Default value for column doesn`t work

[Mikkgn]

I've found, that default column value doesnt work in aiomysql. For example, here is a table definition:

from datetime import datetime

import sqlalchemy as sa

metadata = sa.MetaData()

data_source_table = sa.Table(
    'data_source',
    metadata,
    sa.Column('id', UUID, nullable=False, primary_key=True, default=uuid.uuid4),
    sa.Column('source_box_id', UUID, nullable=False, index=True),
    sa.Column('updated_at', sa.dialects.mysql.DATETIME(fsp=6), nullable=False, default=datetime.utcnow),
)

And executing following code:

await db_conn.execute(
                data_source_table.insert().values(source_box_id=box_id)
            )

we get actual behavior with this error:

  File "/test/run.py", line 216, in execute
    data_source_table.insert().values(source_box_id=box_id)
  File "/usr/local/lib/python3.7/site-packages/aiomysql/sa/connection.py", line 173, in _execute
    await cursor.execute(str(compiled), post_processed_params)
  File "/usr/local/lib/python3.7/site-packages/aiomysql/cursors.py", line 239, in execute
    await self._query(query)
  File "/usr/local/lib/python3.7/site-packages/aiomysql/cursors.py", line 457, in _query
    await conn.query(q)
  File "/usr/local/lib/python3.7/site-packages/aiomysql/connection.py", line 428, in query
    await self._read_query_result(unbuffered=unbuffered)
  File "/usr/local/lib/python3.7/site-packages/aiomysql/connection.py", line 622, in _read_query_result
    await result.read()
  File "/usr/local/lib/python3.7/site-packages/aiomysql/connection.py", line 1105, in read
    first_packet = await self.connection._read_packet()
  File "/usr/local/lib/python3.7/site-packages/aiomysql/connection.py", line 593, in _read_packet
    packet.check_error()
  File "/usr/local/lib/python3.7/site-packages/pymysql/protocol.py", line 220, in check_error
    err.raise_mysql_exception(self._data)
  File "/usr/local/lib/python3.7/site-packages/pymysql/err.py", line 109, in raise_mysql_exception
    raise errorclass(errno, errval)
pymysql.err.IntegrityError: (1048, "Column 'id' cannot be null")

Expected behavior:
aiomysql should insert default values from the column.default property

Package versions:

• sqlalchemy==1.3.11
• pymysql==0.9.2
• aiomysql==0.0.20