XPath
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):
nodename
Select the node (or nodes) with the given nodename. If multiple nodes with the same node match, they're all selected.
xml sel -t -v "/books/book/title" ./books.xml
/
Select from the root node.
xml sel -t -v "/books/book/title" ./books.xml
//
Selects nodes in the document from the current node that match the selection no matter where they are/
xml sel -t -v "//title" ./books.xml
.
Selects the current node
..
Selects the parent of the current node
@
Selects attributes.
Predicates
Predicates are used to find a specific node or a node that contains a specific value. Predicates are always embedded in square brackets.
Element Selection
element-name[@attribute-name='value']
element-name[sub-element-expression]