One of the more sophisticated mechanisms available in XPath is the "filter." Filters are logical expressions that nodes must satisfy in order to be included in a result set. A filter is added to an XPath expression by placing it in brackets to the right of a path term. Filters typically employ logical operators acting upon an element's children. For instance, the expression
account-status[past-due > 30]
checks to see whether the element "account-status" has a child "past-due" that is greater than thirty. So, if we have a document with the nodeset
we can obtain the account number of all account more than thirty days past due with the expression
The expression "text()" is used to extract the content of the preceding step in the path—in this case, the "account-number" element. It's useful whenever one needs to extract the content of an element rather than the element as a whole. Executing this expression provides the following result:
Note: The sample code in this tutorial makes use of the Tectonic programming language
(featured in the Delve SOA Fast-Prototyping Toolkit)
Not sure exactly what the heck XML is? Get started with this
excellent wikipedia article:
> Click Here!
