Hi there,

I have a perentform which contains a datagridview to present and seek customer-data

and use a childformdialog to open a child-window to edit a selected record.

This is the code in my parent-form

Dim cErr As String = ""

Me.KundenBO1.Edit()

If Me.ChildKundNeu.ShowDialog(False, Me) = DialogResult.OK Then

If KundenBO1.Save <> MicroFour.StrataFrame.Data.SaveUndoResult.Success Then

cErr = "Fehler beim Speichern!"

mymsgbox(cErr, 48, cProgtitle)

Else

cErr = "Satz gespeichert!"

mymsgbox(cErr, 64, cProgtitle)

End If

Else

cErr = "Abbruch"

Me.KundenBO1.Undo(MicroFour.StrataFrame.Business.BusinessUndoType.CurrentRowOnly)

mymsgbox(cErr, 64, cProgtitle)

End If

So far, so good. The first parameter in the constructor determines, if a record ist added (True) or edited (False). Now whe I edit a record I want enable the use to undo changes in the child-form without closing and opening it again. So I put an "Undo-Button" on the form and call the Undo-Method of the childform-BO which is set up in the BO-Translations of the childformdialog as the destination BO.

KundenBO1.Undo(MicroFour.StrataFrame.Business.BusinessUndoType.CurrentRowOnly)

But this leads to the following error (Translated from german):

"Invalid conversion from type DBNull to type string"

And this is where it happens:

Public Overrides Sub SetValue(ByVal component As Object, ByVal value As Object)

Select Case Me.Field

Case KundenBOFieldNames.KUNDENNR

DirectCast(component, KundenBO).KUNDENNR = CType(value, System.Int32)

Case KundenBOFieldNames.ANREDE

DirectCast(component, KundenBO).ANREDE = CType(value, System.String)

The last Directcast is where the error happens.

I wonxder now if I am doing something wrong or if this can not be done this way.

Thanks for your help

Thomas