[XML-SIG] help - attributes namespace - is this a bug in PyXML
and at doxdesk.com
Tue Aug 17 03:56:11 CEST 2004
Mike Brown <mike at skew.org> wrote:
> I'm not very experienced with using minidom but that's surprising to me.
Probably because Ajay isn't using minidom :-)
> from xml.dom.minidom import parseString
> inputString = '<appel:RULE appel:empty="" appel:full="hi"/>'
> doc = parseString(inputString)
> I would've expected None
'' is correct in this case. getAttribute returns an empty string if no
attribute is found as per DOM Level 1 spec. It is getAttributeNode that
returns None (null) when the attribute is not found.
> it seems weird that '' and u'' mean different things
They don't. Python binds the DOMString type to strings in general, so
both unicode and narrow strings can be used. (Though it is usually best
to use unicode, and definitely a bad idea to be putting non-ASCII
characters in narrow binary strings.) It just happens that minidom
returns a narrow empty string for attribute-not-found; it could just as
easily be u''.
> Therefore you should not be using
> getAttribute()/getAttributeNS() to test for existence of an attribute.
Indeed. This can be useful when an attribute value should act as if
defaulting to the empty string.
> What you should be doing is using hasAttribute or hasAttributeNS.
Yep. Alternatively getAttributeNode can also do the job.
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