Date of null value cannot be inserted with using pandas.dataframe.to_sql

[wuhuanyan]

If I use pandas.dataframe.to_sql, insert the empty date value in dataframe to Clickhouse,There will be a mistake here.

code

def main():
    d2 = pd.DataFrame({
        'date': [pd.to_datetime('2018-01-01'), None, pd.to_datetime('2018-01-03')]
    })
    print(d2)
    """
            date
    0 2018-01-01
    1        NaT
    2 2018-01-03
    """
    ch_engine = sqla.create_engine(Const.CH_URI)
    d2.to_sql(name='t_date', con=ch_engine,
              if_exists='append', index=False)

error message

.............
  File "/anaconda3/envs/study/lib/python3.6/site-packages/clickhouse_driver/columns/service.py", line 80, in write_column
    column.write_data(items, buf)
  File "/anaconda3/envs/study/lib/python3.6/site-packages/clickhouse_driver/columns/base.py", line 79, in write_data
    self._write_data(items, buf)
  File "/anaconda3/envs/study/lib/python3.6/site-packages/clickhouse_driver/columns/base.py", line 82, in _write_data
    prepared = self.prepare_items(items)
  File "/anaconda3/envs/study/lib/python3.6/site-packages/clickhouse_driver/columns/base.py", line 69, in prepare_items
    x = before_write(x)
  File "/anaconda3/envs/study/lib/python3.6/site-packages/clickhouse_driver/columns/datetimecolumn.py", line 26, in before_write_item
    if value.tzinfo is None:
AttributeError: 'NoneType' object has no attribute 'tzinfo'

so,I edit 'clickhouse_driver/columns/datetimecolumn.py',such as:

    def before_write_item(self, value):
        if self.timezone:
            # Set server's timezone for offset-naive datetime.
            # if value.tzinfo is None:
            #     value = self.timezone.localize(value)
            # value = value.astimezone(utc)
            # return int(timegm(value.timetuple()))
            """
            my code
            """
            if hasattr(value, 'tzinfo'):
                if value.tzinfo is None:
                    value = self.timezone.localize(value)
                value = value.astimezone(utc)
                return int(timegm(value.timetuple()))
            else:
                return 0
        else:
            # If datetime is offset-aware use it's timezone.
            if value.tzinfo is not None:
                value = value.astimezone(utc)
                return int(timegm(value.timetuple()))

            return int(mktime(value.timetuple()))

Null date can also be inserted into Clickhouse (0000-00-00 00:00:00).