NavigationControl.OldValue Property (Access)
You can use the OldValue property to determine the unedited value of a bound control. Read-only Variant.
The OldValue property contains the unedited data from a bound control and is read-only in all views.
Microsoft Access uses the OldValue property to store the original value of a bound control. When you edit a bound control on a form, your changes aren't saved until you move to another record. The OldValue property contains the unedited version of the underlying data.
You can provide your own undo capability by assigning the OldValue property setting to a control. The following example shows how you can undo any changes to text box controls on a form:
Private Sub btnUndo_Click() Dim ctlTextbox As Control For Each ctlTextbox in Me.Controls If ctlTextbox.ControlType = acTextBox Then ctlTextbox.Value = ctl.OldValue End If Next ctlTextbox End Sub
If the control hasn't been edited, this code has no effect. When you move to another record, the record source is updated, so the current value and the OldValue property will be the same.
The OldValue property setting has the same data type as the field to which the control is bound.
The following example checks to determine if new data entered in a field is within 10 percent of the value of the original data. If the change is greater than 10 percent, the OldValue property is used to restore the original value. This procedure could be called from the BeforeUpdate event of the control that contains data you want to validate.
Public Sub Validate_Field() Dim curNewValue As Currency Dim curOriginalValue As Currency Dim curChange As Currency Dim strMsg As String curNewValue = Forms!Products!UnitPrice curOriginalValue = Forms!Products!UnitPrice.OldValue curChange = Abs(curNewValue - curOriginalValue) If curChange > (curOriginalValue * .1) Then strMsg = "Change is more than 10% of original unit price. " _ & "Restoring original unit price." MsgBox strMsg, vbExclamation, "Invalid change." Forms!Products!UnitPrice = curOriginalValue End If End Sub