fix: Fixed serialization of DataFrame with empty values #118

Author: rolincova

tests/test_WriteApiDataFrame.py

@@ -101,10 +101,13 @@ def test_write_nan(self):
                                   columns=["actual_kw_price", "forecast_kw_price", "actual_general_use",
                                            "forecast_general_use"])
 
-        points = self.client.write_api(write_options=SYNCHRONOUS)\
-            ._data_frame_to_list_of_points(data_frame=data_frame,
-                                           precision=None,
-                                           data_frame_measurement_name='measurement')
+        self.client.default_tags = None
+
+        write_api = self.client.write_api(write_options=SYNCHRONOUS)
+
+        points = write_api._data_frame_to_list_of_points(data_frame=data_frame,
+                                                         precision=None,
+                                                         data_frame_measurement_name='measurement')
 
         self.assertEqual(4, len(points))
         self.assertEqual("measurement actual_kw_price=3.1955,actual_general_use=20.514305 1586044800000000000",
@@ -115,3 +118,5 @@ def test_write_nan(self):
                          points[2])
         self.assertEqual("measurement forecast_kw_price=5.139563,forecast_general_use=19.79124 1586050200000000000",
                          points[3])
+
+        write_api.__del__()