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PHP XML Handling: XPath Query and Application Examples

gitbox 2025-06-30

Introduction

XPath is a powerful tool for manipulating XML documents in PHP, enabling developers to easily navigate and select elements within the XML structure. This article presents several examples of how to use XPath in PHP for XML document querying.

XML and XPath Overview

XML (Extensible Markup Language) is a flexible markup language used for storing and transmitting data. XPath is a language used for locating nodes in XML documents through path expressions that describe the location of the nodes.

Using XPath Selectors

In PHP, we can use the DOM extension and the DOMXPath class to operate on XML documents with XPath expressions. Here is an example XML document:


<bookstore>
  <book category="cooking">
    <title lang="en">Everyday Italian</title>
    <author>Giada De Laurentiis</author>
    <year>2005</year>
    <price>30.00</price>
  </book>
  <book category="children">
    <title lang="en">Harry Potter</title>
    <author>J.K. Rowling</author>
    <year>2003</year>
    <price>29.99</price>
  </book>
  <book category="web">
    <title lang="en">PHP Cookbook</title>
    <author>David Sklar</author>
    <year>2014</year>
    <price>40.00</price>
  </book>
</bookstore>

Selecting All Book Nodes

First, we can use XPath to select all the book nodes in the XML. Here’s the PHP code for this:


$xml = new DOMDocument();
$xml->load('books.xml');
$xpath = new DOMXPath($xml);
$books = $xpath->query('//book');
foreach ($books as $book) {
    // Process each book
}

In the above code, the XPath expression “//book” selects all “book” nodes in the XML document. We can then use a `foreach` loop to iterate over the selected nodes and process them.

Selecting Book Nodes with Specific Attributes

Next, we can filter book nodes based on specific attribute values. For example, selecting all books with a category of “cooking”:


$xpath = new DOMXPath($xml);
$books = $xpath->query('//book[@category="cooking"]');
foreach ($books as $book) {
    // Process books with category "cooking"
}

The XPath expression “//book[@category='cooking']” selects all book nodes where the category attribute is equal to “cooking”.

Selecting Book Nodes with Specific Child Nodes

We can also filter nodes by the presence of specific child elements. For example, selecting books that have a “title” child node:


$xpath = new DOMXPath($xml);
$books = $xpath->query('//book[title]');
foreach ($books as $book) {
    // Process books with a "title" child node
}

The XPath expression “//book[title]” selects all book nodes that contain at least one “title” child node.

Conclusion

XPath is an efficient and powerful way to manipulate XML documents in PHP. It allows developers to quickly locate and filter elements within XML documents based on various conditions. This article has introduced several basic XPath query techniques and shown practical examples of how to use them in PHP. We hope it helps you better understand XPath's applications in PHP XML handling.

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