Hi Mike,

 I kept getting the error " value cannot be set outside the range of the min/max value . . ." something like that.  I found the problem was comming from the fact that the application is using business object class, where a null datetime property will carry a value of  "1/1/001 12:00:00 AM" which, if I am not mistaken,  is different the Infragistics minimum value for this datatype,

Anyway, I corrected the problem by putting a check for Year on in the code that loads the data into form controls.

If myClass.RevisionDate.Date.Year = 1 Then

   myDateControl.Value=Nothing

Else

   myDateControl.Value= MyClass.RevisionDate

End If

I could have put the code in the Class property declaration itself, but then the class cause problems elsewhere accross the solution.

Regards,

Rob

Well, I thought I had it beat.

Turn out, after trying to implement data bindings on the business class object, problems re-emerged.  To correct, I had to implement corrective code in the class date property constructor as follows. . .

Private _RevisionDate as Date

Public Property RevisionDate() as Date
Get
 If _RevisionDate.Year=1 Then
  Return CDate(“1/1/1753”)
 Else
  Return _RevisionDate
 End IF
End Get
Set(ByVal value as Date)
 If value = CDate(“1/1/1753”) Then value = Nothing
 _RevisionDate = value
End Set
End Property

Then, after setting the form data bindings on the controls to the business class object, I still had to force a Null value into the date control, like . . .

If CType(Me.RevisionDate.Value, Date) = CType("1/1/1753 12:00:00 AM", Date) Then _
Me.RevisionDate.Value = Nothing

And the control is still not correct, as it does not allow the user to enter and then leave without setting a valid date value.  So am I missing something here?

Regards,
Rob

Hi Rob,  

    It sounds to me like the problem is your data source, not the DateTimeEditor. As I said, a DateTime variable in DotNet cannot hold a null value. It's a struct. 1/1/0001 is the minimum date, but it's not the same as a null. If you need to store DBNull or Null in your data source, then it needs to be n object type. Or else you will need to use a DataFilter to convert the null into MinDate and vice versa.

Mike,

Yes, I understand the struct, and that a variable declared as a DateTime data type carries a minimum value (1/1/0001) and not a DBNull per say, in much the same way that an Integer data type carries a default value of 0 (can’t say minimum because of negative numbers etc).  The data source I am using is a simple class object, whose property declarations should be treated like any other sort of strongly typed data source.

What a control renders to the display is the result of whatever intelligence programmed into its Paint method.  Looking at the Infragistics DateTime Editor, we see that it has a Null Text Property, that will cause such text to be displayed in the control whenever the Value Property is equal to Nothing.

And allow me to give Kudos for extending the Null Text property to your controls.  A handy little feature that saves me from having to clutter forms with Labels.  Something I been hoping to see in controls for a long time.

Now sure enough, when Nothing is passed to the Value of the DateTime Editor, a custom, non-date, character string is displayed in the control (Ta Daaa !).

Great.  So I guess my question is,  Is it too much to ask for the control to be smart enough to say “when the input to the Value property is less then a specified minimum date or Nothing, then display the NullText value or nothing, as the case may be.  I believe that would make many people very happy.

Which brings me back to the original question.  What is the purpose of the Nullable Property on the control?  I can’t seem to get the control to manage Null/Nothing values very well.

Anyway, I picked up on your hint regarding an Object data type and added another property constructor to the class of that type, and bound your control to it, and now it appears to have the desired behavior.  The pseudo property declaration looks like this:

Public Property IIssueDate() As Object
  Get
    If _IssueDate.Year = 1 Or _IssueDate.Year = 1753 Then
      Return Nothing
    Else
      Return _IssueDate
    End If
  End Get
  Set(ByVal value As Object)
    If CType(value, Date) = CDate("1/1/1753") Then value = CType("1/1/0001", Date)
       _IssueDate = CType(value, Date)
    End Set
End Property

Regards,
Rob

Hey Mike,

Ya know this is something that has been bugging me for ages.  I am sure that it is quite common across many business process solutions, that there are requirements to have optional Date.  For example, Project StartDate, ProjectEnd.  A future date can always be entered into the StartDate if the process has yet to begin, but while the process is ongoing, we cannot have a value EndDate.  Oddly enough, SQL Server has no problem handling this situation (ie passing null/nothing values to parameters with a Date data type).

This being the case, any Date Control aught to be able to handle whatever is considered to be a Null Date.  In the .Net world, this value is 1/1/0001.  Therefore, that portion of my Validation Layer that handles Date values, as well as the Data Access Layer that will pass such values to the database via ADO, have both been coded with respect to the Year 1 value.  So everything is right, until I am compelled to use a date control on a front end.  That’s the problem.

I think the Min/Max properties are right for Business Logic. preventing the user for entering a value that is outside a desired range.  However, there must be some value that the control considers to be a Null Date, if not Year 1, then some other value assigned by the user.  That would solve the problem quite nicely.

Regards,
Rob

ps

It’s true, I could write the corrective code around the DataBinding Class, or in any of the Filters that you mentioned.  However, I didn't want to write code every where, so doing it in the business class objects seemed the right thing to do.  Do it there also corrected the display issue I was having with ultra grid columns that carried a grid column style of DateTime, which were also showing the Year 1 value instead of nothing.

I will post a link to this thread in a Feature Request

r.