Dynamically add CalendarExtender to Textbox subclass server control? - asp.net

Question

I'm trying to create a server control, which inherits from TextBox, that will automatically have a CalendarExtender attached to it. Is it possible to do this, or does my new control need to inherit from CompositeControl instead? I've tried the former, but I'm not clear during which part of the control lifecycle I should create the new instance of the CalendarExtender, and what controls collection I should add it to. I don't seem to be able to add it to the Page or Form's controls collection, and if I add it to the (TextBox) control's collection, I get none of the pop-up calendar functionality.

Answer 1

I accomplished this in a project a while back. To do it I created a CompositeControl that contains both the TextBox and the CalendarExtender.
In the CreateChildControls method of the CompositeControl I use code similar to this:
TextBox textbox = new TextBox();
textbox.ID = this.ID + "Textbox";
textbox.Text = this.EditableField.TextValue;
textbox.TextChanged += new EventHandler(HandleTextboxTextChanged);
textbox.Width = new Unit(100, UnitType.Pixel);
CalendarExtender calExender = new CalendarExtender();
calExender.PopupButtonID = "Image1";
calExender.TargetControlID = textbox.ID;
this.Controls.Add(textbox);
this.Controls.Add(calExender);
Of course make sure that the form containing this CompositeControl has a toolkit script manager.

Answer 2

I know this is an old thread, but I came across it when I had a similar question. This is what I ended up implementing, and it works great. If you want the control to BE a TextBox, then simply pump out the extender during the call to Render.
Imports System.Web.UI.WebControls
Imports AjaxControlToolkit
Public Class DateTextBox
Inherits TextBox
Private _dateValidator As CompareValidator
Private _calendarExtender As CalendarExtender
Protected Overrides Sub OnInit(ByVal e As System.EventArgs)
MyBase.OnInit(e)
_dateValidator = New CompareValidator
With _dateValidator
.ControlToValidate = ID
Rem set your other properties
End With
Controls.Add(_dateValidator)
_calendarExtender = New CalendarExtender
With _calendarExtender
.TargetControlID = ID
End With
Controls.Add(_calendarExtender)
End Sub
Protected Overrides Sub Render(ByVal writer As System.Web.UI.HtmlTextWriter)
MyBase.Render(writer)
_dateValidator.RenderControl(writer)
_calendarExtender.RenderControl(writer)
End Sub
End Class

Answer 3

You can easily add ajax calendar in custom server controls. You need to add two reference in your application.
1. AjaxControlToolkit.dll
2. System.Web.Extensions
With the help of second reference we will get all the property of “CalendarExtender” in your custom server controls.

Answer 4

When you are trying to not allow users to type anything in the textbox, but only be filled by the calendar extender and then you try to get the selected date from the textbox control it may be empty string if you have set the textbox property to ReadOnly="True".
Its because read only controls are NOT posted back to the server. Workaround for this is the following:
protected void Page_Load(object sender, EventArgs e)
{
TextBox1.Attributes.Add("readonly", "readonly");
}
Hope it helps.