[Sqlalchemy-tickets] Issue #3943: engine.has_table() throws an error instead of returning False when a table does not exist (zzzeek/sqlalchemy)

[Nick H. <iss...@bi...>]

New issue 3943: engine.has_table() throws an error instead of returning False when a table does not exist
https://bitbucket.org/zzzeek/sqlalchemy/issues/3943/enginehas_table-throws-an-error-instead-of

Nick Hahner:

Hi there, 
I've got the following versions:
SQLAlchemy==1.1.6
mysql-connector==2.1.4

When running the following code I get an error:

```
#!python


import mysql.connector
from sqlalchemy import create_engine

engine = create_engine('mysql://',
                        creator=lambda: mysql.connector.connect(
                                            option_files='/Users/me/.mylogin.cnf'
                                            )
                      )

engine.has_table('table_that_exists', schema='my_schema')
# -> returns True

engine.has_table('table_that_does_not_exist', schema='my_schema')
---------------------------------------------------------------------------
ProgrammingError                          Traceback (most recent call last)
<ipython-input-18-c38b6b523753> in <module>()
----> 1 engine.has_table('table_that_does_not_exist',schema='my_schema')

/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in has_table(self, table_name, schema)
   2131
   2132         """
-> 2133         return self.run_callable(self.dialect.has_table, table_name, schema)
   2134
   2135     def _wrap_pool_connect(self, fn, connection):

/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in run_callable(self, callable_, *args, **kwargs)
   2034         """
   2035         with self.contextual_connect() as conn:
-> 2036             return conn.run_callable(callable_, *args, **kwargs)
   2037
   2038     def execute(self, statement, *multiparams, **params):

/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in run_callable(self, callable_, *args, **kwargs)
   1523
   1524         """
-> 1525         return callable_(self, *args, **kwargs)
   1526
   1527     def _run_visitor(self, visitorcallable, element, **kwargs):

/usr/local/lib/python2.7/site-packages/sqlalchemy/dialects/mysql/base.pyc in has_table(self, connection, table_name, schema)
   1659             try:
   1660                 rs = connection.execution_options(
-> 1661                     skip_user_error_events=True).execute(st)
   1662                 have = rs.fetchone() is not None
   1663                 rs.close()

/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in execute(self, object, *multiparams, **params)
    937         """
    938         if isinstance(object, util.string_types[0]):
--> 939             return self._execute_text(object, multiparams, params)
    940         try:
    941             meth = object._execute_on_connection

/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in _execute_text(self, statement, multiparams, params)
   1095             statement,
   1096             parameters,
-> 1097             statement, parameters
   1098         )
   1099         if self._has_events or self.engine._has_events:

/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in _execute_context(self, dialect, constructor, statement, parameters, *args)
   1187                 parameters,
   1188                 cursor,
-> 1189                 context)
   1190
   1191         if self._has_events or self.engine._has_events:

/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in _handle_dbapi_exception(self, e, statement, parameters, cursor, context)
   1394                 )
   1395             else:
-> 1396                 util.reraise(*exc_info)
   1397
   1398         finally:

/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in _execute_context(self, dialect, constructor, statement, parameters, *args)
   1180                         statement,
   1181                         parameters,
-> 1182                         context)
   1183         except BaseException as e:
   1184             self._handle_dbapi_exception(

/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/default.pyc in do_execute(self, cursor, statement, parameters, context)
    468
    469     def do_execute(self, cursor, statement, parameters, context=None):
--> 470         cursor.execute(statement, parameters)
    471
    472     def do_execute_no_params(self, cursor, statement, context=None):

/usr/local/lib/python2.7/site-packages/mysql/connector/cursor.pyc in execute(self, operation, params, multi)
    513         else:
    514             try:
--> 515                 self._handle_result(self._connection.cmd_query(stmt))
    516             except errors.InterfaceError:
    517                 if self._connection._have_next_result:  # pylint: disable=W0212

/usr/local/lib/python2.7/site-packages/mysql/connector/connection.pyc in cmd_query(self, query, raw, buffered, raw_as_string)
    486         if not isinstance(query, bytes):
    487             query = query.encode('utf-8')
--> 488         result = self._handle_result(self._send_cmd(ServerCmd.QUERY, query))
    489
    490         if self._have_next_result:

/usr/local/lib/python2.7/site-packages/mysql/connector/connection.pyc in _handle_result(self, packet)
    393             return self._handle_eof(packet)
    394         elif packet[4] == 255:
--> 395             raise errors.get_exception(packet)
    396
    397         # We have a text result set

ProgrammingError: 1146 (42S02): Table 'my_schema.table_that_does_not_exist' doesn't exist

```

the ~/.mylogin.cnf' file is an unencrypted config file https://dev.mysql.com/doc/refman/5.7/en/option-files.html