[Tutor] Trying to catch an exception...

[Kent Johnson]

William O'Higgins Witteman wrote:
> I am running a program (via py2exe) that is reading some XML files with
> xml.minidom.  I am getting an error wherein I pull a value from a tag
> which (I think) happens to be empty.  Thus, it throws this error:
> 
> AttributeError: 'NoneType' object has no attribute 'data'
> 
> Here's the code that creates this problem:
> 
> def functionname(fileobject):
>   try:
>     xmldoc = minidom.parse(fileobject)
>   except xml.parsers.expat.ExpatError, AttributeError:

This should be written,
   except (xml.parsers.expat.ExpatError, AttributeError):

The parentheses are important. The way you have written it, an instance 
of ExpatError, if it occurs, will be bound to the name AttributeError; 
AttributeErrors will not be caught at all.

Kent

>     logit = "There is a malformed file: " + fileobject + "\n"
>     logfile.write(logit)
>   else:
>     a = xmldoc.getElementsByTagName('date_modified')
>     try:
>       b = a[0].firstChild.data
>     except xml.parsers.expat.ExpatError, AttributeError:
>       logit = "There is a malformed file: " + fileobject + "\n"
>       logfile.write(logit)
> 
> I am wondering what I have to do to catch this exception - I'm assuming
> that the problem is that "a" is an empty object, and so it has not
> attributes.  Thanks.