[Sqlalchemy-tickets] Issue #4223: TypeError when trying to connect to mysql using pyodbc (zzzeek/sqlalchemy)

[Dmitriy S. <iss...@bi...>]

New issue 4223: TypeError when trying to connect to mysql using pyodbc
https://bitbucket.org/zzzeek/sqlalchemy/issues/4223/typeerror-when-trying-to-connect-to-mysql

Dmitriy Shashkin:

python 3.6, 64 bit, fedora 27, sqlalchemy 1.2.5, mysql 5.7

When trying to connect to mysql using pyodbc I get the following error: TypeError: The first argument to execute must be a string or unicode query.

This problem does not exist in 1.1.18, it was introduced in 1.2.0

Code to reproduce error (requires and existing mysql database):
```
import sqlalchemy
sqlalchemy.create_engine('mysql+pyodbc://dsn').connect()
```

The text of error message:

```
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-6-2a6312fe45dd> in <module>()
----> 1 sqlalchemy.create_engine('mysql+pyodbc://replica_lan_mob_api_stats').connect()

~/.local/lib/python3.6/site-packages/sqlalchemy/engine/base.py in connect(self, **kwargs)
   2100         """
   2101 
-> 2102         return self._connection_cls(self, **kwargs)
   2103 
   2104     def contextual_connect(self, close_with_result=False, **kwargs):

~/.local/lib/python3.6/site-packages/sqlalchemy/engine/base.py in __init__(self, engine, connection, close_with_result, _branch_from, _execution_options, _dispatch, _has_events)
     88         else:
     89             self.__connection = connection \
---> 90                 if connection is not None else engine.raw_connection()
     91             self.__transaction = None
     92             self.__savepoint_seq = 0

~/.local/lib/python3.6/site-packages/sqlalchemy/engine/base.py in raw_connection(self, _connection)
   2186         """
   2187         return self._wrap_pool_connect(
-> 2188             self.pool.unique_connection, _connection)
   2189 
   2190 

~/.local/lib/python3.6/site-packages/sqlalchemy/engine/base.py in _wrap_pool_connect(self, fn, connection)
   2156         dialect = self.dialect
   2157         try:
-> 2158             return fn()
   2159         except dialect.dbapi.Error as e:
   2160             if connection is None:

~/.local/lib/python3.6/site-packages/sqlalchemy/pool.py in unique_connection(self)
    343 
    344         """
--> 345         return _ConnectionFairy._checkout(self)
    346 
    347     def _create_connection(self):

~/.local/lib/python3.6/site-packages/sqlalchemy/pool.py in _checkout(cls, pool, threadconns, fairy)
    782     def _checkout(cls, pool, threadconns=None, fairy=None):
    783         if not fairy:
--> 784             fairy = _ConnectionRecord.checkout(pool)
    785 
    786             fairy._pool = pool

~/.local/lib/python3.6/site-packages/sqlalchemy/pool.py in checkout(cls, pool)
    530     @classmethod
    531     def checkout(cls, pool):
--> 532         rec = pool._do_get()
    533         try:
    534             dbapi_connection = rec.get_connection()

~/.local/lib/python3.6/site-packages/sqlalchemy/pool.py in _do_get(self)
   1187             except:
   1188                 with util.safe_reraise():
-> 1189                     self._dec_overflow()
   1190         else:
   1191             return self._do_get()

~/.local/lib/python3.6/site-packages/sqlalchemy/util/langhelpers.py in __exit__(self, type_, value, traceback)
     64             self._exc_info = None   # remove potential circular references
     65             if not self.warn_only:
---> 66                 compat.reraise(exc_type, exc_value, exc_tb)
     67         else:
     68             if not compat.py3k and self._exc_info and self._exc_info[1]:

~/.local/lib/python3.6/site-packages/sqlalchemy/util/compat.py in reraise(tp, value, tb, cause)
    185         if value.__traceback__ is not tb:
    186             raise value.with_traceback(tb)
--> 187         raise value
    188 
    189 else:

~/.local/lib/python3.6/site-packages/sqlalchemy/pool.py in _do_get(self)
   1184         if self._inc_overflow():
   1185             try:
-> 1186                 return self._create_connection()
   1187             except:
   1188                 with util.safe_reraise():

~/.local/lib/python3.6/site-packages/sqlalchemy/pool.py in _create_connection(self)
    348         """Called by subclasses to create a new ConnectionRecord."""
    349 
--> 350         return _ConnectionRecord(self)
    351 
    352     def _invalidate(self, connection, exception=None, _checkin=True):

~/.local/lib/python3.6/site-packages/sqlalchemy/pool.py in __init__(self, pool, connect)
    475         self.__pool = pool
    476         if connect:
--> 477             self.__connect(first_connect_check=True)
    478         self.finalize_callback = deque()
    479 

~/.local/lib/python3.6/site-packages/sqlalchemy/pool.py in __connect(self, first_connect_check)
    675                 pool.dispatch.first_connect.\
    676                     for_modify(pool.dispatch).\
--> 677                     exec_once(self.connection, self)
    678             if pool.dispatch.connect:
    679                 pool.dispatch.connect(self.connection, self)

~/.local/lib/python3.6/site-packages/sqlalchemy/event/attr.py in exec_once(self, *args, **kw)
    272                 if not self._exec_once:
    273                     try:
--> 274                         self(*args, **kw)
    275                     finally:
    276                         self._exec_once = True

~/.local/lib/python3.6/site-packages/sqlalchemy/event/attr.py in __call__(self, *args, **kw)
    282             fn(*args, **kw)
    283         for fn in self.listeners:
--> 284             fn(*args, **kw)
    285 
    286     def __len__(self):

~/.local/lib/python3.6/site-packages/sqlalchemy/util/langhelpers.py in go(*arg, **kw)
   1332         if once:
   1333             once_fn = once.pop()
-> 1334             return once_fn(*arg, **kw)
   1335 
   1336     return go

~/.local/lib/python3.6/site-packages/sqlalchemy/engine/strategies.py in first_connect(dbapi_connection, connection_record)
    181                                     _has_events=False)
    182                 c._execution_options = util.immutabledict()
--> 183                 dialect.initialize(c)
    184             event.listen(pool, 'first_connect', first_connect, once=True)
    185 

~/.local/lib/python3.6/site-packages/sqlalchemy/dialects/mysql/base.py in initialize(self, connection)
   1902                     "CHECK constraints, which impact handling of NULL values "
   1903                     "with SQLAlchemy's boolean datatype (MDEV-13596). An "
-> 1904                     "additional issue prevents proper migrations of columns "
   1905                     "with CHECK constraints (MDEV-11114).  Please upgrade to "
   1906                     "MariaDB 10.2.9 or greater, or use the MariaDB 10.1 "

~/.local/lib/python3.6/site-packages/sqlalchemy/dialects/mysql/pyodbc.py in _detect_charset(self, connection)
     59         # If it's decided that issuing that sort of SQL leaves you SOL, then
     60         # this can prefer the driver value.
---> 61         rs = connection.execute("SHOW VARIABLES LIKE 'character_set%%'")
     62         opts = {row[0]: row[1] for row in self._compat_fetchall(rs)}
     63         for key in ('character_set_connection', 'character_set'):

~/.local/lib/python3.6/site-packages/sqlalchemy/engine/base.py in execute(self, object, *multiparams, **params)
    940         """
    941         if isinstance(object, util.string_types[0]):
--> 942             return self._execute_text(object, multiparams, params)
    943         try:
    944             meth = object._execute_on_connection

~/.local/lib/python3.6/site-packages/sqlalchemy/engine/base.py in _execute_text(self, statement, multiparams, params)
   1102             statement,
   1103             parameters,
-> 1104             statement, parameters
   1105         )
   1106         if self._has_events or self.engine._has_events:

~/.local/lib/python3.6/site-packages/sqlalchemy/engine/base.py in _execute_context(self, dialect, constructor, statement, parameters, *args)
   1198                 parameters,
   1199                 cursor,
-> 1200                 context)
   1201 
   1202         if self._has_events or self.engine._has_events:

~/.local/lib/python3.6/site-packages/sqlalchemy/engine/base.py in _handle_dbapi_exception(self, e, statement, parameters, cursor, context)
   1414                 )
   1415             else:
-> 1416                 util.reraise(*exc_info)
   1417 
   1418         finally:

~/.local/lib/python3.6/site-packages/sqlalchemy/util/compat.py in reraise(tp, value, tb, cause)
    185         if value.__traceback__ is not tb:
    186             raise value.with_traceback(tb)
--> 187         raise value
    188 
    189 else:

~/.local/lib/python3.6/site-packages/sqlalchemy/engine/base.py in _execute_context(self, dialect, constructor, statement, parameters, *args)
   1191                         statement,
   1192                         parameters,
-> 1193                         context)
   1194         except BaseException as e:
   1195             self._handle_dbapi_exception(

~/.local/lib/python3.6/site-packages/sqlalchemy/engine/default.py in do_execute(self, cursor, statement, parameters, context)
    505 
    506     def do_execute(self, cursor, statement, parameters, context=None):
--> 507         cursor.execute(statement, parameters)
    508 
    509     def do_execute_no_params(self, cursor, statement, context=None):

TypeError: The first argument to execute must be a string or unicode query.
```