How to filter with XPath on all elements without a specific attribute

Question

My XPath is a little bit rusty... Let's say I have this simple XML file:

<?xml version="1.0" encoding="utf-8" ?>
<States xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<States>
<StateProvince name="ALABAMA" abbrev="AL" />
....
<StateProvince name="AMERICAN SAMOA" abbrev="AS" territory="true"  />
</States>
</States>

I would like to run a simple XPath query to parse out all of the true states (so don't pull in states where territory = true). I tried \StateProvince[@territory!='true'] but I got zero. Other variations seem to be failing. This seems like it should be simple, but not finding what I want.

Any help appreciated.

Solution 1

One XPath expression that selects the wanted elements:

        /*/States/StateProvince[not(@territory='true')]

Do note that one must avoid the // abbreviation whenever possible as it causes the whole document (subtree rooted at the context node) to be scanned.

The above XPath expression avoids the use of the // abbreviation by taking into account the structure of the originally-provided XML document.

Only if the structure of the XML document is completely unknown (and the XPath expression is intended to be used accross many XML documents with unknown structure) should the use of the // abbreviation be considered.

Solution 2

You are very close:

//StateProvince[not(@territory) or @territory != 'true']

Should get you the result you want.

Solution 3

This should work:

//StateProvince[not(@territory='true')]

Comments

[lyngbym]

I agree this is also good practice, but in my case it is just a very small xml that will be cached after it is loaded.

[Dimitre Novatchev]

@lyngbym Even for small XML documents using '//' may terribly affect performance (if these XPath expressions are issued frequently). Also, if one gets used to '//' with small docs, then the chances are great (s)he will forget and use it with bigger documents and thus create a performance disaster. After all, who decides how small is "small" and where it stops to be "small" ?