RadControls for ASP.NET AJAX RadScheduler includes support for recurring events on hourly, weekly, daily, monthly and yearly basis.
Exceptions to the recurrence rules are also permitted. To support this recurrence behavior, the Appointment
class includes the RecurrenceRule, RecurrenceParentID and
RecurrenceState properties. When an appointment is promoted into a recurring event its
RecurrenceState changes to RecurrenceState.Master and the
RecurrenceRule is populated with the string representation of the recurrence rule.
The recurrence master is stored in the database and its occurrences are generated on the fly with
RecurrenceState set to RecurrenceState.Occurrence.
If the user modifies an individual appointment occurrence, this creates an exception. The RecurrenceRule
of the master is modified to include the date and time of the exception so that no occurrence is generated for the exception occurrence.
Then the exception is stored in the database and its RecurrenceParentID property is set to reference the original
master. This way the exception is still linked to the original recurrence series.
The RecurrenceRule class is the engine for creating and evaluating recurrence rules. It serves as a
base class to several specialized classes and cannot be instantiated directly. The specialized classes are:
HourlyRecurrenceRule
DailyRecurrenceRule
WeeklyRecurrenceRule
MonthlyRecurrenceRule
YearlyRecurrenceRule
Using the specialized classes makes it easier to define recurrence rules because only relevant parameters are specified in
their constructors.
Example
Here is an example using the HourlyRecurrenceRule class:
CopyC#
using System;
using Telerik.Web.UI;
namespace RecurrenceExamples
{
class ParsingExample
{
static void Main()
{
Appointment recurringAppointment =
new Appointment("1",
Convert.ToDateTime("6/1/2007 3:30 PM").ToUniversalTime(),
Convert.ToDateTime( "6/1/2007 4:00 PM").ToUniversalTime(),
"Sample appointment");
RecurrenceRange range = new RecurrenceRange();
range.Start = recurringAppointment.Start;
range.EventDuration = recurringAppointment.End - recurringAppointment.Start;
range.MaxOccurrences = 10;
HourlyRecurrenceRule rrule = new HourlyRecurrenceRule(2, range);
Console.WriteLine("The appointment recurs at the following times");
foreach (DateTime occurrence in rrule.Occurrences)
{
Console.WriteLine( "\t{0}", occurrence);
}
Console.WriteLine();
string rruleAsString = rrule.ToString();
Console.WriteLine("Recurrence rule:\n\n{0}\n", rruleAsString);
RecurrenceRule parsedRule;
RecurrenceRule.TryParse(rruleAsString, out parsedRule);
Console.WriteLine("After parsing (should be the same):\n\n{0}", parsedRule);
}
}
}CopyVB.NET
Imports System
Imports Telerik.Web.UI
Namespace RecurrenceExamples
Class ParsingExample
Shared Sub Main()
Dim recurringAppointment As New Appointment("1", Convert.ToDateTime("6/1/2007 3:30 PM").ToUniversalTime(), Convert.ToDateTime("6/1/2007 4:00 PM").ToUniversalTime(), "Sample appointment")
Dim range As New RecurrenceRange()
range.Start = recurringAppointment.Start
range.EventDuration = recurringAppointment.[End] - recurringAppointment.Start
range.MaxOccurrences = 10
Dim rrule As New HourlyRecurrenceRule(2, range)
Console.WriteLine("The appointment recurs at the following times")
For Each occurrence As DateTime In rrule.Occurrences
Console.WriteLine("" & Chr(9) & "{0}", occurrence)
Next
Console.WriteLine()
Dim rruleAsString As String = rrule.ToString()
Console.WriteLine("Recurrence rule:" & Chr(10) & "" & Chr(10) & "{0}" & Chr(10) & "", rruleAsString)
Dim parsedRule As RecurrenceRule
RecurrenceRule.TryParse(rruleAsString, parsedRule)
Console.WriteLine("After parsing (should be the same):" & Chr(10) & "" & Chr(10) & "{0}", parsedRule)
End Sub
End Class
End Namespace
The RecurrenceRange class specifies the time frame for the recurrence. It consists of the start time
of the event, it's duration and optional limits.
The Occurrences property returns an enumerator that can be used to retrieve all the occurrences defined by the rule.
The RecurrenceRule class supports the ToString and TryParse
methods that RadScheduler uses for storing and retrieving the recurrence rules instances. The format is a subset
of the standard iCalendar format. The example above produces the following output: