Set Default Time to RadDateTimePicker

Description

Generally, you can select an initial date and time for the picker control using its SelectedDate property. However, if you want the control to be empty until the user selects a date, when a date is actually selected, the time will be automatically set to 12:00 AM midnight. 

Solution

In order to configure the control to set your predefined time automatically when a date is selected, you can use the following approach:

ASP.NET

<telerik:RadDateTimePicker runat="server" ID="RadDateTimePicker1">
    <TimeView runat="server" StartTime="08:00" EndTime="20:00"
        OnClientTimeSelecting="timeSelecting" />
    <ClientEvents OnDateSelected="dateSelected" />
    <DateInput runat="server">
        <ClientEvents OnValueChanging="valueChanging" />
    </DateInput>
</telerik:RadDateTimePicker>

JavaScript

<script type="text/javascript">
    // using a variable to prevent infinite loop
    var isTimeSet = false;
    function timeSelecting(sender, args) {
        isTimeSet = true;
    }
    function dateSelected(sender, args) {
        if (args.get_newDate() && !isTimeSet) {
            args.set_cancel(true);
            isTimeSet = true;
            sender.get_timeView().setTime(8, 0, 0, 0);
        }
        if (isTimeSet) {
            isTimeSet = false;
        }
    }
    function valueChanging(sender, args) {
        if (args.get_newValue().indexOf(":") > 0) {
            isTimeSet = true;
        }
    }
</script>