Trapping MySQL Warnings In Python

Question

I would like to catch and log MySQL warnings in Python. For example, MySQL issues a warning to standard error if you submit 'DROP DATABASE IF EXISTS database_of_armaments' when no such database exists. I would like to catch this and log it, but even in the try/else syntax the warning message still appears.

The try/except syntax does catch MySQL errors (eg, submission of a typo like 'DRP DATABASE database_of_armaments' ).

I have experimented with <<except.MySQLdb.Warning>> -- no luck. I've looked at the warnings module, but don't understand how to incorporate it into the try/else syntax.

To be concrete, how do I get the following (or something like it) to work.

GIVEN: database 'database_of_armaments' does not exist.

try:
    cursor.execute('DROP DATABASE IF EXISTS database_of_armaments')
except: <<WHAT DO I PUT HERE?>>
    print 'There was a MySQL warning.' 
    <<AND what goes here if I want to get and manipulate information about the warning?>>

UPDATE:

Thanks for the comments. I had tried these and they didn't work -- but I had been using a DatabaseConnection class that I wrote for a connection, and its runQuery() method to execute. When I created a connection and cursor outside the class, the try/except Exception caught the "Programming Error", and except MySQLdb.ProgrammingError worked as advertised.

So now I have to figure out what is wrong with my class coding.

Thank you for your help.

Answer 1

Follow these steps.

1. Run it with except Exception, e: print repr(e) .

2. See what exception you get.

3. Change the Exception to the exception you actually got.

Also, remember that the exception, e, is an object. You can print dir(e) , e.__class__.__name__ , etc.to see what attributes it has.

Also, you can do this interactively at the >>> prompt in Python. You can then manipulate the object directly -- no guessing.

Answer 2

Have you tried something like this?

try:
    cursor.execute(some_statement)
except MySQLdb.IntegrityError, e: 
    # handle a specific error condition
except MySQLdb.Error, e:
    # handle a generic error condition
except MySQLdb.Warning, e:
    # handle warnings, if the cursor you're using raises them

Answer 3

I think the exception you want to catch is a MySQLdb.ProgrammingError, and to get information about it, just add a variable to store the error data (a tuple) in after that ie:

try:
    cursor.execute('DROP DATABASE IF EXISTS database_of_armaments')
except MySQLdb.ProgrammingError, e:
    print 'There was a MySQL warning.  This is the info we have about it: %s' %(e) 

Answer 4

I managed to trap the mysql warning like this:

import _mysql_exceptions

try:
    foo.bar()
except _mysql_exceptions.Warning, e:
    pass

Answer 5

first you should turn on warnings to treat as exceptions, and only then you can catch them. see "error" warnings filter - https://docs.python.org/3/library/warnings.html#the-warnings-filter

Answer 6

Plain and simple

def log_warnings(curs):
    for msg in curs.messages:
        if msg[0] == MySQLdb.Warning:
            logging.warn(msg[1])

cursor.execute('DROP DATABASE IF EXISTS database_of_armaments')
log_warnings(cursor)

msg[1] example :- (u'Warning', 1366L, u"Incorrect integer value: '\\xa3' for column 'in_userid' at row 1")