How to check if a URL is a valid RSS feed in PHP

Question

I have the following code:

    function parse() {
        $content = file_get_contents($this->feed);        
        $rss = new SimpleXmlElement($content);
        $rss_split = array();
        $i = 0;
        foreach ($rss->channel->item as $item) {
            $title = (string) $item->title; // Title
            $link = (string) $item->link; // Url Link            
            $content = $item->children('content', true)->encoded;
            preg_match('/<img.+src=[\'"](?P<src>.+)[\'"].*>/i', $content, $image);
            $image = substr($image['src'], 0, strpos($image['src'], '"'));
            $rss_split[$i]['title'] = $title;
            $rss_split[$i]['link'] = $link;
            $rss_split[$i]['image'] = $image;
            $i++;
        }
        return $rss_split;
    }

Here, $this->feed contains the RSS feed's URL. The problem is I do not know how to validate the URL to be sure it is a valid RSS feed.

Answer 1

To verify that it is XML:

function parse()
{
    $content = file_get_contents($this->feed); 
    try { $rss = new SimpleXmlElement($content); }
    catch(Exception $e){ /* the data provided is not valid XML */ return false; }
    // rest of your function goes here

Once you have verified that it is XML you have a couple of options:

1. you could check to make sure isset($rss->channel->item) existed and $rss->channel->item->count() > 0.
2. You can use count($rss->xpath(/channel/item)) > 0.

I'd use xpath, personally as I find it a little more obvious when reading the code.

---

SIDE NOTE:

Seriously? You've already got XML object. Why are you using RegEx?

Don't do this:

preg_match('/<img.+src=[\'"](?P<src>.+)[\'"].*>/i', $content, $image);

When this is a valid option:

$g = $item->xpath('//img'); $g[0]->attributes()->src;

Answer 2

May this will helpfull to you.

?php

function validateFeed( $sFeedURL )
{

$sValidator = 'http://feedvalidator.org/check.cgi?url=';

if( $sValidationResponse = @file_get_contents($sValidator . urlencode($sFeedURL)) )
{
    if( stristr( $sValidationResponse , 'This is a valid RSS feed' ) !== false )
    {
        return true;
    }
    else
    {
        return false;
    }
}
else
{
    return false;
}
}

?>