Undo problem

[Waubain]

I have a subform(wihtin a main form) that opens in read only. There is a EDIT button that opens separate formr to edit the subform records. On this second form there is a Cancel button that will undo any changes and closes the form. This is the basic code for the Cancel button.

Private Sub Command46_Click()
' Undo the changes
DoCmd.RunCommand acCmdUndo
' Close the form
DoCmd.Close acForm, Me.Name
End Sub

The problem is that if a person clicks the Cancel button before any changes are made then they get an error(2046, Undo isn't available now), probably because there is nothing to undo. I would like to undo and close if changes were made, or close if no changes made.



I know I need some type of error trapping, but would appreciate any help.

[boblarson]

How about going to this instead:

Private Sub Command46_Click()
' Undo the changes
If Me.Dirty Then
   Me.Undo
End If
' Close the form
DoCmd.Close acForm, Me.Name
End Sub

[Waubain]

This works great. Thank you.

Just as there are many ways to complete a task in VBA, there is probably not a single correct answer to this question. As a novice it is unclear if there is a "best practice" in solving a task? In my first attempt at creating the Cancel(Undo) button I used this statement I found on the web.

DoCmd.RunCommand acCmdUndo

In your reply this worked just as well (within the IF statement).

Me.Undo

Short and direct. My philosophy in most cases is the least complex answer is usually the best. Many how-to books are written but few address why ,in general, one command might be better than another.

Thank you again.

[boblarson]

The DoCmd commands can be helpful but, as you have mentioned, sometimes there are better ways (or at least more direct ways) to accomplish the same thing.

Using Me.Undo instead is more specific than using the RunCommand as it may be possible for the form to lose focus for some reason and the DoCmd.RunCommands deal with the active object at the time. So, by using Me.Undo instead, you have now made it more specific to that specific form and it will work on that specific form regardless of what has the focus.

[Waubain]

Thank you for the explanation.