Filter Outlook appointments by category

Question

I have written this code to find the total duration of all appointments of a specified category within a specified time range:

private readonly MAPIFolder _timing;

private int CalculateTotalDuration(DateTime start, DateTime end, string category)
{
    string filter = String.Format(
        "([Start] >= '{0:g}') AND ([End] <= '{1:g}') AND ([Categories] = '{2}')",
        start, end, category);
    return _timing.Items.Restrict(filter).Cast<AppointmentItem>().
        Sum(appt => appt.Duration);
}

This code results in the following exception when used with Russian version of Outlook (I did not test it with English version though):

System.Runtime.InteropServices.COMException was unhandled
  Message=Условие неверно.
  Source=Microsoft Outlook
  ErrorCode=-2147352567
  StackTrace:
       at Microsoft.Office.Interop.Outlook._Items.Restrict(String Filter)
       ...

When I replace [Categories] with [Категории], i.e.

string filter = String.Format(
    "([Start] >= '{0:g}') AND ([End] <= '{1:g}') AND ([Категории] = '{2}')",
    start, end, category);

it works with Russian version of Outlook. But obviously it will not work with other languages.

How to filter Outlook appointments by category in a multilanguage way?

Answer 1

Try to use a SQL query (prefix the query with "@SQL=") and use the DASL name for the Categories - http://schemas.microsoft.com/mapi/string/{00020329-0000-0000-C000-000000000046}/Keywords/0x0000101F or urn:schemas:mailheader:keywords.