Cannot catch _mysql_exceptions.OperationalError

[Bob]

In our database code (we are using django v0.96) we wanted to catch
and handle MySQL OperationalErrors. We use both the Django models and
database connections.

However, even though we confirmed that a
_mysql_exceptions.OperationalError are raised (particularly 1213
deadlock), we cannot catch them with try/except.

Here's the code that did not work:

import _mysql_exceptions
from _mysql_exceptions import OperationalError

try:
database_code()
except (_mysql_exceptions.OperationalError, OperationalError), e:
error_handling()

Originally, we just had one import, but tried both to ensure that was
not the problem. In debugging, we confirmed that both type(e) and
e.__class_ were <class _mysql_exceptions.OperationalError>.

The only work-around we found was:

try:
database_code()
except Exception, e:
if e.__class__.__name__.find('OperationalError') != -1:
error_handling()
else:
raise

This seems silly. If we used any other exception, the except clause
seems to work correctly.

Is there a problem with _mysql_exceptions.OperationalError? Is there
a better work-around?

Thanks,
Bob

[John Nagle]

Bob wrote:

In our database code (we are using django v0.96) we wanted to catch
and handle MySQL OperationalErrors. We use both the Django models and
database connections.

However, even though we confirmed that a
_mysql_exceptions.OperationalError are raised (particularly 1213
deadlock), we cannot catch them with try/except.

If you're using MySQLdb, it works fine:

try:
... do database operations
except MySQLdb.OperationalError, message: # handle trouble
errorcode = message[0] # get MySQL error code
if errorcode == kmysqlduplicateentry : # if dup on insert
... deal with duplicate entry

If Django has a problem, you'll have to take that up with them.

John Nagle

[Jeffrey Froman]

Bob wrote:

Here's the code that did not work:

import _mysql_exceptions
from _mysql_exceptions import OperationalError

try:
database_code()
except (_mysql_exceptions.OperationalError, OperationalError), e:
error_handling()

Both of the above forms work fine here, as does using
MySQLdb.OperationalError:
------------------------------------------------

>>import MySQLdb
try:

.... db = MySQLdb.connect(user='jeffrey', host='localhost')
.... except MySQLdb.OperationalError:
.... print 'caught'
....
caught

>>import _mysql_exceptions
try:

.... db = MySQLdb.connect(user='jeffrey', host='localhost')
.... except _mysql_exceptions.OperationalError:
.... print 'caught'
....
caught

>>from _mysql_exceptions import OperationalError
try:

.... db = MySQLdb.connect(user='jeffrey', host='localhost')
.... except OperationalError:
.... print 'caught'
....
caught

>>MySQLdb.OperationalError is _mysql_exceptions.OperationalError

True

>>MySQLdb.__version__

'1.2.2'
------------------------------------------------
Jeffrey