XPath
You can use XPath to select nodes or sets of nodes in an XML document. Nodes are selected by following a path or steps.
XML Example
We will use this XML document in the following example.
<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
<book>
<title lang="eng">Harry Potter&</title>
<price>29.99</price>
</book>
<book>
<title lang="eng">Learning XML</title>
<price>39.95</price>
</book>
</bookstore>
Node Selection
You can use XPath to select nodes or sets of nodes in an XML document. Nodes are selected by following a path or steps.
Below are some of the most common path expressions.
| Expression | Description |
| nodename | Select all the children of this node |
| / | Select from the root node. |
| // | Select nodes in the document from the current node that matches the selection, regardless of their positions |
| . | Select the current node |
| .. | Select the parent node of the current node |
| @ | Select an attribute |
In the following table, we have listed some path expressions and the results of the expressions.
| Path Expression | Result |
| bookstore | Select all children of the bookstore element |
| /bookstore | Select the root element bookstore. If the path starts with a forward slash ( / ), then this path always represents an absolute path to an element |
| bookstore/book | Select all book elements that are children of the bookstore |
| //book | Select all book elements regardless of their position in the document |
| bookstore//book | Select all book elements that are children of bookstore elements, regardless of where they are located under the bookstore |
| //@lang | Select all attributes named lang |
Predicates
You can use predicates to find a specific node or a node containing a specified value.
The predicate is enclosed in square brackets.
In the following table, we have listed some path expressions with predicates and the results of the expressions.
| Path Expression | Result |
| /bookstore/book[1] | Select the first book element of the bookstore child elements |
| /bookstore/book[last()] | Select the last book element of the bookstore child elements |
| /bookstore/book[last()-1] | Select the second to the last book element of the bookstore child elements |
| /bookstore/book[position()] | Select the first two book elements of the bookstore child elements |
| //title[@lang] | Select all title elements that have an attribute named lang |
| //title[@lang='eng'] | Select all title elements that have a lang attribute with the value eng |
| /bookstore/book[price>35.00] | Select all book elements of the bookstore with the value of the price element greater than 35.00 |
| /bookstore/book[price>35.00]//title | Select all the title elements of the book element in the bookstore with the price element greater than 35.00 |
Selecting Unknown Nodes
The XPath wildcard can be used to select unknown XML elements.
| Wildcard | Description |
| * | Match any element node |
| @* | Match any attribute node |
| node() | Match any type of node |
In the following table, we have listed some path expressions and the results of these expressions.
| Path Expression | Result |
| /bookstore/* | Select all child elements of the bookstore element |
| //* | Select all elements in the document |
| //title[@*] | Select all title elements with attributes |
Select a Number of Paths
You can select several paths by using the "|" operator in a path expression.
In the following table, we have listed some path expressions and the results of these expressions.
| Path Expression | Result |
| //book/title | //book/price | Selects all title and price elements of the book element. |
| //title | //price | Select all title and price elements in the document |
| /bookstore/book/title | //price | Select all the title elements of the book element of the bookstore element and all the price elements in the document |