[lxml-dev] Help with an error message

[James William Pye]

Stefan Behnel <stefan_ml <at> behnel.de> writes:
> Konstantin Ryabitsev wrote:
> > Traceback (most recent call last):
> >   File "foo.py", line 6, in <module>
> >     elt = Element('foo').text = unistr
> >   File "etree.pyx", line 741, in etree._Element.text.__set__
> >   File "apihelpers.pxi", line 344, in etree._setNodeText
> >   File "apihelpers.pxi", line 648, in etree._utf8
> > AssertionError: All strings must be XML compatible, either Unicode or ASCII
> > 
> > Can someone suggest the best way to deal with this?
> 
> My first question is: why do you need a '\x00' here? If you want to pass
> binary data in XML, the best way is to use a safe encoding such as uuencode or
> whatever. That should be part of your XML language spec/schema/...


I just ran into this myself. In my case, having the NULL was not desired, rather
I wanted to see a raw '\x00' to appear in the string(ie, the literal backslash
sequence, *not* the NULL character).

It would be nice if lxml would be more explicit about the problem:

 raise ValueError("NULL characters are not allowed in XML strings")

That is: How I am supposed to derive that a NULL character was causing that
AssertionError from the given string? (It wasn't until I found this message that
I understood what I was doing wrong)