Question

I have a windows phone 7 application where I´m using a “DatePicker” from the silverlight toolbox.

I´m trying to save the choosen DatePicker value, as suggestion I assign it to an DateTime structure so that I later can populate the same DatePicker with the saved DateTime value. Simple as it sounds, I don´t get it to work due to an error:

Cannot implicitly convert type ‘System.DateTime?’ to ‘System.DateTime’. An explicit conversion exists (are you missing a cast?)

when constructing the DateTime value as below:

DateTime saved = datePicker.Value;

The DateTime are to be saved for later use as following:

datePicker.Value = saved.Value;

Does the DatePicker not have a valid DateTime value? I´m new at this, what shall I do?

Answer 1

The Datepicker Value property is a Nullable<DateTime> (same as DateTime?). This is so it can represent “nothing chosen”. (DateTime is a struct, so it can not be null). Can you store a Nullable<DateTime> instead? Otherwise, you can test if the Nullable<DateTime> has a value:

if (datePicker.Value.HasValue)
{
    //save
    DateTime saved = datePicker.Value.Value;
}