DOMXpath - Get href attribute and text value of an a element

问题

So I have a HTML string like this:

<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:

 $domXpath = new \DOMXPath($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:

 // 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?).

回答1:

Fetch

//td[@class='name']/a

and then pluck the text with nodeValue and the attribute with getAttribute('href').

Apart from that, you can combine Xpath queries with the Union Operator | so you can use

//td[@class='name']/a/@href|//td[@class='name']

as well.

回答2:

To reduce the code to a single loop, try:

$anchors = $domXpath->query("//td[@class='name']/a");
foreach($anchors as $a)
{ 
    print $a->nodeValue." - ".$a->getAttribute("href")."<br/>";
}

As per above :) Too slow ..

回答3:

Simplest way, `evaluate` is for this task!

The simplest way to obtain a value is by evaluate() method:

$xp = new DOMXPath($dom);
$v = $xp->evaluate("string(/etc[1]/@stringValue)");

Note: important to limit XPath returns to 1 item (the first a in this case), and cast the value with string() or round(), etc.

So, in a set of multiple items, using your foreach code,

 $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.