Question

我有一个包含许多元素的xml文件，我希望根据它们的索引删除某些元素。

示例XML：

<songs>
   <song>
      <title>A</title>
      <artist>AA</artist>
   </song>
</songs>

我到目前为止的PHP代码：

<?php

$index = $_GET['song'];

$doc = new DOMDocument();
$doc->load("songs.xml");
$songs = $doc->getElementsByTagName("song");

foreach($songs as $song) {
    if(in_array($song[$index], $songs)){
        unset($song);
    }
}
$doc->save("songlist.xml");

?>

但是我从这段代码中得到了这个错误：

Fatal error: Cannot use object of type DOMElement as array

本期内有任何帮助，谢谢。

Answer 1

如果您打算删除整个<song>元素。使用->removeChild()：

$songs = $doc->getElementsByTagName('song');
$hated_artists = array('AA', 'BB', 'CC');
foreach($songs as $song) {
    $artist = $song->getElementsByTagName('artist')->item(0)->nodeValue;
    if(in_array($artist, $hated_artists)) { // if this song is sang by one of your hated artists
        $song->parentNode->removeChild($song); // remove this song
    }
}

Sample Usage

如果您只想要一个简单的条件，请使用所需的密钥删除，然后只需使用foreach密钥即可。例如：

$keys_to_be_removed = array(14, 18);
foreach($songs as $key => $song) {
    if(in_array($key, $keys_to_be_removed)) {
        $song->parentNode->removeChild($song);
    }
}

或者只是在没有foreach循环的情况下明确使用索引来删除：

// starts at index zero
$first_song = $doc->getElementsByTagName('song')->item(0);
$songs = $doc->documentElement;
$songs->removeChild($first_song);

Answer 2

$songs = $doc->getElementsByTagName('song');

$songs.item(1).parentNode.removeChild($songs.item(1));
$songs.item(7).parentNode.removeChild($songs.item(7));
$songs.item(12).parentNode.removeChild($songs.item(12));

等...

Answer 3

XPath可以按索引/位置选择节点（以1开头）。它将始终返回可与foreach遍历的节点列表。如果索引不存在，列表将为空。要从DOM中删除节点，必须将其从父节点中删除。

$xml = <<<'XML'
<songs>
   <song>
      <title>A</title>
      <artist>AA</artist>
   </song>
</songs>
XML;

$index = 1; // (int)$_GET['song'];

$doc = new DOMDocument();
$doc->loadXml($xml);
$xpath = new DOMXPath($doc);

foreach ($xpath->evaluate('//song['.$index.']') as $song) {
  $song->parentNode->removeChild($song);
}

echo $doc->saveXml();

输出：

<?xml version="1.0"?>
<songs>

</songs>

根据索引删除xml元素节点

3 个答案: