php DOMXpath - 获取 a 元素的 href 属性和文本值
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/6820429/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
DOMXpath - Get href attribute and text value of an a element
提问by Marko Jovanovi?
So I have a HTML string like this:
所以我有一个像这样的 HTML 字符串：
<td class="name">
<a href="/blah/somename23123">Some Name</a>
</td>
<td class="name">
<a href="/blah/somename28787">Some Name2</a>
</td>
Using XPath I'm able to get value of href attribute using this Xpath query:
使用 XPath，我可以使用此 Xpath 查询获取 href 属性的值：
$domXpath = new \DOMXPath($this->domPage);
$hrefs = $domXpath->query("//td[@class='name']/a/@href");
foreach($hrefs as $href) {...}
And It's even easier to get a text value, like this:
获取文本值更容易，如下所示：
// Xpath auto. strips any html tags so we are
// left with clean text value of a element
$domXpath = new \DOMXPath($this->domPage);
$names = $domXpath->query("//td[@class='name']/");
foreach($names as $name) {...}
Now I'm curious to know, how can I combine those two queries to get both values with only one query (If it's something like that even posible?).
现在我很想知道，我怎样才能将这两个查询结合起来只用一个查询来获得两个值（如果它甚至可能是这样的？）。
回答by Gordon
Fetch
拿来
//td[@class='name']/a
and then pluck the text with nodeValueand the attribute with getAttribute('href').
然后用 提取文本nodeValue和属性getAttribute('href')。
Apart from that, you can combine Xpath queries with the Union Operator |so you can use
除此之外，您可以将 Xpath 查询与联合运算符结合使用，|以便您可以使用
//td[@class='name']/a/@href|//td[@class='name']
as well.
以及。
回答by Ryan
To reduce the code to a single loop, try:
要将代码减少到单个循环，请尝试：
$anchors = $domXpath->query("//td[@class='name']/a");
foreach($anchors as $a)
{
print $a->nodeValue." - ".$a->getAttribute("href")."<br/>";
}
As per above :) Too slow ..
如上所述:) 太慢了..
回答by Peter Krauss
Simplest way, evaluateis for this task!
最简单的方法，evaluate就是为了这个任务！
The simplest way to obtain a value is by evaluate()method:
获取值的最简单方法是通过evaluate()方法：
$xp = new DOMXPath($dom);
$v = $xp->evaluate("string(/etc[1]/@stringValue)");
Note: important to limit XPath returns to 1 item (the first ain this case), and castthe value with string()or round(), etc.
注意：将 XPath 限制为 1 项（a在本例中为第一项）并使用or等强制转换值很重要。string()round()
So, in a set of multiple items, using your foreachcode,
因此，在一组多个项目中，使用您的foreach代码，
$names = $domXpath->query("//td[@class='name']/");
foreach($names as $contextNode) {
$text = $domXpath->evaluate("string(./a[1])",$contextNode);
$href = $domXpath->evaluate("string(./a[1]/@href)",$contextNode);
}
PS: this example is only for evaluate's illustration... When the information already exists at the node, use what offers best performance, as methods getAttribute(), saveXML(), etc. and properties as $nodeValue, $textContent, etc. supplied by DOMNode.
See @Gordon's answer for this particular problem.
The XPath subquery(at context) is good for complex cases — or symplify your code, avoiding to check hasChildNodes()+ loop for $childNodes, etc. with no significative gain in performance.
PS：这个例子只是为了evaluate的说明......当信息的节点，利用已经存在哪些优惠最佳的性能，如方法getAttribute()，saveXML()等和性能$nodeValue，$textContent等的供应DOMNode。
有关此特定问题，请参阅 @Gordon 的回答。
该XPath的子查询（在上下文中）是复杂的情况下，良好的-或symplify你的代码，避免检查hasChildNodes（）+循环为$的childNodes，等在性能无显着性收益。
