Recurrence Editor

14 Jul 202314 minutes to read

The Recurrence editor is integrated into Scheduler editor window by default, to process the recurrence rule generation for events. Apart from this, it can also be used as an individual component referring from the Scheduler repository to work with the recurrence related processes.

All the valid recurrence rule string mentioned in the iCalendar specifications are applicable to use with the recurrence editor.

Customizing the repeat type option in editor

By default, there are 5 types of repeat options available in recurrence editor such as,

• Never
• Daily
• Weekly
• Monthly
• Yearly

It is possible to customize the recurrence editor to display only the specific repeat options such as Daily and Weekly options alone by setting the appropriate Frequencies option.

@using Syncfusion.Blazor.Schedule

<SfRecurrenceEditor Frequencies="@Repeats"></SfRecurrenceEditor>

@code {
    List<RepeatType> Repeats = new List<RepeatType>()
    {
       RepeatType.None, RepeatType.Daily, RepeatType.Weekly
    };
}

The other properties available in the recurrence editor are tabulated below,

Properties	Type	Description
FirstDayOfWeek	int	Sets the first day of the week on the recurrence editor.
StartDate	DateTime	Sets the start date from which date the recurrence event starts.
DateFormat	string	Sets the specific date format on the recurrence editor.
ChildContent	RenderFragment	sets the child content of the Recurrence editor.
CssClass	string	Allows styling to be applied on the recurrence editor with custom class names.
EnableRtl	bool	Allows recurrence editor to render in RTL mode.
MinDate	DateTime	Sets the minimum date on the recurrence editor.
MaxDate	DateTime	Sets the maximum date on the recurrence editor.
SelectedType	RepeatType	Sets the specific repeat type on the recurrence editor.
EndTypes	List	Sets the types that can be used to define the end condition for a recurrence editor.
Frequencies	List	Sets the recurrence pattern on the editor.

Customizing the end type option in Editor

By default, there are 3 types of end options available in the recurrence editor such as:

• Never
• Until
• Count

It is possible to customize the recurrence editor to display only the specific end options, such as the Until and Count options alone, by setting the appropriate EndTypes option.

@using Syncfusion.Blazor.Schedule

<SfRecurrenceEditor EndTypes="@Endtypes"></SfRecurrenceEditor>

@code {
    List<EndType> Endtypes = new List<EndType>()
    {
       EndType.Until, EndType.Count
    };
}

Accessing the recurrence rule string

The recurrence rule is usually generated based on the options selected from the recurrence editor and also it follows the iCalendar specifications. The generated recurrence rule string is a valid one to be used with the Scheduler event’s recurrence rule field.

There is a ValueChanged event available in recurrence editor, that triggers on every time the fields of recurrence editor tends to change. Within this event argument, you can access the generated recurrence value through the Value option as shown in the following code example.

<div class="recurrence-editor-wrap">
    <div style="padding-bottom: 15px;">
    </div>
    <div>
        <SfRecurrenceEditor Value="@RecurrenceRule" ValueChanged="HandleRecurrenceEditorChange"></SfRecurrenceEditor>
    </div>
</div>

@code {
    string RecurrenceRule { get; set; } = string.Empty;
    async Task HandleRecurrenceEditorChange(string value)
    {
        RecurrenceRule = value;
    }
}

<style>
    .recurrence-editor-wrap {
        margin: 0 25%;
    }
</style>

Set a specific value on recurrence editor

It is possible to display the recurrence editor with specific options loaded initially, based on the rule string that we provide. The fields of recurrence editor will change its values accordingly, when we provide a particular rule through the SetRecurrenceRule method.

@using Syncfusion.Blazor.Schedule
@using Syncfusion.Blazor.DropDowns
    <div class="recurrence-editor-wrap">
        <div class="ddlarea">
            <span class="spanarea">Select Rule</span>
            <div class="ddlcontent">
                <SfDropDownList DataSource="@DropdownData" TValue="string" TItem="DropDownFields" @bind-Value="@RecurrenceValue" PopupHeight="200" PopupWidth="auto">
                    <DropDownListEvents ValueChange="OnRuleChange" TItem="DropDownFields" TValue="string"></DropDownListEvents>
                    <DropDownListFieldSettings Value="Value" Text="Value"></DropDownListFieldSettings>
                </SfDropDownList>
            </div>
        </div>
        <div>
            <SfRecurrenceEditor @ref="RecurrenceEditorRef" Value="@RecurrenceValue"></SfRecurrenceEditor>
        </div>
    </div>
@code {
    SfRecurrenceEditor RecurrenceEditorRef;
    string RecurrenceValue = "FREQ=DAILY;INTERVAL=2;COUNT=8";
    List<DropDownFields> DropdownData = new List<DropDownFields>() {
        new DropDownFields() { Value = "FREQ=DAILY;INTERVAL=1" },
        new DropDownFields() { Value = "FREQ=DAILY;INTERVAL=2;UNTIL=20410606T000000Z" },
        new DropDownFields() { Value = "FREQ=DAILY;INTERVAL=2;COUNT=8" },
        new DropDownFields() { Value = "FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR;INTERVAL=1;UNTIL=20410729T000000Z" },
        new DropDownFields() { Value = "FREQ=MONTHLY;BYDAY=FR;BYSETPOS=2;INTERVAL=1;UNTIL=20410729T000000Z" },
        new DropDownFields() { Value = "FREQ=MONTHLY;BYDAY=FR;BYSETPOS=2;INTERVAL=1" },
        new DropDownFields() { Value = "FREQ=YEARLY;BYDAY=MO;BYSETPOS=-1;INTERVAL=1;COUNT=5" }
    };
    public void OnRuleChange(Syncfusion.Blazor.DropDowns.ChangeEventArgs<string, DropDownFields> args)
    {
        RecurrenceEditorRef.SetRecurrenceRule(args.Value, DateTime.Today);
    }
    public class DropDownFields
    {
        public string Value { get; set; }
    }
}
<style>
    .recurrence-editor-wrap {
        margin: 0 25%;
    }

    .ddlarea {
        padding-bottom: 15px;
    }

    .spanarea {
        font-size: 14px;
    }

    .ddlcontent {
        padding-top: 4px;
    }
</style>

Recurrence date generation

You can parse the RecurrenceRule of an event to generate the date instances on which that particular event is going to occur, using the GetRecurrenceDates method. It generates the dates based on the RecurrenceRule that we provide. The parameters to be provided for GetRecurrenceDates method are as follows.

Field name	Type	Description
startDate	DateTime	Appointment start date.
rule	String	Recurrence rule present in an event object.
excludeDate	String	Date collection (in ISO format) to be excluded. It is optional.
maximumCount	Nullable	Number of date count to be generated. It is optional.
viewDate	Nullable	Current view range’s first date. It is optional.

@using Syncfusion.Blazor.Schedule
@using System.Globalization
    < div class="recurrence-editor-wrap" >
    <div style="padding-bottom: 15px;">
        <label id="rule-label">Date Collections</label>
        <div class="rule-output-container">
            <div id="rule-output">
                @foreach (DateTime date in RecurrenceDates)
                {
                    <div>@date.ToString("ddd MMM dd yyyy HH:mm:ss 'GMT'zzz ('India Standard Time')", CultureInfo.InvariantCulture)</div>
                }
            </div>
        </div>
    </div>
    <div style="display:none">
        <SfRecurrenceEditor @ref="RecurrenceEditorRef"></SfRecurrenceEditor>
    </div >
</div >

@code {
    private SfRecurrenceEditor RecurrenceEditorRef;
    public List < DateTime > RecurrenceDates  = new List < DateTime > ();

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender) {
            await GetRecurrenceDates();
        }
    }

    private async Task GetRecurrenceDates()
    {
        List < DateTime > dates = RecurrenceEditorRef.GetRecurrenceDates(new DateTime(2023, 7, 7, 10, 0, 0), "FREQ=DAILY;INTERVAL=1", "20230708T114224Z,20230710T114224Z", 4);
        RecurrenceDates = dates.ToList();
        StateHasChanged();
    }
}

<style>
    .recurrence-editor-wrap {
        margin: 0 25%;
    }
    .rule-output-container {
        height: auto;
        border: 1px solid #969696;
    }
    #rule-output {
        padding: 8px 4px;
        text-align: center;
        min-height: 20px;
        overflow: hidden;
        overflow-wrap: break-word;
        }
</style>

Above example will generate two dates July 7, 2023 & July 9 2023 by excluding the in between dates July 8 2018 & July 10 2018, since those dates were given in the exclusion list. Generated dates can then be utilised to create appointments.

Recurrence date generation in server-side

It is also possible to generate recurrence date instances from server-side by manually referring the RecurrenceHelper class, which is specifically written and referred from application end to handle this date generation process.

By referring to the RecurrenceHelper class in your sample project, you can make use of the GetRecurrenceDateTimeCollection method which automatically generates the date instances as a result. Below 4 type parameters can be passed to GetRecurrenceDateTimeCollection method.

Type 1: Recurrence rule and start date value (Mandatory parameters).

In this type, we need to pass two mandatory arguments such as recurrence rule and recurrence start date.

var dateCollection = RecurrenceHelper.GetRecurrenceDateTimeCollection("FREQ = WEEKLY; BYDAY = FR,SA; INTERVAL = 1;", DateTime.Now);

Type 2: Maximum number of occurrences to retrieve.

In this type, we can pass the maximum occurrences count (ex: 60) to be retrieved when “Ends Never” option is present in the recurrence. By default, the Ends never maximum count is processed as 43.

var dateCollection = RecurrenceHelper.GetRecurrenceDateTimeCollection("FREQ = WEEKLY; BYDAY = FR,SA; INTERVAL = 1;", DateTime.Now, 60);

Type 3: RecurrenceException.

In this type, we can pass the RecurrenceException date (ex: “20180610T040000Z”) for excluding the dates along with mandatory arguments.

var dateCollection = RecurrenceHelper.GetRecurrenceDateTimeCollection("FREQ = WEEKLY; BYDAY = FR,SA; INTERVAL = 1;", DateTime.Now, "20180610T040000Z,20180602T040000Z");

Type 4: Maximum number of occurrences to retrieve and RecurrenceException.

In this type, we can pass the RecurrenceException for excluding the dates (ex: “20180610T040000Z”) and the maximum occurrence count (ex: 60) for the “Ends Never” option, with the mandatory arguments.

var dateCollection = RecurrenceHelper.GetRecurrenceDateTimeCollection("FREQ = WEEKLY; BYDAY = FR,SA; INTERVAL = 1;", DateTime.Now, "20180610T040000Z,20180602T040000Z", 60);

Restrict date generation with specific count

In case, if the rule is given in “NEVER ENDS” category, then you can mention the maximum count when you actually want to stop the date generation starting from the provided start date. To do so, provide the appropriate maximumCount value within the GetRecurrenceDates method as shown in the following code example.

@using Syncfusion.Blazor.Schedule
@using System.Globalization
    < div class="recurrence-editor-wrap" >
    <div style="padding-bottom: 15px;">
        <label id="rule-label">Date Collections</label>
        <div class="rule-output-container">
            <div id="rule-output">
                @foreach (DateTime date in RecurrenceDates)
                {
                    <div>@date.ToString("ddd MMM dd yyyy HH:mm:ss 'GMT'zzz ('India Standard Time')", CultureInfo.InvariantCulture)</div>
                }
            </div>
        </div>
    </div>
    <div style="display:none">
        <SfRecurrenceEditor @ref="RecurrenceEditorRef"></SfRecurrenceEditor>
    </div >
</div >

@code {
    private SfRecurrenceEditor RecurrenceEditorRef;
    public List < DateTime > RecurrenceDates  = new List < DateTime > ();
    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender) {
            await GetRecurrenceDates();
        }
    }
    private async Task GetRecurrenceDates()
    {
        List < DateTime > dates = RecurrenceEditorRef.GetRecurrenceDates(new DateTime(2023, 7, 7, 10, 0, 0), "FREQ=DAILY;INTERVAL=1", "20230708T114224Z,20230710T114224Z", 10);
        RecurrenceDates = dates.ToList();
        StateHasChanged();
    }
}

<style>
    .recurrence-editor-wrap {
        margin: 0 25%;
    }

    .rule-output-container {
        height: auto;
        border: 1px solid #969696;
    }

    #rule-output {
        padding: 8px 4px;
        text-align: center;
        min-height: 20px;
        overflow: hidden;
        overflow-wrap: break-word;
    }
</style>