Check whether image exists on remote URL

Question

I am generating dynamic URLs of images for book ISBNs. I need a reliable way with PHP to check whether the images actually exist at the remote url. I tried various approaches with different PHP libraries, curl, etc., but none of them works well, some of them are downright slow. Given the fact that I need to generate (and check!) about 60 URLS for each book in my database, this is a huge waiting time. Any clues?

Answer 1

function checkRemoteFile($url)
{
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL,$url);
    // don't download content
    curl_setopt($ch, CURLOPT_NOBODY, 1);
    curl_setopt($ch, CURLOPT_FAILONERROR, 1);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

    $result = curl_exec($ch);
    curl_close($ch);
    if($result !== FALSE)
    {
        return true;
    }
    else
    {
        return false;
    }
}

--> that is the fastest way if your host supports curl

Answer 2

Use getimagesize() method like this

$external_link = ‘http://www.example.com/example.jpg’;
if (@getimagesize($external_link)) {
echo  “image exists “;
} else {
echo  “image does not exist “;
}

Answer 3

There is no "easy" way here - at a very minimum, you need to generate a HEAD request and check the resulting content type to make sure it's an image. That's not taking into account possible referrer issues. curl is the way to go here.

Answer 4

You could use curl. Just set the curl option CURLOPT_NOBODY to true. This will skip body information and only get the head (thus http code as well). Then, you could use the CURLOPT_FAILONERROR to turn this whole process into a true/false type check