php:dom从另一个dom的根节点替换节点

Question

我需要从其他文档的整个节点更新节点:

原始XML:

<a>
<b>Bat</b>
</a>

我想要的输出:

<a>
<b>bi</b>
</a>

第一次尝试:替换为documentfragment

    $original = "<a>
    <b>Bat</b>
    </a>";
    $replace = "<b>Bi</b>";

    $dom = new DOMDocument('1.0', 'utf-8');
    $dom->loadXML($original);

    $xpath = new DOMXpath($dom);
    $b = $xpath->query('//b')->item(0);

    $fragment = $dom->createDocumentFragment();
    $fragment->appendXML($replace);

    $dom->replaceChild($fragment, $b);

    echo $dom->saveXML();

错误:

致命错误:/home/zital/scripts/php/dom.php:17中未捕获的异常'DOMException',消息'未找到错误'堆栈跟踪:

0 /home/zital/scripts/php/dom.php(17):DOMNode-> replaceChild(Object(DOMDocumentFragment),Object(DOMElement))

在第17行的/home/zital/scripts/php/dom.php中抛出1 {main}

第二次尝试:通过导入节点替换

$original = "<a>
        <b>Bat</b>
</a>";
$replace = "<b>Bi</b>";

$dom = new DOMDocument('1.0', 'utf-8');
$dom->loadXML($original);

$xpath = new DOMXpath($dom);
$b = $xpath->query('//b')->item(0);

$dom2 = new DOMDocument('1.0', 'utf-8');
$dom2->loadXML($replace);

$replace = $dom2->documentElement;
$replace = $dom->importNode($replace, true);

$dom->replaceChild($replace, $b);

echo $dom->saveXML();

错误:

致命错误:/home/zital/scripts/php/dom.php:42中未捕获的异常'DOMException',消息'未找到错误'堆栈跟踪:

0 /home/zital/scripts/php/dom.php(42):DOMNode-> replaceChild(Object(DOMElement),Object(DOMElement))

在第42行/home/zital/scripts/php/dom.php中抛出1 {main}

Answer 1

您没有再采取任何步骤来获取 documentElement

$dom->documentElement->replaceChild($replace, $b);

结果将是

<?xml version="1.0"?>
<a><b>Bi</b></a>

更新：

根据相当正确的 Yoshi 评论，最好这样写

$b->parentNode->replaceChild($replace, $b);