Question

Scenario:

1. User A send application request to user B
2. User B accepts request
3. after accepting request, I want User A’s facebook ID who actually sent request

In short I want inviting user on application request accept event of invitee user.

Answer 1

You can get the details on request (including creator details) by querying Graph API with ID of request (you have list of accepting request ids in request_ids parameter passed to you app canvas):

https://graph.facebook.com/REQUEST_ID

This will return details in following format (as described in requests documentation, see “Accepting an App Request / Request ID Format”):

{
  "id": "REQUEST_OBJECT_ID", 
  "application": {
    "name": "APP_DISPLAY_NAME", 
    "canvas_name": "APP_NAME",  // This is identical to the app namespace
    "namespace": "APP_NAMESPACE", 
    "id": "APP_ID"
  }, 
  "from": {
    "name": "SENDER_USER_NAME", 
    "id": "SEND_USER_ID"
  }, 
  "message": "Check out this Awesome Request!", 
  "created_time": "2012-01-24T00:43:22+0000", 
  "type": "apprequest"
}