err

Z:\devel\python_training\env\Scripts\python.exe Z:/devel/python_training/check_db_connection.py
Traceback (most recent call last):
  File "Z:\devel\python_training\env\lib\site-packages\pymysql\converters.py", line 20, in escape_item
    encoder = mapping[text_type]
KeyError: <class 'str'>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "Z:/devel/python_training/check_db_connection.py", line 7, in <module>
    somelist = db.get_contacts_in_group(Group(id='50'))
  File "<string>", line 2, in get_contacts_in_group
  File "Z:\devel\python_training\env\lib\site-packages\pony\orm\core.py", line 406, in new_func
    try: return func(*args, **kwargs)
  File "Z:\devel\python_training\fixture\orm.py", line 56, in get_contacts_in_group
    return self.convert_contacts_to_model(orm_group.contacts)
  File "Z:\devel\python_training\fixture\orm.py", line 43, in convert_contacts_to_model
    return list(map(convert, contacts))
  File "<string>", line 2, in __iter__
  File "Z:\devel\python_training\env\lib\site-packages\pony\utils\utils.py", line 58, in cut_traceback
    return func(*args, **kwargs)
  File "Z:\devel\python_training\env\lib\site-packages\pony\orm\core.py", line 2989, in __iter__
    return iter(wrapper.copy())
  File "<string>", line 2, in copy
  File "Z:\devel\python_training\env\lib\site-packages\pony\utils\utils.py", line 58, in cut_traceback
    return func(*args, **kwargs)
  File "Z:\devel\python_training\env\lib\site-packages\pony\orm\core.py", line 2880, in copy
    return wrapper._attr_.copy(wrapper._obj_)
  File "Z:\devel\python_training\env\lib\site-packages\pony\orm\core.py", line 2628, in copy
GET CONNECTION FROM THE LOCAL POOL
SELECT `g`.`group_id`, `g`.`group_name`, `g`.`group_header`, `g`.`group_footer`
FROM `group_list` `g`
WHERE `g`.`group_id` = %s
['50']

SELECT `T1`.`id`
FROM `address_in_groups` `T1`
WHERE `T1`.`group_id` = %s
[50]

ROLLBACK
RELEASE CONNECTION
    if setdata is None or not setdata.is_fully_loaded: setdata = attr.load(obj)
  File "Z:\devel\python_training\env\lib\site-packages\pony\orm\core.py", line 2557, in load
    cursor = database._exec_sql(sql, arguments)
  File "Z:\devel\python_training\env\lib\site-packages\pony\orm\core.py", line 696, in _exec_sql
    connection = cache.reconnect(e)
  File "Z:\devel\python_training\env\lib\site-packages\pony\orm\core.py", line 1504, in reconnect
    if not provider.should_reconnect(exc): reraise(*sys.exc_info())
  File "Z:\devel\python_training\env\lib\site-packages\pony\utils\utils.py", line 85, in reraise
    try: raise exc.with_traceback(tb)
  File "Z:\devel\python_training\env\lib\site-packages\pony\orm\core.py", line 694, in _exec_sql
    try: new_id = provider.execute(cursor, sql, arguments, returning_id)
  File "<string>", line 2, in execute
  File "Z:\devel\python_training\env\lib\site-packages\pony\orm\dbapiprovider.py", line 48, in wrap_dbapi_exceptions
    try: return func(provider, *args, **kwargs)
  File "Z:\devel\python_training\env\lib\site-packages\pony\orm\dbapiprovider.py", line 240, in execute
    else: cursor.execute(sql, arguments)
  File "Z:\devel\python_training\env\lib\site-packages\pymysql\cursors.py", line 164, in execute
    query = self.mogrify(query, args)
  File "Z:\devel\python_training\env\lib\site-packages\pymysql\cursors.py", line 143, in mogrify
    query = query % self._escape_args(args, conn)
  File "Z:\devel\python_training\env\lib\site-packages\pymysql\cursors.py", line 118, in _escape_args
    return tuple(conn.literal(arg) for arg in args)
  File "Z:\devel\python_training\env\lib\site-packages\pymysql\cursors.py", line 118, in <genexpr>
    return tuple(conn.literal(arg) for arg in args)
  File "Z:\devel\python_training\env\lib\site-packages\pymysql\connections.py", line 800, in literal
    return self.escape(obj, self.encoders)
  File "Z:\devel\python_training\env\lib\site-packages\pymysql\connections.py", line 793, in escape
    return escape_item(obj, self.charset, mapping=mapping)
  File "Z:\devel\python_training\env\lib\site-packages\pymysql\converters.py", line 22, in escape_item
    raise TypeError("no default type converter defined")
TypeError: no default type converter defined

Process finished with exit code 1