MZOutlookAppointmentTools

This library simplifies the creation of recurring Outlook AppointmentItems using standard iCalendar recurrence patterns. It also enables the retrieval of recurrence pattern strings from existing Outlook recurring AppointmentItems. Currently the library provides some tools to parse,generate and compare iCalendar recurrence rules for Outlook appointment items

Limitations

1. The library currently just supports these recurrence types: "DAILY" / "WEEKLY" / "MONTHLY" / "YEARLY". This is because these are the only supported types by Outlook. As a consequence all the related keywords (e.g. "BYHOUR","BYMINUTE","BYSECOND") are not supported.
2. The "WKST" is not supported as it seems that there are no way to handle it in Outlook.
3. Patterns containing "BYWEEKNO" are not supported.
4. Patterns containing BYDAY with numbers such as "FREQ=MONTHLY;INTERVAL=1;BYDAY=1FR,3MO" Are not supported

Supported Pattern Samples

• "FREQ=WEEKLY;BYDAY=SA"
• "FREQ=WEEKLY;BYDAY=MO,TU,WE"
• "FREQ=WEEKLY;BYDAY=MO,TU,WE;INTERVAL=2"
• "FREQ=MONTHLY;BYMONTHDAY=12"
• "FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=1"
• "FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-1"
• "FREQ=YEARLY;BYMONTHDAY=7;BYMONTH=3"
• "FREQ=YEARLY;BYDAY=FR;BYMONTH=11;BYSETPOS=2"
• "FREQ=YEARLY;BYDAY=FR;BYMONTH=11;BYSETPOS=3;INTERVAL=3"
• "FREQ=YEARLY;BYDAY=MO,TU,WE,TH,FR;BYMONTH=9;BYSETPOS=1"

Usage:

SetRecurrencePattern:

 AppointmentItem aItem = (AppointmentItem)ApplicationInstance.CreateItem(OlItemType.olAppointmentItem);
 string pattern = "FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR";
 RecurrenceStringTools.SetRecurrencePattern(pattern, aItem, itemStart);
 var recPattern = aItem.GetRecurrencePattern();
//Expected values:
//  recPattern.RecurrenceType == OlRecurrenceType.olRecursWeekly
//  recPattern.DayOfWeekMask == OlDaysOfWeek.olMonday | OlDaysOfWeek.olTuesday | OlDaysOfWeek.olWednesday | OlDaysOfWeek.olThursday | OlDaysOfWeek.olFriday
//  recPattern.Instance == 0
//  recPattern.Interval == 1

GetRecurrencePattern

 AppointmentItem aItem = (AppointmentItem)ApplicationInstance.CreateItem(OlItemType.olAppointmentItem);
 var occ = aItem.GetRecurrencePattern();
 occ.RecurrenceType = OlRecurrenceType.olRecursDaily;
 occ.Interval = 1;
 aItem.Save();
 var item = RecurrenceStringTools.GetRecurrenceString(aItem); // "FREQ=DAILY;INTERVAL=1"

AreEqual

  string pattern1 = "FREQ=WEEKLY;BYDAY=MO,TU,WE";
  string pattern2 = "FREQ=WEEKLY;BYDAY=TU,WE,MO";
  var areEqual = RecurrenceStringTools.AreEqual(pattern1, pattern2);// true

More samples could be found in the test project.

Discution

1. This pattern "FREQ=MONTHLY;INTERVAL=1;BYDAY=FR" would be converted to a olRecursWeekly as olRecursMonthNth requires the instance field to be set to a value from 1 to 5. So when it is converted back to recurrence rule the value would be simply "FREQ=WEEKLY;INTERVAL=1;BYDAY=FR" (Check these tests: Combo_MonthlyNthSetPos_Existence1 and Combo_MonthlyNthSetPos_Existence2 in RecurrenceStringToolsTest). Moreover, whenever we get the recurrence pattern from an AppointmentItem with olRecursMonthNth, we always include the "BYSETPOS".