Support element filter search for struct field

sdk-core/src/main/java/io/milvus/param/ParamUtils.java

@@ -727,6 +727,10 @@ public UpsertRequest buildUpsertRequest() {
 
     @SuppressWarnings("unchecked")
     public static ByteString convertPlaceholder(List<?> vectors, PlaceholderType placeType) throws ParamException {
+        return convertPlaceholder(vectors, placeType, false);
+    }
+
+    public static ByteString convertPlaceholder(List<?> vectors, PlaceholderType placeType, boolean elementLevel) throws ParamException {
         PlaceholderType plType = PlaceholderType.None;
         List<ByteString> byteStrings = new ArrayList<>();
         for (Object vector : vectors) {
@@ -771,7 +775,8 @@ public static ByteString convertPlaceholder(List<?> vectors, PlaceholderType pla
 
         PlaceholderValue.Builder pldBuilder = PlaceholderValue.newBuilder()
                 .setTag(Constant.VECTOR_TAG)
-                .setType(plType);
+                .setType(plType)
+                .setElementLevel(elementLevel);
         byteStrings.forEach(pldBuilder::addValues);
 
         PlaceholderValue plv = pldBuilder.build();

sdk-core/src/main/java/io/milvus/v2/service/vector/response/SearchResp.java

@@ -103,13 +103,15 @@ public static class SearchResult {
         private Object id;
         private String primaryKey;
         private Map<String, HighlightResult> highlightResults;
+        private Long elementOffset;
 
         private SearchResult(SearchResultBuilder builder) {
             this.entity = builder.entity;
             this.score = builder.score;
             this.id = builder.id;
             this.primaryKey = builder.primaryKey;
             this.highlightResults = builder.highlightResults == null ? new HashMap<>() : builder.highlightResults;
+            this.elementOffset = builder.elementOffset;
         }
 
         public static SearchResultBuilder builder() {
@@ -161,10 +163,19 @@ public void addHighlightResult(String fieldName, HighlightResult highlightResult
             this.highlightResults.put(fieldName, highlightResult);
         }
 
+        public Long getElementOffset() {
+            return elementOffset;
+        }
+
+        public void setElementOffset(Long elementOffset) {
+            this.elementOffset = elementOffset;
+        }
+
         @Override
         public String toString() {
             return "{" + getPrimaryKey() + ": " + getId() + ", Score: " + getScore() + ", OutputFields: " + entity +
-                    (MapUtils.isEmpty(highlightResults) ? "" : (", HighlightResults: " + highlightResults)) + "}";
+                    (MapUtils.isEmpty(highlightResults) ? "" : (", HighlightResults: " + highlightResults)) +
+                    (elementOffset == null ? "" : (", ElementOffset: " + elementOffset)) + "}";
         }
 
         public static class SearchResultBuilder {
@@ -173,6 +184,7 @@ public static class SearchResultBuilder {
             private Object id;
             private String primaryKey = "id";
             private Map<String, HighlightResult> highlightResults = new HashMap<>();
+            private Long elementOffset;
 
             public SearchResultBuilder entity(Map<String, Object> entity) {
                 this.entity = entity;
@@ -205,6 +217,11 @@ public SearchResultBuilder addHighlightResult(String fieldName, HighlightResult
                 return this;
             }
 
+            public SearchResultBuilder elementOffset(Long elementOffset) {
+                this.elementOffset = elementOffset;
+                return this;
+            }
+
             public SearchResult build() {
                 return new SearchResult(this);
             }

sdk-core/src/main/java/io/milvus/v2/utils/ConvertUtils.java

@@ -106,7 +106,7 @@ public List<List<SearchResp.SearchResult>> getEntities(SearchResults response) {
                         .build());
             }
 
-            // set highlight
+            // set highlight and element offset
             SearchResultsWrapper.Position position = searchResultsWrapper.getOffsetByIndex(i);
             long offset = position.getOffset();
             long k = position.getK();
@@ -127,6 +127,14 @@ public List<List<SearchResp.SearchResult>> getEntities(SearchResults response) {
                 }
             }
 
+            // set element offset
+            if (response.getResults().hasElementIndices()) {
+                LongArray elementIndices = response.getResults().getElementIndices();
+                for (long j = 0; j < k; j++) {
+                    singleResults.get((int) j).setElementOffset(elementIndices.getData((int) (offset + j)));
+                }
+            }
+
             searchResults.add(singleResults);
         }
         return searchResults;

sdk-core/src/main/java/io/milvus/v2/utils/VectorUtils.java

@@ -148,15 +148,16 @@ private static long getGuaranteeTimestamp(ConsistencyLevel consistencyLevel, Str
         }
     }
 
-    private static ByteString convertPlaceholder(List<Object> data, PlaceholderType placeType) {
+    private static ByteString convertPlaceholder(List<Object> data, PlaceholderType placeType, boolean elementLevel) {
         if (placeType == PlaceholderType.VarChar) {
             List<ByteString> byteStrings = new ArrayList<>();
             for (Object obj : data) {
                 byteStrings.add(ByteString.copyFrom(((String) obj).getBytes()));
             }
             PlaceholderValue.Builder pldBuilder = PlaceholderValue.newBuilder()
                     .setTag(Constant.VECTOR_TAG)
-                    .setType(placeType);
+                    .setType(placeType)
+                    .setElementLevel(elementLevel);
             byteStrings.forEach(pldBuilder::addValues);
 
             PlaceholderValue plv = pldBuilder.build();
@@ -166,14 +167,14 @@ private static ByteString convertPlaceholder(List<Object> data, PlaceholderType
             return placeholderGroup.toByteString();
         } else {
             try {
-                return ParamUtils.convertPlaceholder(data, placeType);
+                return ParamUtils.convertPlaceholder(data, placeType, elementLevel);
             } catch (ParamException e) {
                 throw new MilvusClientException(ErrorCode.INVALID_PARAMS, e.getMessage());
             }
         }
     }
 
-    private static void convertSearchTarget(SearchReq request, SearchRequest.Builder builder) {
+    private static void convertSearchTarget(SearchReq request, SearchRequest.Builder builder, boolean elementLevel) {
         // prepare target, the input could be:
         // 1. vectors or string list for doc-in-doc-out
         // 2. ids list for search by primary keys
@@ -200,7 +201,7 @@ private static void convertSearchTarget(SearchReq request, SearchRequest.Builder
                 data.add(vector.getData());
             }
 
-            ByteString byteStr = convertPlaceholder(data, plType);
+            ByteString byteStr = convertPlaceholder(data, plType, elementLevel);
             builder.setPlaceholderGroup(byteStr);
             builder.setNq(vectors.size());
         } else {
@@ -246,7 +247,9 @@ public SearchRequest ConvertToGrpcSearchRequest(SearchReq request) {
         }
 
         // target vectors or ids
-        convertSearchTarget(request, builder);
+        String filter = request.getFilter();
+        boolean elementLevel = filter != null && filter.contains("element_filter");
+        convertSearchTarget(request, builder, elementLevel);
 
         // search parameters
         // tries to fit the compatibility between v2.5.1 and older versions
@@ -515,7 +518,7 @@ public static SearchRequest convertAnnSearchParam(AnnSearchReq annSearchReq,
             data.add(vector.getData());
         }
 
-        ByteString byteStr = convertPlaceholder(data, plType);
+        ByteString byteStr = convertPlaceholder(data, plType, false);
         builder.setPlaceholderGroup(byteStr);
         builder.setNq(vectors.size());