PHP文档模型：在组成的HTML文档中查找元素 [英] PHP document model: Finding an element in a composed HTML document
问题描述
我有一个使用DOM类组成HTML元素的库。我还想使用DOM功能深入了解我的组合元素并检查特定子元素的值。
I have a library that composes HTML elements using the DOM classes. I want to also use the DOM functionality to go deep into my composed elements and check specific child elements for values.
例如，这里的元素由名为 YesNoControl 的类生成：
For example, here's element produced by a class called YesNoControl:
<div id="yes_no">
<input id="yes_no_1" name="yes_no" value="1" type="radio"/>
<label for="yes_no_1">Yes</label>
<input id="yes_no_2" name="yes_no" value="2" type="radio"/>
<label for="yes_no_2">No</label>
</div>
PHPUnit测试应如下所示：
A PHPUnit test should look something like this:
$element = new YesNoControl();
$element_dom = $element->toDOMDocument(); // This method renders the object to a DOMDocument object.
$element_dom->validate();
$this->assertInstanceOf(\\DOMDocument::class, $element_dom);
$input = $element_dom->getElementById('yes_no_1');
$this->assertInstanceOf(\DOMNode::class, $input);
$this->assertEquals('1', $input->getAttribute('yes_no_1'));
问题是 $ input 总是出现返回 null 。
The problem is that $input always comes back null.
在我的研究中，我发现 getElementById（）仅在文档具有DOCTYPE HTML标记的情况下有效。在我的构建器中，我以简单的方式创建文档：
In my research, I found that getElementById() works only if the document has a DOCTYPE HTML tag. In my builder, I'm creating the document the plain-and-simple way:
$document = new \DOMDocument();
我试图在这样创建文档后直接将实现标签添加到文档中：
I tried adding the implementation tag to the document directly after creating the document thusly:
$implementation = new \DOMImplementation();
$document->appendChild($implementation->createDocumentType('HTML'));
但是，这会产生带有<！DOCTYPE HTML> 插入错误，例如以下示例：
However, this produces invalid elements with the <!DOCTYPE HTML> incorrectly inserted, like this example:
<div id="yes_no">
<!DOCTYPE HTML>
<input id="yes_no_1" name="yes_no" value="1" type="radio"/>
<label for="yes_no_1">Yes</label>
<input id="yes_no_2" name="yes_no" value="2" type="radio"/>
<label for="yes_no_2">No</label>
</div>
我看到了很多答案，其中提到将<！DOCTYPE HTML> 解释为HTML（例如这一个） 。但是我不是从HTML开始的；我正在编写一个元素，然后让DOM库编写HTML。
I see quite a few answers that mention putting <!DOCTYPE HTML> into HTML being interpreted (e.g. this one). But I'm not starting from HTML; I'm composing an element and letting the DOM library write the HTML.
我也尝试过根据此答案即时创建实现：
$element_dom = $element->toDOMDocument(); // This method renders the object to a DOMDocument object.
$element_dom->validate();
$dtd = '<!ELEMENT input (#PCDATA)>';
$systemId = 'data://text/plain;base64,'.base64_encode($dtd);
$implementation = new \DOMImplementation;
$element_dom->appendChild($$implementation->createDocumentType('HTML', null, $systemId));
$input = $element_dom->getElementById('yes_no_1');
$this->assertInstanceOf(\DOMNode::class, $input);
// Failed asserting that null is an instance of class "DOMNode".
我也尝试过使用XPath来获取值：
I've also tried using XPath to get the value:
$xpath = new \DOMXPath($element_dom);
$input = $xpath->query("//*[@id=yes_no_1]")->item(0);
$this->assertInstanceOf(\DOMNode::class, $input);
// Failed asserting that null is an instance of class "DOMNode".
到目前为止，我没有尝试过。我如何构造测试，以便它可以找到 yes_no_1 ？
So far, nothing I have tried is working. How do I need to structure my test so that it can find yes_no_1?
推荐答案
在您的XPath版本中-您需要用双引号括住要检查的值
In your XPath version - you need quotes round the value your checking for
$input = $xpath->query("//*[@id='yes_no_1']")->item(0);
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