XPath - Find elements by attribute namespace

Question

I'm trying to use XPath to find all elements that have an element in a given namespace.

For example, in the following document I want to find the foo:bar and doodah elements

<?xml version="1.0" encoding="UTF-8"?>
<root xmlns:foo="http://foo.example.com"&gt;
  <foo:bar quux="value">Content</foo:bar>
  <widget>Content</widget>
  <doodah foo:quux="value">Content</doodah>
</root>

I know I can use the following XPath expression to load all attributes from a given namespace

"//@*[namespace-uri()='http://foo.example.com']"

However:

• This doesn't give me the elements, just the attributes and
• where elements contain multiple attributes from that namespace, this XPath will return a result per-attribute rather than per-element

Is it possible to get what I want, or do I just have to gather the attributes and calculate the unique set of elements they correspond to ?

EDIT: I was given the following answer by Dimitre Novatchev. I didn't realise that you could nest predicates inside predicates like this:

"//*[@*[namespace-uri()='http://foo.example.com']]"

Specifically this says "Any element that has any attribute that has namespace-uri = '...'"

Answer 1

Not sure if this is what you mean, but by only deleting 1 char in your XPath you get all elements in a certain namespace:

//*[namespace-uri()='http://foo.example.com']

Answer 2

You could try

//*[namespace-uri()='http://foo.example.com' or @*[namespace-uri()='http://foo.example.com']]

It will give you element foo:bar and element doodah (if you change tal:quux to foo:quux in your XML-data):

<?xml version="1.0" encoding="UTF-8"?>
<root xmlns:foo="http://foo.example.com" xmlns:tal="xxx">
  <foo:bar quux="value">Content</foo:bar>
  <widget>Content</widget>
  <doodah foo:quux="value">Content</doodah>
</root>

is that what you want?

EDIT: Thanks for spotting the attribute mistake, corrected now.

Answer 3

Your XPath expression is almost perfect. Instead of asking for attributes "@" ask for elements "" and it should work:

"//*[namespace-uri()='http://foo.example.com']"

Answer 4

Use:

  //*[namespace-uri()='yourNamespaceURI-here'
     or
      @*[namespace-uri()='yourNamespaceURI-here']
     ]

the predicate two conditions are or-ed with the XPath or operator.

The XPath expression thus selects any element that either:

• belongs to the specified namespace

or

• has attributes that belong to the specified namespace