Outlook Calendar Api: GetRecurrencePattern().Exceptions is Always Empty

Question

I am listening to the Items.ItemChange() event on a MAPIFolder, and triggering this event handler when it fires:

private async void monitor_AppointmentModified(object sender, EventArgs<AppointmentItem> e)
{
    var item = e.Value;
    Debug.Print("Outlook Appointment Modified: {0}", item.GlobalAppointmentID);

    try
    {
        var result =  await GCalUtils.ModifyEventAsync(item);
    }
    catch (Exception ex)
    {
        PrintToDebug(ex);
    }
}

Which calls a utility class to push the modified event to google calendar:

public static async Task<Event> ModifyEventAsync(AppointmentItem item, string calendarId = PrimaryCalendarId)
{
    var gCalEventId = item.UserProperties.Find(Resources.GCalId);

    var updateRequest = Service.Events.Update(item.AsGCalEvent(), calendarId, gCalEventId.Value.ToString());
    var result = await updateRequest.ExecuteAsync() as Event;
    if (result != null && item.IsRecurring) 
        ModifyRecurrences(item, calendarId, result.Id);

    return result;
}

...so if the item is a recurring AppointmentItem, I call ModifyRecurrences:

private static async void ModifyRecurrences(AppointmentItem item, string calendarId, string eventId)
{
    var exceptions = item.GetRecurrencePattern().Exceptions.Cast<Microsoft.Office.Interop.Outlook.Exception>().ToList();
    if (!exceptions.Any()) return;

   // other stuff happens... eventually... hopefully
}

... but regardless of what I actually did to an occurrence of the series, whether I move an item to a new time, adjust the start or end time, or delete the item entirely, the exceptions.Any() call always returns false. There are never any exceptions in the collection, and if I understand the concepts correctly then by modifying an instance of the recurring series I have just created an exception and it should show up in the Exceptions collection.

I suspect I may have a stale copy of the AppointmentItem, but I've not a clue how to verify that.

Dmitry Streblechenko Dmitry Streblechenko · Accepted Answer · 2015-09-20T00:16:26

This is a known problem in the Outlook Object Model - you will only see the exceptions later when the appointment is completely dereferenced and reopened. Which can be a while if that is the appointment you are editing at the moment.

If using Redemption is an option, you can bypass the Outlook cache and reopen the appointment as an RDOAppointmentItem object.

Redemption.RDOSession session = new Redemption.RDOSession();
session.MAPIOBJECT = item.Application.Session.MAPIOBJECT;
Redemption.RDOAppointmentItem rItem = (Redemption.RDOAppointmentItem)session.GetMessageFormID(item.EntryID);

Outlook Calendar Api: GetRecurrencePattern().Exceptions is Always Empty

1 Answers