How to find elements by attribute namespace in XPath

21
votes

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">
  <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.
  • Where elements contain multiple attributes from that namespace, this selector will return a result per-attribute rather than per-element

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

4
xmlxpathnamespaces
Did you forgot to add a namespace for doodah? Because I don't see how it can be selected through a namespace. – potyl
If the clarifications weren't clear, I used the wrong namespace in my original example. My mistake. – Gareth
Thanks for this post, it really helped. To sum up: - To get elements with attributes from a given namespace: //*[@*[namespace-uri()='http://foo.example.com']] - To get attributes from a given namespace: //@*[namespace-uri()='http://foo.example.com'] – Lance Pollard

4 Answers

27
votes

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.
  • has attributes that belong to the specified namespace.
4
votes

I'm not sure if this is what you mean, but by only deleting one char in your XPath you get all elements in a certain namespace:

//*[namespace-uri()='http://foo.example.com']
1
votes

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?

0
votes

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

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