[Tutor] pyXML DOM 2.0 Traversal and filters

[Levy Lazarre]

Hi Fellow Listers,

Given the following sample file ('appliances.xml'), I
am trying to write a TreeWalker that would print out
the element
nodes, while a filter would prevent the nodes with a
status of "broken" from displaying.

<?xml version="1.0"?>
<appliances>
    <clock status = "working">cuckoo</clock>
    <television status = "broken">black and
white</television>
</appliances>

I am getting some exceptions, making me think that I
am calling the filter the wrong way or I am missing
something.
Can somebody please point me to the right direction?
Here is the sample code: 

########### SNIP ####################
from xml.dom.ext.reader import Sax2
from xml.dom.NodeFilter import NodeFilter

# Rejects element nodes with a "status"  attribute of
"broken":
def filterbroken(thisNode):
    if (thisNode.nodeType == thisNode.ELEMENT_NODE and
thisNode.getAttribute("status") == "broken"):
            return NodeFilter.FILTER_REJECT

    return NodeFilter.FILTER_ACCEPT     # else, accept
the node

# create Reader object
reader = Sax2.Reader()

input_file = file("appliances.xml")          
doc = reader.fromStream(input_file)          # Parse
the input file, get a DOM tree.

walker = doc.createTreeWalker(doc.documentElement,
NodeFilter.SHOW_ALL, filterbroken, 0)

while 1:
 	print walker.currentNode.nodeName, ': ',
walker.currentNode.nodeValue  
 	next = walker.nextNode()
 	if next is None: break


input_file.close()
reader.releaseNode(doc)
##########################################

Here are the exceptions I am getting:
>>> appliances :  None
Traceback (most recent call last):
  File
"C:\Python22\Lib\site-packages\Pythonwin\pywin\framework\scriptutils.py",
line 301, in RunScript
    exec codeObject in __main__.__dict__
  File "C:\temp\Listing4.14.py", line 21, in ?
    next = walker.nextNode()
  File
"C:\Python22\Lib\site-packages\_xmlplus\dom\TreeWalker.py",
line 128, in nextNode
    next_node = self.__advance()
  File
"C:\Python22\Lib\site-packages\_xmlplus\dom\TreeWalker.py",
line 141, in __advance
    if self.firstChild():
  File
"C:\Python22\Lib\site-packages\_xmlplus\dom\TreeWalker.py",
line 85, in firstChild
    if
self.__checkFilter(self.__dict__['__currentNode']) !=
NodeFilter.FILTER_REJECT:
  File
"C:\Python22\Lib\site-packages\_xmlplus\dom\TreeWalker.py",
line 168, in __checkFilter
    return self.__dict__['__filter'].acceptNode(node)
AttributeError: 'function' object has no attribute
'acceptNode'

There are no exceptions when the filter is replaced by
None in the 'walker ='  statement.

Thanks in advance,
Levy Lazarre
Information Systems
Winter Haven Hospital
llazarre@yahoo.com


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