Question

I have a DataGrid that has as one of its columns a DatePicker (for the editing template). Is there a way to keep this but still allow a user to enter in a NULL date?

Answer 1

Do the following (in Silverlight 4):

1) Bound property of DataContext must be Nullable (or Datetime?)

2) In XAML set TargetNullValue= of binding property something like:

Text="{Binding DocumentDate, Mode=TwoWay, StringFormat= yyyy-MM-dd , TargetNullValue=  }"

Answer 2

Found this while researching same problem. This is how I fixed it since it hasn t been marked.

I have used converter which converts value to null if it is just an empty datatime object.

public class DateTimeToNullConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            DateTime dt = new DateTime(); 
            if (dt.Equals(value)) return null; 
            return value;
        } 
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) 
        { 
            return value; 
        }
    }

XAML:

SelectedValue="{Binding CurrentContractRenewal.ExpiryDate, Mode=TwoWay, Converter={StaticResource DateTimeToNullConverter}}"

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