c# - 指定的转换对日期选择器无效

Question

我尝试在选择器中评估日期之前检查 null，因为我不允许输入任何日期:

 <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>

---

但我一直收到以下错误:

Specified cast is not valid.

Answer 1

我相信您应该使用 DbSelectedDate 属性来绑定(bind)值而不是 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, i.e. the input value will be empty.

From here