Remove empty tags from a XML with PHP

Question

How can I remove empty xml tags in PHP?

Example:

 $value1 = "2";
 $value2 = "4";
 $value3 = "";

 xml = '<parentnode>
        <tag1> ' .$value1. '</tag1>
        <tag2> ' .$value2. '</tag2>
        <tag3> ' .$value3. '</tag3>
       </parentnode>';

XML Result:

<parentnode>
    <tag1>2</tag1>
    <tag2>4</tag2>
    <tag3></tag3> // <- Empty tag
</parentnode>

What I want!

    <parentnode>
            <tag1>2</tag1>
            <tag2>4</tag2> 
    </parentnode>

The XML without the empty tags like "tag3"

Thanks!

Solution 1:

You can use XPath with the predicate not(node()) to select all elements that do not have child nodes.

<?php
$doc = new DOMDocument;
$doc->preserveWhiteSpace = false;
$doc->loadxml('<parentnode>
    <tag1>2</tag1>
    <tag2>4</tag2>
    <tag3></tag3>
    <tag2>4</tag2>
    <tag3></tag3>
    <tag2>4</tag2>
    <tag3></tag3>
</parentnode>');

$xpath = new DOMXPath($doc);

foreach( $xpath->query('//*[not(node())]') as $node ) {
    $node->parentNode->removeChild($node);
}

$doc->formatOutput = true;
echo $doc->savexml();

prints

<?xml version="1.0"?>
<parentnode>
  <tag1>2</tag1>
  <tag2>4</tag2>
  <tag2>4</tag2>
  <tag2>4</tag2>
</parentnode>

Solution 2:

This works recursively and removes nodes that:

• contain only spaces
• do not have attributes
• do not have child notes

// not(*) does not have children elements
// not(@*) does not have attributes
// text()[normalize-space()] nodes that include whitespace text
while (($node_list = $xpath->query('//*[not(*) and not(@*) and not(text()[normalize-space()])]')) && $node_list->length) {
    foreach ($node_list as $node) {
        $node->parentNode->removeChild($node);
    }
}