
     private final String field;
@@ -93,7 +96,9 @@ protected void serializeInternal(JsonGenerator generator, JsonpMapper mapper) {
         generator.writeKey("vector");
         generator.writeStartArray();
         for (float value : this.vector) {
-            generator.write(value);
+            BigDecimal b = new BigDecimal(value);
+            double T = b.setScale(6, HALF_UP).doubleValue();
+            generator.write(T);
         }
         generator.writeEnd();
 

java-client/src/test/java/org/opensearch/client/opensearch/_types/query_dsl/KnnQueryTest.java

@@ -11,4 +11,11 @@ public void toBuilder() {
 
         assertEquals(toJson(copied), toJson(origin));
     }
+
+    @Test
+    public void toBuilderPrecision() {
+        KnnQuery origin = new KnnQuery.Builder().field("field").vector(new float[] { 0.1f, 0.4f }).k(1).build();
+
+        assertEquals(toJson(origin), "{\"field\":{\"vector\":[0.1,0.4],\"k\":1}}");
+    }
 }

java-client/src/test/java/org/opensearch/client/opensearch/model/RequestEncodingTest.java

@@ -33,6 +33,7 @@
 package org.opensearch.client.opensearch.model;
 
 import org.junit.Test;
+import org.opensearch.client.json.jackson.JacksonJsonpMapper;
 import org.opensearch.client.json.jsonb.JsonbJsonpMapper;
 import org.opensearch.client.opensearch.core.SearchRequest;
 
@@ -61,4 +62,22 @@ public void testParametersNotInJson() {
         assertNull(request.q());
 
     }
+
+    @Test
+    public void testKnnVectorPrecision() {
+
+        float[] vector = {0.4f, 0.3f};
+        SearchRequest request = new SearchRequest.Builder().q("knn")
+                .query(q -> q.knn(k -> k.field("values").vector(vector).k(1)))
+                .build();
+
+        JacksonJsonpMapper mapper = new JacksonJsonpMapper();
+        String str = toJson(request, mapper);
+        assertEquals("{\"query\":{\"knn\":{\"values\":{\"vector\":[0.4,0.3],\"k\":1}}}}", str);
+
+        request = fromJson(str, SearchRequest.class, mapper);
+
+        assertTrue(request.query().isKnn());
+        assertNull(request.q());
+    }
 }