Hi,
From your description, I understand that there are two TextBoxes bound to the CalendarExtender. Both of the Calendar should only be selected in the Year/Month mode. The From Calendar has a default date as the first day of selected month. In contrast, the To Calendar has the last day of selected month as the default date.
If I have not misunderstood you, please refer to my sample code about this scenario:
<%@ Page Language="vb" AutoEventWireup="false" CodeBehind="TestOnlyChangeMonthAndSetDefaultDay.aspx.vb"
Inherits="SoluTest_CalendarUserControl.TestOnlyChangeMonthAndSetDefaultDay" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script type="text/javascript">
var cal1;
var cal2;
function pageLoad() {
cal1 = $find("calendar1");
cal2 = $find("calendar2");
modifyCalDelegates(cal1);
modifyCalDelegates(cal2);
}
function modifyCalDelegates(cal) {
//we need to modify the original delegate of the month cell.
cal._cell$delegates = {
mouseover: Function.createDelegate(cal, cal._cell_onmouseover),
mouseout: Function.createDelegate(cal, cal._cell_onmouseout),
click: Function.createDelegate(cal, function(e) {
/// <summary>
/// Handles the click event of a cell
/// </summary>
/// <param name="e" type="Sys.UI.DomEvent">The arguments for the event</param>
e.stopPropagation();
e.preventDefault();
if (!cal._enabled) return;
var target = e.target;
var visibleDate = cal._getEffectiveVisibleDate();
Sys.UI.DomElement.removeCssClass(target.parentNode, "ajax__calendar_hover");
switch (target.mode) {
case "prev":
case "next":
cal._switchMonth(target.date);
break;
case "title":
switch (cal._mode) {
case "days": cal._switchMode("months"); break;
case "months": cal._switchMode("years"); break;
}
break;
case "month":
//if the mode is month, then stop switching to day mode.
if (target.month == visibleDate.getMonth()) {
//this._switchMode("days");
} else {
cal._visibleDate = target.date;
//this._switchMode("days");
}
cal.set_selectedDate(target.date);
cal._switchMonth(target.date);
cal._blur.post(true);
cal.raiseDateSelectionChanged();
break;
case "year":
if (target.date.getFullYear() == visibleDate.getFullYear()) {
cal._switchMode("months");
} else {
cal._visibleDate = target.date;
cal._switchMode("months");
}
break;
// case "day":
// this.set_selectedDate(target.date);
// this._switchMonth(target.date);
// this._blur.post(true);
// this.raiseDateSelectionChanged();
// break;
case "today":
cal.set_selectedDate(target.date);
cal._switchMonth(target.date);
cal._blur.post(true);
cal.raiseDateSelectionChanged();
break;
}
})
}
}
function onCalendarShown(sender, args) {
//set the default mode to month
sender._switchMode("months", true);
changeCellHandlers(cal1);
}
function changeCellHandlers(cal) {
if (cal._monthsBody) {
//remove the old handler of each month body.
for (var i = 0; i < cal._monthsBody.rows.length; i++) {
var row = cal._monthsBody.rows[i];
for (var j = 0; j < row.cells.length; j++) {
$common.removeHandlers(row.cells[j].firstChild, cal._cell$delegates);
}
}
//add the new handler of each month body.
for (var i = 0; i < cal._monthsBody.rows.length; i++) {
var row = cal._monthsBody.rows[i];
for (var j = 0; j < row.cells.length; j++) {
$addHandlers(row.cells[j].firstChild, cal._cell$delegates);
}
}
}
}
function onCalendarHidden(sender, args) {
if (sender.get_selectedDate()) {
if (cal1.get_selectedDate() && cal2.get_selectedDate() && cal1.get_selectedDate() > cal2.get_selectedDate()) {
alert('The "From" Date should smaller than the "To" Date, please reselect!');
sender.show();
return;
}
//get the final date
var finalDate = new Date(sender.get_selectedDate());
var selectedMonth = finalDate.getMonth();
finalDate.setDate(1);
if (sender == cal2) {
// set the calender2's default date as the last day
finalDate.setMonth(selectedMonth + 1);
finalDate = new Date(finalDate - 1);
}
//set the date to the TextBox
sender.get_element().value = finalDate.format(sender._format);
}
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server" />
From :
<asp:TextBox ID="TextBox1" runat="server" AutoCompleteType="Disabled"></asp:TextBox>
<cc1:CalendarExtender ID="CalendarExtender1" BehaviorID="calendar1" runat="server"
Enabled="True" Format="yyyy/MM/dd" TargetControlID="TextBox1" OnClientShown="onCalendarShown"
OnClientHidden="onCalendarHidden">
</cc1:CalendarExtender>
To :
<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
<cc1:CalendarExtender ID="CalendarExtender2" BehaviorID="calendar2" runat="server"
Enabled="True" Format="yyyy/MM/dd" TargetControlID="TextBox2" OnClientShown="onCalendarShown"
OnClientHidden="onCalendarHidden">
</cc1:CalendarExtender>
</div>
</form>
</body>
</html>
Have my code helped? Here is another thread which is similar to yours:
http://forums.asp.net/t/1342938.aspx.
Best regards,
Zhi-Qiang Ni