为什么getElementById在这种情况下不起作用？ [英] Why getElementById doesn't work in this case?
问题描述
我有一些PHP代码。
PHP：
$Implementation = new DOMImplementation();
$Document = $Implementation->createDocument( NULL, NULL, $Implementation->createDocumentType( 'html' ) );
$Document->encoding = 'utf-8';
$Document->loadXML( $main_html[ 'main' ] ); // load main.html
$Document->xinclude();
$Fragment = $Document->createDocumentFragment();
$Fragment->appendXML( $main_html[ 'page' ] ); // load page.html
$Document->getElementById( 'content' )->appendChild( $Fragment );
...
除了最后一行，一切都很顺利，出现错误：
Everything works well except last line, appears error:
PHP Fatal error: Call to a member function appendChild() on a non-object
似乎 getElementById（）方法不适用于 $ Document 。
It seems getElementById() method doesn't work for $Document.
查看HTML。
HTML（main.html）：
HTML (main.html):
...
</head>
<body xmlns:xi="http://www.w3.org/2001/XInclude">
<xi:include href="wrapper.html" />
</body>
</html>
HTML（wrapper.html）：
HTML (wrapper.html):
<section
id="wrapper"
xmlns:xi="http://www.w3.org/2001/XInclude">
<xi:include href="header.html" />
<xi:include href="nav.html" />
<xi:include href="content.html" />
<xi:include href="aside.html" />
<xi:include href="footer.html" />
</section>
HTML（content.html）：
HTML (content.html):
<section id="content" />
我添加了 $ Document-> validateOnParse = TRUE; before $ Document-> loadXML（$ main_html ['main']）; 并在没有XInclude的情况下测试，但没有工作。
I added $Document->validateOnParse = TRUE; before $Document->loadXML( $main_html[ 'main' ] ); and tested without XInclude, but doesn`t work.
最后，我发现解决方案，坏行替换为：
Finally I found the solution, bad line replace with:
$Document->getElementsByTagName( 'section' )->item( 1 )->appendChild( $Fragment );
getElementsByTagName（）方法适用于 $ Document 但不满足我。我错过了什么吗？
getElementsByTagName() method works for $Document but doesn't satisfy me. Did I missed something?
推荐答案
你必须传递一个定义 id 属性。否则，您不能使用 getElementById 。
You have to pass a DTD which defines the id attribute. Otherwise, you cannot use getElementById.
有关详细信息，请参阅：
For more information, see:
- http：// nl。 php.net/manual/en/domimplementation.createdocumenttype.php
- http://www.php.net/manual/en/domdocument.getelementbyid.php
- http://nl.php.net/manual/en/domimplementation.createdocumenttype.php
- http://www.php.net/manual/en/domdocument.getelementbyid.php
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