Parse the Scheduler RecurrenceRule with ical.net

Environment

Product

Scheduler for Progress® Telerik® UI for ASP.NET Core

Description

How can I parse the RecurrenceRule of the Scheduler and get the dates of all the occurrences in a recurring event?

Solution

You can use the ical.net library to parse the RecurrenceRule. The example below demonstrates how this can be done in the Create action, which will be called when a new recurring event is added in the Scheduler.

C#

    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            return View();
        }

        private List<AppointmentViewModel> appointments = new List<AppointmentViewModel> {
            new AppointmentViewModel {
                Description = "Task 1 Description",
                Title = "Task 1",
                Start = new DateTime(2020,6,17,12,00,00),
                End= new DateTime(2020,6,17,12,06,00),
                OwnerID = 1
            },
            new AppointmentViewModel {
                Description = "Task 2 Description",
                Title = "Task 2",
                Start = new DateTime(2020,6,17,14,00,00),
                End= new DateTime(2020,6,17,15,00,00),
                OwnerID = 2
            },
            new AppointmentViewModel {
                Title = "Test",
                Start = new DateTime(2020,6,17,10,00,00),
                End= new DateTime(2020,6,17,11,00,00),
                RecurrenceRule = "FREQ=DAILY;COUNT=3",
                OwnerID = 2
            }
        };

        public JsonResult Read([DataSourceRequest] DataSourceRequest request)
        {
            return Json(appointments.ToDataSourceResult(request));
        }

        public virtual JsonResult Delete([DataSourceRequest] DataSourceRequest request, AppointmentViewModel task)
        {
            if (ModelState.IsValid)
            {
                appointments.Remove(appointments.Where(x => x.AppointmentID == task.AppointmentID).FirstOrDefault());
            }

            return Json(new[] { task }.ToDataSourceResult(request, ModelState));
        }

        public virtual JsonResult Create([DataSourceRequest] DataSourceRequest request, AppointmentViewModel task)
        {
            if (task.RecurrenceRule != null)
            {
                //pass the event's RecurrenceRule to a new RecurrencePattern instance
                var rrule = new RecurrencePattern(task.RecurrenceRule);
                var vEvent = new CalendarEvent
                {
                    //create a CalendarEvent instance and pass the actual Start and End values of the event
                    DtStart = new CalDateTime(task.Start),
                    DtEnd = new CalDateTime(task.End),
                    RecurrenceRules = new List<RecurrencePattern> { rrule },
                };

                var calendar = new Ical.Net.Calendar();
                calendar.Events.Add(vEvent);

                //get the occurrences within a specified time period
                var startSearch = new CalDateTime(task.Start);
                var endSearch = new CalDateTime(new DateTime(2020, 6, 30, 00, 00, 00));
                var occurrences = calendar.GetOccurrences(startSearch, endSearch);

                foreach(Occurrence occurrence in occurrences)
                {
                    //iterate the occurrences. You can access their StartTime and EndTime like this:
                    DateTime start = occurrence.Period.StartTime.Value;
                    DateTime end = occurrence.Period.EndTime.Value;
                }
            }

            if (ModelState.IsValid)
            {
                task.AppointmentID = ++appointments.LastOrDefault().AppointmentID;
                appointments.Add(task);
            }

            return Json(new[] { task }.ToDataSourceResult(request, ModelState));
        }

        public virtual JsonResult Update([DataSourceRequest] DataSourceRequest request, AppointmentViewModel task)
        {
            if (ModelState.IsValid)
            {
                var appointmentToUpdate = appointments.Where(x => x.AppointmentID == task.AppointmentID).FirstOrDefault();
                if (appointmentToUpdate != null)
                {
                    appointmentToUpdate = task;
                }
            }

            return Json(new[] { task }.ToDataSourceResult(request, ModelState));
        }
    }

Razor

    @(Html.Kendo().Scheduler<TelerikAspNetCoreApp1.Models.AppointmentViewModel>()
        .Name("scheduler")
        .Date(new DateTime(2020, 6, 17))
        .StartTime(new DateTime(2020, 6, 17, 7, 00, 00))
        .Height(800)
        .AllDaySlot(false)
        .Group(group => group.Resources("Players"))
        .Views(views =>
        {
            views.DayView(dayView => { dayView.Selected(true); });
        })
        .Resources(resource =>
        {
        resource.Add(m => m.OwnerID)
            .Title("Owner")
            .Name("Players")
            .DataTextField("ResourceName")
            .DataValueField("ResourceID")
            .DataColorField("Color")
            .BindTo(new[] {
                    new { ResourceName = "Rate", ResourceID = 5},
                    new { ResourceName = "Holes", ResourceID = 6},
                    new { ResourceName = "Player 1", ResourceID = 1},
                    new { ResourceName = "Player 2", ResourceID = 2},
                    new { ResourceName = "Player 3", ResourceID = 3},
                    new { ResourceName = "Player 4", ResourceID = 4}
            });
        })
        .DataSource(d => d
            .Model(m =>
            {
                m.Id(f => f.AppointmentID);
                m.Field(f => f.Title).DefaultValue("No title");
                m.Field(f => f.OwnerID).DefaultValue(1);
                m.RecurrenceId(f => f.RecurrenceID);
            })
            .Read(r => r.Url(Url.Action("Read", "Home")))
            .Create(r => r.Url(Url.Action("Create", "Home")))
            .Destroy(r => r.Url(Url.Action("Delete", "Home")))
            .Update(r => r.Url(Url.Action("Update", "Home")))
        )
    )

C#

    public class AppointmentViewModel : ISchedulerEvent
    {
        public int AppointmentID { get; set; }
        public string Title { get; set; }
        public string Description { get; set; }

        private DateTime start;
        public DateTime Start
        {
            get
            {
                return start;
            }
            set
            {
                start = value.ToUniversalTime();
            }
        }

        public string StartTimezone { get; set; }

        private DateTime end;
        public DateTime End
        {
            get
            {
                return end;
            }
            set
            {
                end = value.ToUniversalTime();
            }
        }

        public string EndTimezone { get; set; }

        public string RecurrenceRule { get; set; }
        public int? RecurrenceID { get; set; }
        public string RecurrenceException { get; set; }
        public bool IsAllDay { get; set; }
        public int? OwnerID { get; set; }
    }

More ASP.NET Core Scheduler Resources

• ASP.NET Core Scheduler Documentation

• ASP.NET Core Scheduler Demos

• ASP.NET Core Scheduler Product Page

• Telerik UI for ASP.NET Core Video Onboarding Course (Free for trial users and license holders)

• Telerik UI for ASP.NET Core Forums

See Also

• Client-Side API Reference of the Scheduler for ASP.NET Core
• Server-Side API Reference of the Scheduler for ASP.NET Core
• Telerik UI for ASP.NET Core Breaking Changes
• Telerik UI for ASP.NET Core Knowledge Base