TypeError: 'in <string>' requires string as left operand, not Element

Roy Smith roy at panix.com
Mon Dec 10 02:08:39 CET 2012


In article <8c78344a-8019-450a-bfdf-13508bf75292 at googlegroups.com>,
 Victor Hooi <victorhooi at gmail.com> wrote:

> Hi,
> 
> I'm getting a strange error when I try to run the following:
> 
>     for root, dirs, files in os.walk('./'):
>         for file in files:
>             if file.startswith('ml') and file.endswith('.xml') and 'entity' 
>             not in file:
>                 print(root)
>                 print(file)
>                 with open(os.path.join(root, file), 'r') as f:
>                     print(f.name)
>                     try:
>                         tree = etree.parse(f)
>                         root = tree.getroot()
>                         print(f.name)
>                         print(root.tag)
>                     except xml.parsers.expat.ExpatError as e:
>                         print('Unable to parse file {0} - {1}'.format(f.name, 
>                         e.message))
> 
> The error is:
> 
> Traceback (most recent call last):
>   File "foo.py", line 275, in <module>
>     marketlink_configfiles()
>   File "foo.py", line 83, in bar
>     with open(os.path.join(root, file), 'r') as f:
>   File "C:\Python27\lib\ntpath.py", line 97, in join
>     if path[-1] in "/\\":
> TypeError: 'in <string>' requires string as left operand, not Element
> 
> Cheers,
> Victor

The first thing I would do is try to figure out if it's happening in the 
join() or the open().  Try refactoring this as:

>                 temp = os.path.join(root, file)
>                 with open(temp, 'r') as f:

and see which line generates the exception.  I'm guessing it's the 
join(), but it helps to make sure (so you don't go down some rabbit 
hole).  Next, I would try to construct a minimal test case.  Keep 
hacking away code until you get down to the smallest thing which is 
produce the problem.  I'm guessing something like:

>     for root, dirs, files in os.walk('./'):
>         for file in files:
>             os.path.join(root, file)

might do it.  Hopefully that will narrow things down a bit.



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