extracting facebook photo id from a LONG url

Question

I have searched this website on how to extract facebook id from url that starts from photo.php?fbid= but i have a long url and know how to get photo id

Example1 : photo.php?fbid=10151987845617397 (the complete url is stored in the $url variable which is checked using preg_match i believe)

!preg_match("|^http(s)?://(www.)?facebook.com/photo.php(.*)?$|i", $url) || !$pid

the above code fetches facebook id 10151987845617397 and puts it in the variable $pid.

If I have a long url, how can i change the code? Here is the url Example2 : https://www.facebook.com/nokia/photos/a.338008237396.161268.36922302396/10151987845617397/?type=1&theater In the above url 10151987845617397 is the photo id that i need to capture and put it in variable $pid.

what changes do i need to do in the preg_match string?

In other words to get the photoid 10151987845617397 as output in the $pid variable:

For url facebookcom/photo.php?fbid=10151987845617397 The syntax is !preg_match("|^http(s)?://(www.)?facebook.com/photo.php(.*)?$|i", $url) || !$pid

So for url facebookcom/nokia/photos/a.338008237396.161268.36922302396/10151987845617397/?type=1&theater What would be the syntax

Please help Thanks

Answer 1

The simple solution and quite readable: Use the entire string as a regex, use () around what you want to match:

// $tmp[1] = www or nothing
// $tmp[2] = "user" (i.e nokia)
// $tmp[3] = album id?
// $tmp[4] = photos
// $tmp[5] = Long url as requested
function extract_id_from_album_url($url) {
    preg_match('/https?:\/\/(www.)?facebook\.com\/([a-zA-Z0-9_\- ]*)\/([a-zA-Z0-9_\- ]*)\/([a-zA-Z0-9_\.\-]*)\/([a-zA-Z0-9_\-]*)(\/\?type=1&theater\/)?/i', $url, $tmp);

    return isset($tmp[5]) ? $tmp[5] : false;
}

Backslashes are needed to ensure the . is seen as a literal (and not regex syntax). Questionmarks to allow optional urls. Using more regex syntax can make the matching "query" much shorter and extendable, but also makes it harder to read.