[Backport 2.6] fix: extend protobuf after flush vector cache (#3200) (#3201)

Backport of #3200 to `2.6`.

Signed-off-by: silas.jiang <silas.jiang@zilliz.com>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: jac <jacllovey@qq.com>
Co-authored-by: silas.jiang <silas.jiang@zilliz.com>

Author: 3 people

pymilvus/client/prepare.py

@@ -1016,8 +1016,6 @@ def _parse_upsert_row_request(
                 )
 
         fields_data = {k: v for k, v in fields_data.items() if field_len[k] > 0}
-        request.fields_data.extend(fields_data.values())
-
         # Flush all bytes vector field temporary byte lists to optimize memory usage
         for field_data in fields_data.values():
             if field_data.type in (
@@ -1028,6 +1026,8 @@ def _parse_upsert_row_request(
             ):
                 entity_helper.flush_vector_bytes(field_data, vector_bytes_cache)
 
+        request.fields_data.extend(fields_data.values())
+
         if struct_fields_data:
             # reconstruct the struct array fields data (same as in insert)
             for struct in input_struct_field_info:

tests/test_prepare.py

@@ -538,6 +538,35 @@ def test_batch_upsert_param_partial_update_field_count_validation_skip(self):
             request.fields_data) == 2, "Should only contain data for provided fields"
 
 
+
+    def test_row_upsert_param_partial_update_with_float16_vector_cached(self):
+        """Test that cached vector types (float16) are flushed correctly with partial_update=True"""
+        dim = 8
+        schema = CollectionSchema([
+             FieldSchema("float16_vector", DataType.FLOAT16_VECTOR, dim=dim),
+             FieldSchema("pk", DataType.INT64, is_primary=True)
+        ])
+        
+        # simulated float16 data (numpy float16 array)
+        vector_data = np.zeros((1, dim), dtype=np.float16)
+        
+        rows = [
+            {"pk": 1, "float16_vector": vector_data[0]}
+        ]
+        
+        req = Prepare.row_upsert_param("test_collection", rows, "", 
+                                     fields_info=schema.to_dict()["fields"], 
+                                     partial_update=True)
+        
+        vector_field_data = next((fd for fd in req.fields_data if fd.field_name == "float16_vector"), None)
+        assert vector_field_data is not None, "Vector field 'float16_vector' not found in request"
+
+        # Should have data
+        # 1 vector * 8 dim * 2 bytes = 16 bytes
+        expected_bytes = 1 * dim * 2
+        assert len(vector_field_data.vectors.float16_vector) == expected_bytes, f"Vector data has incorrect size! Expected {expected_bytes} bytes."
+
+
 class TestCreateIndexRequest:
     def test_create_index_request_with_false_boolean_param(self):
         """Test that boolean False values are preserved in index parameters"""