Oddities of Facebook events API

Using the the Graph API of https://graph.facebook.com/[userId]/events, one can retrieve the events that the user is attending. The same applies to page, using https://graph.facebook.com/[pageId]/events. However, what does it mean by the event attended by a page? It is not the same as the events created by the page, as the API returns less results that what you would see in the events tab of the page. The result return from FQL and REST API are similar.

After spending an entire day figuring out what happens behind the scene, I came to the following conclusion:

1. User A creates Page P.
2. User A makes User B also the admin of Page P.

During creation of event:

1. If User A creates event on Page P, Page P will be attending the event.
2. If User B creates event on Page P, Page P will not be attending the event.

Unfortunately, as FQL does not allow querying the event by its creator, there is hence no way to fool-proof way to get the events that a page has created.

Oddities of Facebook event date/time

Facebook is very popular globally, crossing several time zones. Yet to my surprise, it has no concept of time zones. Quote from the Legacy REST API

Note that the start_time and end_time are the times that were inputted by the event creator. Facebook Events have no concept of timezone, so, in general, you can should not treat the value returned as occurring at any particular absolute time. When an event is displayed on facebook, no timezone is specified or implied.

However, using the Graph API to retrieve events of a page, I got the following:

{
  "data":
  [
    {
      "name":"Event Name",
      "start_time":"2010-11-20T02:30:00+0000",
      "end_time":"2010-11-20T03:00:00+0000",
      "location":"5th Street",
      "id":"1234"
    }
  ],
  "paging":
  {
    "previous":"https:\/\/graph.facebook.com\/11\/events?access_token=15\u00257&limit=5000&since=2010-11-20T02\u00253A30\u00253A00\u00252B0000",
    "next":"https:\/\/graph.facebook.com\/11\/events?access_token=15\u00257&limit=5000&until=2010-09-22T01\u00253A29\u00253A59\u00252B0000"
  }
}

The start_time and end_time are displayed as GMT+0. These times are 8 hours late. On some other events, they are 7 hours late. Clearly, Facebook is trying to store the time in GMT, but isn’t using the correct time zone where I am at.

According to http://www.webos-internals.org/wiki/Facebook_timezone_issue, Facebook assumes all time to be in Pacific Time. Thus the GMT-8 during Standard Time and GMT-7 during Daylight Savings.

In order to use the time from the Graph API, I used the TimeZoneInfo to convert the time from GMT to Pacific Time. Code as follows

private static PacificDateTime StringToDate(string value)

{

    DateTime fakeUtc = DateTime.Parse(value, CultureInfo.InvariantCulture, DateTimeStyles.AdjustToUniversal);

    // See http://www.webos-internals.org/wiki/Facebook_timezone_issue.

    // Facebook assumes all time in events to be in Pacific Time.

    const string pacificTimeZoneId = "Pacific Standard Time";

    TimeZoneInfo pacificTimeZone = TimeZoneInfo.FindSystemTimeZoneById(pacificTimeZoneId);

    DateTime pacificTime = TimeZoneInfo.ConvertTimeFromUtc(fakeUtc, pacificTimeZone);

    return new PacificDateTime(pacificTime, pacificTimeZone.IsAmbiguousTime(pacificTime));

}

By treating all times as Pacific Time, Facebook introduced oddities to places that do not practise daylight savings, or that has daylight savings on a different schedule. Effectively, there is no way for me to meet on 13 March 2011 at 2.30am. Since daylight savings starts at 2am on the 2nd Sunday of March, and it adjusts the clock to 3am, 2.30am is an invalid time in Pacific Time. Events specified as 2.30am becomes 3.30am.

On the 6 November 2011, daylight savings ends and the clock jumps back an hour. This creates ambiguous time between 1am and 2am, which Facebook behaves in a very weird way when creating events that are at that time. Try it for yourself.