[storm] Exception handling

[akira]

Hi all!

I am trying to handle exceptions returned from the DB API. For example, 
I have a UNIQUE constraint on a field, when I try to save an object that 
violates this I get this:

"duplicate key violates unique constraint"

So trying to handle the errors properly so that I can return the right 
error to the user I have done some testing:

 try:
            store.add(user)
            store.flush()          
 except Exception,e:
            print e.__class__.__name__       # this emits an 
"IntegrityError"
            print Exception.__str__(e)          # this print s"duplicate 
key violates unique constraint "users_username_key'"

            if Exception.__str__(e) == 'duplicate key violates unique 
constraint "users_username_key':
                print " this username has been taken....blablah" # This 
does not work
            if e.__class__.__name__  == 'IntegrityError":
                print " this username has been taken....blablah" # This 
works


Why does the first "if" conditional not work? Is this the right way to 
handle such a problem? Should I try to handle all the exceptions that 
might crop up? I am using postgresql, can I find all the defined 
Exceptional that I would like to handle there?


Thanks in advance