How to get information about a Facebook group by its address?

Question

Facebook

The input is the URL of the group, which does not contain its identifier. For example, https://www.facebook.com/groups/primorye/
How, having such an address and not having a user token (there is an application token), automatically get the group ID or information about the group (in the Graph API format )?

Answer 1

I found a dirty way: parse the identifier from the HTML code of the page on the main site https://www.facebook.com/groups/адрес_группы/. And then get information about the group through the Graph API.
An example of getting the group ID in PHP:

function getGroupID( $name )
{
    $url = 'https://www.facebook.com/groups/' . urlencode( $name ) . '/';

    $curl = curl_init( $url );
    curl_setopt( $curl, CURLOPT_TIMEOUT, 10 );
    curl_setopt( $curl, CURLOPT_RETURNTRANSFER, 1 );
    curl_setopt( $curl, CURLOPT_USERAGENT, "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/601.7.7 (KHTML, like Gecko) Version/9.1.2 Safari/601.7.7" );  // Иначе Facebook не отдаст ответ
    $html = curl_exec( $curl );
    curl_close($curl);

    if ( preg_match( '~"fb://group/(?:\?id=|.{0})([0-9]+)"~u', $html, $matches ) )
       return (int)$matches[ 1 ];

    if ( preg_match( '~"group_id"\s*:\s*([0-9]+)~u', $html, $matches ) )
       return (int)$matches[ 1 ];

    if ( preg_match( '~"/ajax/groups/membership[^"]+group_id=([0-9]+)"~u', $html, $matches ) )
       return (int)$matches[ 1 ];

    if ( preg_match( '~"/ajax/timeline/sign_up_dialog[^"]+entity_id=([0-9]+)["&;]~u', $html, $matches ) )
       return (int)$matches[ 1 ];

    return null;
}

var_dump( getGroupID( 'primorye' ) );