使用PHP从XML中删除空标记

Question

题

如何在PHP中删除空的xml标记？

例:

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

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

XML结果:

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

我想要的是!

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

没有像"tag3"这样的空标签的XML

谢谢!

Answer 1

您可以将XPath与谓词 not(node())一起使用,以选择所有没有子节点的元素.

<?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();

版画

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

Answer 2

这以递归方式工作并删除以下节点:

• 仅包含空格
• 没有属性
• 没有孩子的笔记

// 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);
    }
}

Answer 3

$dom = new DOMDocument;

$dom->loadXML($xml);

$elements = $dom->getElementsByTagName('*');

foreach($elements as $element) {

   if ( ! $element->hasChildNodes() OR $element->nodeValue == '') {
       $element->parentNode->removeChild($element);
   }

} 

echo $dom->saveXML();

CodePad.