How to Add an Attribute to All XML Tags Using Regex or PHP XML Extensions?

Regexp to Add Attribute in Any XML Tags

Question:

How can you use preg_replace to add a specific attribute to all XML tags in a well-formed XML document stored as a string variable? For instance, you want to modify the following XML:

<tag1>
<tag2> some text </tag2>
</tag1>

to:

<tag1 attr="myAttr">
<tag2 attr="myAttr"> some text </tag2>
</tag1>

Answer:

While it's tempting to use regular expressions for this task, it's not advisable. XML is not a regular language, and attempting to use regexes on it can lead to unexpected results. Instead, we recommend using the XML extensions of PHP:

<code class="php">$xml = new SimpleXml(file_get_contents($xmlFile));

function process_recursive($xmlNode)
{
    $xmlNode->addAttribute('attr', 'myAttr');

    foreach ($xmlNode->children() as $childNode)
    {
        process_recursive($childNode);
    }
}

process_recursive($xml);

echo $xml->asXML();</code>

This method ensures that all XML tags are properly modified, avoiding the potential pitfalls of using regular expressions on XML.

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