How do I tell Facebook which image to use when my page gets shared?
Facebook has a set of open-graph meta tags that it looks at to decide which image to show.
The keys one for the Facebook image are:
<meta property="og:image" content="http://ia.media-imdb.com/rock.jpg"/>
<meta property="og:image:secure_url" content="https://secure.example.com/ogp.jpg" />
and it should be present inside the <head></head> tag at the top of your page.
If these tags are not present, it will look for their older method of specifying an image: <link rel="image_src" href="/myimage.jpg"/>. If neither are present, Facebook will look at the content of your page and choose images from your page that meet its share image criteria: Image must be at least 200px by 200px, have a maximum aspect ratio of 3:1, and in PNG, JPEG or GIF format.
Can I specify multiple images to allow the user to select an image?
Yes, you just need to add multiple image meta tags in the order you want them to appear in. The user will then be presented with an image selector dialog:
I specified the appropriate image meta tags. Why isn't Facebook accepting the changes?
Once a url has been shared, Facebook's crawler, which has a user agent of facebookexternalhit/1.1 (+https://www.facebook.com/externalhit_uatext.php), will access your page and cache the meta information. To force Facebook servers to clear the cache, use the Facebook Url Debugger / Linter Tool that they launched in June 2010 to refresh the cache and troubleshoot any meta tag issues on your page.
Also, the images on the page must be publicly accessible to the Facebook crawler. You should specify absolute url's like http://example.com/yourimage.jpg instead of just /yourimage.jpg.
Can I update these meta tags with client side code like Javascript or jQuery?
No. Much like search engine crawlers, the Facebook scraper does not execute scripts so whatever meta tags are present when the page is downloaded are the meta tags that are used for image selection.
Adding these tags causes my page to no longer validate. How can I fix this?
You can add the necessary Facebook namespaces to your tag and your page should then pass validation:
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:og="http://ogp.me/ns#"
xmlns:fb="https://www.facebook.com/2008/fbml">
There is a "way" to get some part of fan list with their profile ids of some fanpage without token.
Get id of a fanpage with public graph data: http://graph.facebook.com/cocacola - Coca-Cola has 40796308305. UPDATE 2016.04.30: Facebook now requires access token to get page_id through graph so you can parse fanpage HTML syntax to get this id without any authorization from https://www.facebook.com/{PAGENAME} as in example below based on og tags present on the fanpage.- Get Coca-Cola's "like plugin" iframe display directly with some modified params: http://www.facebook.com/plugins/fan.php?connections=100&id=40796308305
- Now check the page sources, there are a lot of fans with links to their profiles, where you can find their profile ids or nicknames like: http://www.facebook.com/michal.semeniuk .
If you are interested only in profile ids use the graph api again - it will give you profile id directly: http://graph.facebook.com/michal.semeniuk UPDATE 2016.04.30: Facebook now requires access token to get such info. You can parse profile HTML syntax, just like in the first step meta tag is your best friend:
<meta property="al:android:url" content="fb://profile/{PROFILE_ID}" />
And now is the best part: try to refresh (F5) the link in point 2.. There is a new full set of another fans of Coca-Cola. Take only uniques and you will be able to get some nice, almost full list of fans.
-- UPDATE 2013.08.06 --
Why don't you use my ready PHP script to fetch some fans? :)
UPDATE 2016.04.30: Updated example script to use new methods after Facebook started to require access token to get public data from graph api.
function fetch_fb_fans($fanpage_name, $no_of_retries = 10, $pause = 500000 /* 500ms */){
$ret = array();
// prepare real like user agent and accept headers
$context = stream_context_create(array('http' => array('header' => 'User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/49.0.2623.108 Chrome/49.0.2623.108 Safari/537.36\r\nAccept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8\r\nAccept-encoding: gzip, deflate, sdch\r\nAccept-language: en-US,en;q=0.8,pl;q=0.6\r\n')));
// get page id from facebook html og tags for mobile apps
$fanpage_html = file_get_contents('https://www.facebook.com/' . $fanpage_name, false, $context);
if(!preg_match('{fb://page/(\d+)}', $fanpage_html, $id_matches)){
// invalid fanpage name
return $ret;
}
$url = 'http://www.facebook.com/plugins/fan.php?connections=100&id=' . $id_matches[1];
for($a = 0; $a < $no_of_retries; $a++){
$like_html = file_get_contents($url, false, $context);
preg_match_all('{href="https?://www\.facebook\.com/([a-zA-Z0-9\._-]+)" class="link" data-jsid="anchor" target="_blank"}', $like_html, $matches);
if(empty($matches[1])){
// failed to fetch any fans - convert returning array, cause it might be not empty
return array_keys($ret);
}else{
// merge profiles as array keys so they will stay unique
$ret = array_merge($ret, array_flip($matches[1]));
}
// don't get banned as flooder
usleep($pause);
}
return array_keys($ret);
}
print_r(fetch_fb_fans('TigerPolska', 2, 400000));
Best Answer
https://graph.facebook.com/[PAGEID]/members?limit=500&access_token=[oauthtoken]