Parse result field data when result set entry count is not zero (#624)

Since empty field data has no info for fieldName nor field type
it's more meaningful to skip parse field data for empty resultSet

This PR adds ResultCount check before performing fieldData parsing
When resultSet is empty, the entry shall have no error with empty fields
See also #623

Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>

client/data.go

@@ -80,13 +80,17 @@ func (c *GrpcClient) Search(ctx context.Context, collName string, partitions []s
 			ResultCount: rc,
 			Scores:      results.GetScores()[offset : offset+rc],
 		}
-		entry.IDs, entry.Err = entity.IDColumns(results.GetIds(), offset, offset+rc)
-		if entry.Err != nil {
-			offset += rc
-			continue
+		// parse result set if current nq is not empty
+		if rc > 0 {
+			entry.IDs, entry.Err = entity.IDColumns(results.GetIds(), offset, offset+rc)
+			if entry.Err != nil {
+				offset += rc
+				continue
+			}
+			entry.Fields, entry.Err = c.parseSearchResult(schema, outputFields, fieldDataList, i, offset, offset+rc)
+			sr = append(sr, entry)
 		}
-		entry.Fields, entry.Err = c.parseSearchResult(schema, outputFields, fieldDataList, i, offset, offset+rc)
-		sr = append(sr, entry)
+
 		offset += rc
 	}
 	return sr, nil