variable in try clause not accessible in finally clause - python

Question

I am new to python, so sorry if this question is dumb, but can someone tell me what's going on here.

When I run the following code with no errors in the mdb.connect() call, the code runs fine.

But when I purposely insert an error (for example, put in 'localhostblahblah'), I get a 'NameError: name 'con' is not defined' error when I execute.

I thought that variables defined in the try clause should be accessible in the finally clause. What's going on?

#!/usr/bin/python

import MySQLdb as mdb
import sys

try:
    con = mdb.connect('localhost','jmtoung','','ptb_genetics')

except mdb.Error, e:
    print "Error"
    sys.exit(1)

finally:
    if con:
        con.close()

Answer 1

If mdb.connect errors, there's nothing to assign to con, so it doesn't get defined.

Instead of finally, try using else, which is run only when there was no exception. Docs

try:
    con = mdb.connect('localhost','jmtoung','','ptb_genetics')

except mdb.Error as e:
    print "Error"
    sys.exit(1)

else:  # else instead of finally
    con.close()