Python try except block does not recognize error type

Question

My scrpt has the following line:

libro_dia = xlrd.open_workbook(file_contents = libro_dia)

When libro_dia is not valid, it raises the following error:

XLRDError: Unsupported format, or corrupt file: Expected BOF record; found '<!DOCTYP'

I whant to handle this error, so I write:

try:
    libro_dia = xlrd.open_workbook(file_contents = libro_dia)
except XLRDError:
    no_termina = False

But it raises the following error:

NameError: name 'XLRDError' is not defined

What's going on?

Answer 1

You don't have XLRDError imported. I'm not familiar with xlrd, but something like:

from xlrd import XLRDError

might work. Alternatively, qualify your Error when handling it:

try:
    libro_dia = xlrd.open_workbook(file_contents = libro_dia)
except xlrd.XLRDError: #<-- Qualified error here
    no_termina = False

The above is assuming you have the following import:

import xlrd

---

In response to your comment:

There are several ways to use imports in python. If you import by using import xlrd, then you will have to qualify every object in that module as xlrd.SomeObject. An alternative way is by using the form from xlrd import *, which would allow you to reference the XLRD error without its' module namespace. This is lazy and a bad idea though, as it can lead to namespace clashes. If you would like to reference the error without qualifying it, the correct way to do it would be from xlrd import XLRDError, which would allow you to say except XLRDError. Read more about Python Modules

Answer 2

XLRDError is a custom exception and must be imported to your namespace just like any other object.

Edit: As Burhan Khalid has noted, you could just modify the except block to except xlrd.XLRDError if you already have import xlrd in your module.