XML Handling

Introduction

Before JSON became the default, XML was the standard format for structured data on the web, and it is still very much alive today in legacy APIs, RSS/Atom feeds, and configuration files for various tools and services. Sooner or later, a PHP project will hand you a chunk of XML to parse.

This lesson covers PHP's SimpleXML extension, the easiest way to read XML data, and briefly introduces DOMDocument for when you need finer control.

What Is XML and Where Is It Still Used?

XML (Extensible Markup Language) represents structured data using nested, named tags, similar in spirit to HTML but designed for data rather than display. A piece of data is wrapped in an opening and closing tag, and tags can carry attributes as well as nested child elements.

<user id="42">
    <name>Jane Doe</name>
    <email>jane@example.com</email>
</user>

Reading XML with SimpleXML

PHP's SimpleXML extension turns an XML string into an object you can navigate almost like a regular PHP object, using -> to move between elements. Use simplexml_load_string() when the XML is already in a PHP string.

<?php
$xmlString = '<user id="42">
    <name>Jane Doe</name>
    <email>jane@example.com</email>
</user>';

$user = simplexml_load_string($xmlString);

echo $user->name . "\n";
echo $user->email;

Jane Doe
jane@example.com

simplexml_load_string() returns a SimpleXMLElement object on success, or false if the XML could not be parsed.

Accessing Elements and Attributes

Child elements are accessed as properties (->name), and repeated child elements become an iterable collection. Attributes are accessed by treating the element like an array.

<?php
$xmlString = '<user id="42">
    <name>Jane Doe</name>
    <email>jane@example.com</email>
</user>';

$user = simplexml_load_string($xmlString);

// Attributes are accessed like array keys
echo "ID: " . $user["id"] . "\n";

// Elements are accessed like object properties
echo "Name: " . $user->name . "\n";

ID: 42
Name: Jane Doe

When an element repeats — like multiple <item> tags inside a <items> parent — SimpleXML lets you loop over them directly with foreach.

<?php
$xmlString = '<library>
    <book><title>PHP Basics</title></book>
    <book><title>Learning SQL</title></book>
</library>';

$library = simplexml_load_string($xmlString);

foreach ($library->book as $book) {
    echo $book->title . "\n";
}

PHP Basics
Learning SQL

Loading XML from a File

When the XML lives in a separate .xml file rather than a PHP string, use simplexml_load_file() instead, which reads the file directly.

<?php
$library = simplexml_load_file("catalog.xml");

if ($library === false) {
    echo "Failed to load or parse catalog.xml";
} else {
    foreach ($library->book as $book) {
        echo $book->title . "\n";
    }
}

PHP Basics
Learning SQL

DOMDocument: A More Powerful Alternative

SimpleXML is great for quickly reading data, but it has limits: it is read-heavy, and modifying or building complex XML documents with it can get awkward. For more demanding work — creating new XML documents, using XPath queries, or manipulating a document's structure — PHP's DOMDocument class offers a fuller, more powerful API.

<?php
$dom = new DOMDocument();
$dom->loadXML('<user id="42"><name>Jane Doe</name></user>');

$nameNode = $dom->getElementsByTagName("name")->item(0);
echo $nameNode->textContent;

Jane Doe

Example: Parsing an XML Snippet

Here is a complete, self-contained example: a small XML feed of articles, parsed and printed as a plain summary.

<?php
$feed = '<feed>
    <article id="1">
        <title>Getting Started with PHP</title>
        <author>Jane Doe</author>
    </article>
    <article id="2">
        <title>Understanding Arrays</title>
        <author>John Smith</author>
    </article>
</feed>';

$data = simplexml_load_string($feed);

if ($data === false) {
    echo "Could not parse feed.";
} else {
    foreach ($data->article as $article) {
        $id = $article["id"];
        echo "[$id] {$article->title} — by {$article->author}\n";
    }
}

[1] Getting Started with PHP — by Jane Doe
[2] Understanding Arrays — by John Smith

Common Mistakes

Best Practices

Frequently Asked Questions

Key Takeaways

Summary

XML may be older than JSON, but it remains a practical skill for PHP developers who work with legacy systems, feeds, or certain file formats. SimpleXML covers most everyday reading needs, while DOMDocument is there when you need more power.

Next, you will put both JSON and XML knowledge to work by learning how to consume external APIs directly from PHP.