Facebook Graph API v2.1: getting user id and his posts

Question

Imagine the situation when I'm logged in facebook web application as userA. I know userB's nickname but he is not in my friendlist and I do not know his id. And, of course, he does not use my app.

1. How can I get userB's id via a nickname?
2. After that how can I get his wall posts?

Are there any specific permissions? May be there are manual pages I've missed?

Answer 1

In v1.0, the following was possible:

http://graph.facebook.com/v1.0/{user-name}

However, with v2.0 and v2.1, accessing users via IDs or Usernames not connected to your application is not possible. E.g., trying http://graph.facebook.com/v2.1/{user-name} will throw an error:

{
   "error": {
      "message": "(#803) Cannot query users by their username (user-name)",
      "type": "OAuthException",
      "code": 803
   }
}

Using the new PHP SDK (v4.0.x) you can do the following:

$response = (new FacebookRequest( $session, 'GET', '{user-name}', array(), 'v1.0' ))->execute()->getGraphObject()->asArray();