Xpath query to select node when attribute does not exist?

Question

I want to select nodes for which a specific attribute does not exist. I've tried the Not() function, but it doesn't work. Is there a way for this?

Example: The following Xpath query:

group/msg[not(@owner)]

Should retrieve the first node but not the 2nd one. However, both SketchPath (tool to test Xpath queries) and my C# code consider that the 2 nodes are ok.

<group>
    <msg id="EVENTDATA_CCFLOADED_XMLCONTEXT"  numericId="14026"  translate="False"  topicId="302"  status="translated" >
        <text>Context</text>
        <comment></comment>
    </msg>
    <msg id="EVENTDATA_CCFLOADED_XMLCONTEXT_HELP"  numericId="14027"  translate="False"  topicId="302"  status="translated"  owner="EVENTDATA_CCFLOADED_XMLCONTEXT" >
        <text>Provides the new data displayed in the Object.</text>
        <comment></comment>
    </msg>
</group>

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In fact the Not() function works correctly, it's just that I had other conditions and parentheses weren't set correctly. errare humanum est.

Answer 1

In some old and not very standard XPATH engine I had to use string-length(@attr)=0 for the same reason.

Answer 2

Works for me when testing with XPath Explorer (based on Jaxen library).
So I guess it is indeed depending on the XPath implementation.