Binding Date Only and Time Only

Question

I have 2 controls:

DatePicker: For Date Only
TextBox with TimeMask: For Time Only

They are both linked to the same property DateTime EffectiveDate But the problem is when I change the Date on the DatePicker, it changes the Time in the TimeTextBox back to 12:00.

I understand the reason for it, but what best solution is out there to let these work separately but bound to the same property?

I have tried to take the current time and build a new Date in the set property but always end up with overflow errors.

Answer 1

You can use a value converter to hold on to the value

public class DateConverter : IValueConverter
{
    private DateTime timePickerDate;

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        timePickerDate = ((DateTime)(value));

        return value;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value == null) return timePickerDate;

        var datePickerDate = ((DateTime)(value));

        // compare relevant parts manually
        if (datePickerDate.Hour != timePickerDate.Hour
            || datePickerDate.Minute != timePickerDate.Minute
            || datePickerDate.Second != timePickerDate.Second)
        {
            // correct the date picker value
            var result = new DateTime(datePickerDate.Year,
                 datePickerDate.Month,
                 datePickerDate.Day,
                 timePickerDate.Hour,
                 timePickerDate.Minute,
                 timePickerDate.Second);

            // return, because this event handler will be executed a second time
            return result;
        }

        return datePickerDate;
    }
}

And have the two controls in question bind to the one property but have the date picker use the converter to not override the time.

<Grid Margin="10,5" >        
    <Grid.ColumnDefinitions>
        <ColumnDefinition/>
        <ColumnDefinition Width="auto"/>
    </Grid.ColumnDefinitions>
    <sdk:DatePicker Grid.Column="0" TabIndex="1" Padding="0" SelectedDate="{Binding EffectiveDate, Mode=TwoWay, Converter={StaticResource DateConverter}}" SelectedDateFormat="Short"/>
    <toolkit:TimePicker Grid.Column="1" Value="{Binding EffectiveDate, Mode=TwoWay}" Margin="0" Padding="0" HorizontalAlignment="Left" TabIndex="2" />
</Grid>

Answer 2

You could do something like this:

private DateTime _effectiveDate;
...
public DateTime DateOfEffectiveDate
{
    get { return _effectiveDate; }
    set
    {
        _effectiveDate = new DateTime(value.Year, value.Month, value.Day, _effectiveDate.Hour, _effectiveDate.Minute, _effectiveDate.Second);
    }
}

public DateTime TimeOfEffectiveDate
{
    get { return _effectiveDate; }
    set
    {
        _effectiveDate = new DateTime(_effectiveDate.Year, _effectiveDate.Month, _effectiveDate.Day, value.Hour, value.Minute, value.Second);
    }
}

Answer 3

The built-in DatePicker control selects only a date without any specific time so I am afraid it makes no sense to try to display the time of the selected date in a TextBox. The DatePicker will effectively clear out the time part each time a new date is selected. This is how the control works.

So you should bind the DatePicker and the TextBox to two different source properties, a DateTime? and a TimeSpan respectively.

The other option would be to use another control that selects a date and a time, for example this one: http://wpftoolkit.codeplex.com/wikipage?title=DateTimePicker