关于php：Xpath查询不会返回结果

Xpath Query Won't Return Results

我正在尝试从Xpath查询返回一些结果，但不会正确选择元素。我正在使用以下代码：

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public function getTrustPilotReviews($amount)
{
$trustPilotUrl = 'https://www.trustpilot.co.uk/review/purplegriffon.com';
$html5 = new HTML5;
$document = $html5->loadHtml(file_get_contents($trustPilotUrl));
$document->validateOnParse = true;
$xpath = new DOMXpath($document);
$reviewsDomNodeList = $xpath->query('//div[@id="reviews-container"]//div[@itemprop="review"]');
$reviews = new Collection;

foreach ($reviewsDomNodeList as $key => $reviewDomElement)
{
$xpath = new DOMXpath($reviewDomElement->ownerDocument);

if ((int) $xpath->query('//*[@itemprop="ratingValue"]')->item($key)->getAttribute('content') >= 4)
{
$review = [
'title' => 'Test',
'author' => $xpath->query('//*[@itemprop="author"]')->item($key)->nodeValue,
'date' => $xpath->query('//*[@class="ndate"]')->item($key)->nodeValue,
'rating' => $xpath->query('//*[@itemprop="ratingValue"]')->item($key)->nodeValue,
'body' => $xpath->query('//*[@itemprop="reviewBody"]')->item($key)->nodeValue,
];

$reviews->add((object) $review);
}
}

return $reviews->take($amount);
}

此代码不会返回任何内容：

1	//div[@id="reviews-container"]//div[@itemprop="review"]

但是如果我将其更改为：

1	//[@id="reviews-container"]//[@itemprop="review"]

它部分起作用，但是不能返回正确的结果。

您似乎正在使用HTML5-PHP库。如果需要，则需要使用名称空间。该库将HTML5加载到XHTML文档中。您可以测试是否将DOM文档另存为XML。输出将类似于：

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<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml">
...
</html>

因此，如果您使用XPath，则需要为XHTML名称空间注册并添加前缀，并将其用作元素名称。

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...
$xpath = new DOMXPath($document);
$xpath->registerNamespace('x', 'http://www.w3.org/1999/xhtml');

$reviewNodes= $xpath->evaluate(
'//x:div[@id="reviews-container"]//x:div[@itemprop="review"]'
);
foreach ($reviewNodes as $reviewNode) {
...
}
...

循环中有一个条件，该条件可以是用于获取评论的外部XPath的一部分：

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$expression =
'//x:div[@id="reviews-container"]
//x:div[
@itemprop="review" and
(.//*[@itemprop ="ratingValue"]/@content > 4)
]'

不要使用DOMXPath::query()，而要使用DOMXPath::evaluate()，它可以直接获取标量。方法的第二个参数是上下文节点。使用相对位置路径(在表达式的开头没有/)。

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...
foreach ($reviewNodes as $reviewNode) {
$review = [
'title' => 'Test',
'author'=> $xpath->evaluate('string(.//*@itemprop="author"])', $reviewNode),
'date'=> $xpath->evaluate('string(.//*[@class="ndate"])', $reviewNode),
'rating'=> $xpath->evaluate('string(.//*[@class="ratingValue"])', $reviewNode),
'body'=> $xpath->evaluate('string(.//*[@class="reviewBody"])', $reviewNode)
];
...
}

由于在## php IRC中使用了Viper-7，biberu和salathe，我现在可以使用：

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public function getTrustPilotReviews($amount)
{
$context = stream_context_create(array('ssl' => array('verify_peer' => false)));

$url = 'https://www.trustpilot.co.uk/review/purplegriffon.com';
$data = file_get_contents($url, false, $context);

libxml_use_internal_errors(true);

$doc = new \\DOMDocument();
$doc->loadHTML($data);

$xpath = new DOMXpath($doc);

$reviews = new Collection;

foreach($xpath->query('//div[@id="reviews-container"]/div[@itemprop="review"]') as $node)
{
$xpath = new DOMXpath($doc);
$rating = $xpath->query('.//*[@itemprop="ratingValue"]', $node)->item(0)->getAttribute('content');

if ($rating >= 4)
{
$review = [
'title' => $xpath->evaluate('normalize-space(descendant::*[@itemprop="headline"]/a)', $node),
'author' => $xpath->evaluate('normalize-space(descendant::*[@itemprop="author"])', $node),
'date' => $xpath->evaluate('normalize-space(descendant::*[@class="ndate"])', $node),
'rating' => $xpath->evaluate('number(descendant::*[@itemprop="ratingValue"]/@content)', $node),
'body' => $xpath->evaluate('normalize-space(descendant::*[@itemprop="reviewBody"])', $node),
];

$reviews->add((object) $review);
}
}

return $reviews->take($amount);
}