XPath
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External
- https://www.baeldung.com/linux/evaluate-xpath
- https://www.w3schools.com/xml/xpath_intro.asp
- https://www.w3schools.com/xml/xpath_syntax.asp
Internal
Overview
XPath is a specification language that allows specifying parts of an XML structure. It is part of XSL. An XPath expression can be thought as an address of a part of an XML document.
TODO: https://docs.oracle.com/javase/tutorial/jaxp/xslt/xpath.html
Command Line Tooling
Java Support
Syntax
Example
<books>
<book id="1" category="linux">
<title lang="en">Linux Device Drivers</title>
<year>2003</year>
<author>Jonathan Corbet</author>
<author>Alessandro Rubini</author>
</book>
<book id="2" category="linux">
<title lang="en">Understanding the Linux Kernel</title>
<year>2005</year>
<author>Daniel P. Bovet</author>
<author>Marco Cesati</author>
</book>
<book id="3" category="novel">
<title lang="en">A Game of Thrones</title>
<year>2013</year>
<author>George R. R. Martin</author>
</book>
<book id="4" category="novel">
<title lang="fr">The Little Prince</title>
<year>1990</year>
<author>Antoine de Saint-Exupéry</author>
</book>
</books>
Node Selection
XPath uses path expressions to select nodes in an XML document. The node is selected by following a path (or steps):
/
Select from the root node.
/books/book/title
xml sel -t -v "/books/book/title" ./books.xml
returns:
Linux Device Drivers Understanding the Linux Kernel A Game of Thrones The Little Prince
nodename
Select the node (or nodes) with the given nodename. If multiple nodes with the same node match, they're all selected.
Queries
Full Path Queries
/level-1-element-name/level-2-element-name/...
Recursive Queries
Recursive query based on element name:
//element-name<selector>
Element Selection
element-name[@attribute-name='value']
element-name[sub-element-expression]