PHP Scraping with curl - How can I debug - php

Question

I just learned what scrapping and cUrl is few hours ago, and since then I am playing with that. Nevertheless, I am facing something strange now. The here below code works fine with some sites and not with others (of course I modified the url and the xpath...). Note that I have no error raised when I test if curl_exec was executed properly. So the problem must come from somwhere after. Some my questions are as follows:
How can I check if the new DOMDocument as been created properly: if(??)
How can I check if the new DOMDocument has been populated properly with html?
...if a new DOMXPath object has been created?
Hope I was clear. Thank you in advance for your replies. Cheers. Marc
My php:
<?php
$target_url = "http://www.somesite.com";
$userAgent = 'Googlebot/2.1 (http://www.googlebot.com/bot.html)';
// make the cURL request to $target_url
$ch = curl_init();
curl_setopt($ch, CURLOPT_USERAGENT, $userAgent);
curl_setopt($ch, CURLOPT_URL,$target_url);
curl_setopt($ch, CURLOPT_FAILONERROR, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_AUTOREFERER, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,true);
curl_setopt($ch, CURLOPT_TIMEOUT, 10);
$html= curl_exec($ch);
if (!$html) {
echo "<br />cURL error number:" .curl_errno($ch);
echo "<br />cURL error:" . curl_error($ch);
exit;
}
// parse the html into a DOMDocument
$dom = new DOMDocument();
#$dom->loadHTML($html);
// grab all the on the page
$xpath = new DOMXPath($dom);
$hrefs = $xpath->query('somepath');
for ($i = 0; $i < $hrefs->length; $i++) {
$href = $hrefs->item($i);
$url = $href->getAttribute('href');
echo "<br />Link: $url";
}
?>

Answer 1

Use a try/catch to check if the document object was created, then check the return value of loadHTML() to determine if the HTML was loaded into the document. You can use a try/catch on the XPath object as well.
try
{
$dom = new DOMDocument();
$loaded = $dom->loadHTML($html);
if($loaded)
{
// loaded OK
}
else
{
// could not load HTML
}
}
catch(Exception $e)
{
// document could not be created, see $e->getMessage()
}

Answer 2

Problem solved. The error came from firebug who gave a wrong path. Big thanks to MrCode for his support...