Do not localize already localized pandas datetime #444

clickhouse_driver/columns/numpy/datetimecolumn.py

@@ -33,7 +33,9 @@ def apply_timezones_before_write(self, items):
             ts = items
         else:
             timezone = self.timezone if self.timezone else self.local_timezone
-            ts = pd.to_datetime(items).tz_localize(timezone)
+            ts = pd.to_datetime(items)
+            if not getattr(ts.dtype, 'tz', None):
+                ts = ts.tz_localize(timezone)
 
         ts = ts.tz_convert('UTC')
         return ts.tz_localize(None).to_numpy(self.datetime_dtype)

tests/numpy/columns/test_datetime.py

@@ -655,6 +655,29 @@ def test_read_tz_naive_column_with_client_timezone(self):
                         self.make_numpy_d64ns([self.dt_str] * 2)
                     )
 
+    @require_server_version(1, 1, 54337)
+    def test_do_not_localize_already_localized(self):
+        # Insert datetime with timezone Asia/Kamchatka
+        # into column with no timezone
+        # using server's timezone (Europe/Moscow)
+        with patch_env_tz('Asia/Novosibirsk'):
+            with self.create_table(self.table_columns()):
+                self.client.execute(
+                    'INSERT INTO test (a) VALUES',
+                    [np.array([pd.Timestamp('2017-07-14 05:40:00+1200')])],
+                    columnar=True
+                )
+
+                self.emit_cli(
+                    "INSERT INTO test (a) VALUES "
+                    "(toDateTime('2017-07-14 05:40:00', 'Asia/Kamchatka'))",
+                )
+
+                query = 'SELECT toInt32(a) FROM test'
+                inserted = self.emit_cli(query)
+                # 1499967600 = 1500000000 - 12 * 3600
+                self.assertEqual(inserted, '1499967600\n1499967600\n')
+
 
 class DateTime64TimezonesTestCase(DateTimeTimezonesTestCase):
     dt_type = 'DateTime64'