Xpath test for ancestor attribute not equal string

Question

I'm trying to test if an attribute on an ancestor of an element not equal a string.

Here is my XML...

<aaa att="xyz">
<bbb>
<ccc/>
</bbb>
</aaa>
<aaa att="mno">
<bbb>
<ccc/>
</bbb>
</aaa>

If I'm acting on element ccc, I'm trying to test that its grandparent aaa @att doesn't equal "xyz".

I currently have this...

ancestor::aaa[not(contains(@att, 'xyz'))]

Thanks!

Answer 1

Assuming that by saying an ancestor of an element you're referring to an element with child elements, this XPath expression should do:

//*[*/ccc][@att != 'xyz']

It selects

1. all nodes
2. that have at least one <ccc> grandchild node
3. and that have an att attribute whose value is not xyz.

Update: Restricted test to grandparents of <ccc>.

Update 2: Adapted to your revised question:

//ccc[../parent::aaa/@att != 'xyz']

Selects

1. all <ccc> elements
2. that have a grandparent <aaa> with its attribute att set to a value that is not xyz