Specified cast is not valid for the date picker

Question

I try to check null before evaluate the date in my picker because i allow to enter no date :

 <telerik:RadDatePicker ID="rpick_to_date" runat="server" Visible="false" SelectedDate='<%# Eval("to_date") == null ? "" : Eval("to_date") %>'>
                                            <Calendar UseColumnHeadersAsSelectors="False" UseRowHeadersAsSelectors="False" ViewSelectorText="x">
                                            </Calendar>
                                            <DatePopupButton HoverImageUrl="" ImageUrl="" />
                                            <DateInput DateFormat="dd/MM/yyyy" DisplayDateFormat="dd/MM/yyyy">
                                            </DateInput>
 </telerik:RadDatePicker>

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but i get the following error all the time :

Specified cast is not valid.

Answer 1

I believe you should be using DbSelectedDate property to bind the value instead of SelectedDate

Use the DbSelectedDate property than SelectedDate to get or set the date content of RadDatePicker in a database friendly way. The only difference with SelectedDate is that it will not throw an exception if the new value is null or DBNull. Setting a null value will internally revert the SelectedDate to the null value, ie the input value will be empty.

From here

Answer 2

您可以使用此代码（删除字符串“”） SelectedDate为Nullable<DateTime>

SelectedDate='<%# Eval("to_date")%>'