xpath expression from xml with namespace prefix

17
votes

I could not get the following xpath expression to work when the xml path namespace prefix set.

/bk:BookStore/bk:Books/bk:Book[text()='Time Machine']

XML is:

<BookStore xmlns:bk="http://www.bookstore.com/book#">
  <bk:Books>
    <bk:Book id="1">Time Machine></bk:Book>
  </bk:Books>
</bk:BookStore>
2
xmlxpathnamespacesxml-namespacesprefix
Post the code that executes the XPath query. – Tomalak
You need to pass the prefix/namespace-URI binding to your XPath engine. Why? Because prefixes are not important for name test, but namespace URI are. So a:node could select b:node as long as a and b prefixes are binding to the same namespace URI. – user357812

2 Answers

36
votes

Or even better (and more portable), without the unnecessary prefix:

/*/*[local-name()='Books'] ... and so on

The function local-name ignores any prefix, which, as correctly stated by commenters, can vary.

18
votes

Without more information about the host language (in which you attempt to evaluate XPath expressions) it is not possible to provide an useful recommendation.

Generally, one needs to "register" a namespace with a namespace manager and this also associates a prefix to the registered namespace. Then, using this NamespaceManager object as an argument to the XPath-evaluation method, one can specify as argument to this method an XPath expression that contains names prefixed by that particular prefix.

Workarounds:

/*/*[name()='bk:Books']/*[name()='bk:Book' and text()='Time Machine']