How can I not default a date in DropDownDatePicker

Hi

I have a data entry window where I have several DropDownDatePicker.  My problem is that I do not want a date to appear if the use has not entered a date.  Is it possible not to display a default date?

Thanks

Unfortunately we do not have this feature at the moment (because we do not have the concept of an "undefined" date).  Sorry.

Hi Ivan,

Would you happen to have any try of work around.

 Thanks

I don't have anything that I have tested or can provide as a sample, but the way I would tackle this would be something like this:

1. Create a user control or custom control with a Date property of type Nullable<DateTime> (or however you want to model the "undefined" date).

2. In the template, create two "views" and overlay them (e.g. create a 1-cell Grid and put both of them in the same cell):

  2a.  The first is a normal DropDownDateTimePicker.

  2b.  The second is a custom UI for "no date selected."  For simplicity, let's say this is a button that says "Select date," though you could design something nicer, e.g. a label+button combination that looked like an empty DropDownDateTimePicker.  Set the Visibility of this view to Collapsed.

3. Use triggers to specify that if the Date is null, the first view's Visibility is Collapsed and the second view's Visibility is Visible.

4. Hook up an event handler or command so that when the user clicks on the "select date" button, it sets the Date property to a suitable default (causing the control to switch to the first view), and opens the drop-down.

You may want to consider whether the first view should also have a "delete date" button to reset the Date property to null.

Hope this helps -- let us know if you need any help with this or run into any problems. 

Thanks Ivan,

I will give this a try.

FWIW, Ivan's approach works nicely and is pretty simple.  Here's the basics of the datatemplate:

<DataTemplate x:Key="DateTimeEditor">

<Grid>

<Button Visibility="Collapsed" Content="Select date..." Name="btnSelectDate" Click="btnSelectDate_Click" ></Button>

<Grid Name="gridSelectDate" Visibility="Visible" HorizontalAlignment="Stretch" Background="Blue">

<Grid.ColumnDefinitions>

<ColumnDefinition Width="*"/>

<ColumnDefinition Width="Auto" />

</Grid.ColumnDefinitions>

<mse:DropDownDatePicker Grid.Column="0"Format="Custom" CustomFormat="{Binding Path=CustomDateFormatString, ElementName=ctlPropertyEditor, Mode=Default}" Value="{Binding DateTimeValue, Mode=TwoWay}" />

<Button Grid.Column="1" Content="Clear" Name="btnClear" IsEnabled="{Binding IsEnabled}" Click="btnClear_Click" ></Button>

</Grid>

</Grid>

<DataTemplate.Triggers>

<DataTrigger Value="True" Binding="{Binding DateTimeValue, Converter={StaticResource IsDateTimeNullConverter}}">

<Setter TargetName="btnSelectDate" Property="Visibility" Value="Visible"/>

<Setter TargetName="gridSelectDate" Property="Visibility" Value="Collapsed" />

</DataTrigger>

<DataTrigger Value="False" Binding="{Binding DateTimeValue, Converter={StaticResource IsDateTimeNullConverter}}">

<Setter TargetName="btnSelectDate" Property="Visibility" Value="Collapsed"/>

<Setter TargetName="gridSelectDate" Property="Visibility" Value="Visible" />

</DataTrigger>

</DataTemplate.Triggers>

</DataTemplate>

Here is the converter that I used (in my app 1/1/1800 is a null date):

Implements IValueConverter

Try

If datVal.Year = 1800 Then

Return True

Else

Return False

End If

Return True

End Try

End Function

End Function

End Class

And here are the event handlers for my buttons:

Dim dtObject = TryCast(DirectCast(sender, Button).DataContext, DateTimePropertyObject)

If Not dtObject Is Nothing Then

End If

End Sub

Dim dtObject = TryCast(DirectCast(sender, Button).DataContext, DateTimePropertyObject)

If Not dtObject Is Nothing Then

End If

End Sub

Hope this is helpful!

Sean