On Wed, 2007-02-28 at 12:43 -0500, Stefan Jeglinski wrote:
> There's likely a better list for this, but I've been spending
> most/all of my time at xmlsoft.org. I'm teaching myself xml, and I
> must be braindead - I just can't get past this one.
>
> I've got xmllib2 compiled, and can compile and run a variety of the
> test code examples. I'm trying to get my head around xpath. Here is
> my toy xml file:
>
> <?xml version="1.0" standalone="yes"?>
> <!DOCTYPE myroot [
> <!ELEMENT myroot (myelement+)>
> <!ELEMENT myelement (x,y)>
> <!ATTLIST myelement type (a | b) #REQUIRED>
> <!ELEMENT x (#PCDATA)>
> <!ELEMENT y (#PCDATA)>
> ]>
> <myroot>
> <myelement type="a">
> <x>1a</x>
> <y>2a</y>
> </myelement>
> <myelement type="b">
> <x>1b</x>
> <y>2b</y>
> </myelement>
> </myroot>
>
>
> Using the xpath1.c sample code, I can successfully find element
> nodes, but I can't "subselect" based on type. for example, this xpath:
>
> /myroot/myelement/@type
>
> returns 2 type nodes (as expected?), but no matter what syntax I've
> tried (I've googled, looked in books), I cannot select type a or b by
> itself, for example with umpteen variants of something along these
> lines:
>
> /myroot/myelement/@type[.='a']
>
> I suspect I'm barking up the wrong tree (not to pun). Am I misusing
> xpath, probably on several levels? Have I missed a really dumb step
> in building the xml file to begin with? Other? Ultimately I want to
> be able to specify one element alone in the xml document using xpath
> - it's not so much that any final implementation will work like
> this... I just want to understand it.
I think what you want is this: /myroot/[EMAIL PROTECTED]"a"]
here is a simple python program to play with:
#!/usr/bin/env python
import libxml2
str_doc = '''<?xml version="1.0" standalone="yes"?>
<myroot>
<myelement type="a">
<x>1a</x>
<y>2a</y>
</myelement>
<myelement type="b">
<x>1b</x>
<y>2b</y>
</myelement>
</myroot>
'''
xpath_expr = '/myroot/[EMAIL PROTECTED]"a"]'
doc = libxml2.parseDoc(str_doc.strip())
root_node = doc.getRootElement()
context = doc.xpathNewContext()
context.setContextNode(root_node)
elements = context.xpathEval(xpath_expr)
print "'%s' expression returned %s" % (xpath_expr, elements)
--
John Dennis <[EMAIL PROTECTED]>
Learn. Network. Experience open source.
Red Hat Summit San Diego | May 9-11, 2007
Learn more: http://www.redhat.com/promo/summit/2007
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