使用xpath和php从html页面检索数据

Question

I know there are similar question, but, trying to study PHP I met this error and I want understand why this occurs.

<?php
    $url = 'http://aice.anie.it/quotazione-lme-rame/';
    echo "hello!\r\n";
    $html = new DOMDocument();
    @$html->loadHTML($url);
    $xpath = new DOMXPath($html);
    $nodelist = $xpath->query(".//*[@id='table33']/tbody/tr[2]/td[3]/b");

    foreach ($nodelist as $n) {
        echo $n->nodeValue . "\n";
    }
?>

this prints just "hello!". I want to print the value extracted with the xpath, but the last echo doesn't do anything.

Answer 1

You have some errors in your code :

1. You try to get the table from the url http://aice.anie.it/quotazione-lme-rame/ , but it's actually in an iframe located at http://www.aiceweb.it/it/frame_rame.asp , so get the iframe url directly.

2. You use the function loadHTML(), which load an HTML string . What you need is the loadHTMLFile function, which takes the link of an HTML document as a parameter (See http://www.php.net/manual/fr/domdocument.loadhtmlfile.php )

3. You assume there is a tbody element on the page but there is no one. So remove that from your query filter.

Working code :

$url = 'http://www.aiceweb.it/it/frame_rame.asp';
echo "hello!\r\n";
$html = new DOMDocument();
@$html->loadHTMLFile($url);
$xpath = new DOMXPath($html);
$nodelist = $xpath->query(".//*[@id='table33']/tr[2]/td[3]/b");

foreach ($nodelist as $n) {
    echo $n->nodeValue . "\n";
}