I've found it difficult to follow the example, but I'll offer two general
observations in the hope that they may be of some use.
First, if you need to keep track of changes to a control value across the
various events that are fired when a control value changes, and OldValue
doesn't meet your requirements, consider storing the values yourself in
module-level variables.
Second, I have, unfortunately, found the form and control undo event
procedures to be useless for all the purposes for which I might want to
use
them, because they are single events that fire (if I remember correctly)
after the undo operation is complete. What we need is Before Undo and
After
Undo events, in the same way that we have Before Update and After Update
events. In the absence of these, I often find myself forced to resort to
the
Timer event to ensure that controls are enabled or disabled when they
should
be.
--
Brendan Reynolds (MVP)
http://brenreyn.blogspot.com
The spammers and script-kiddies have succeeded in making it impossible
for
me to use a real e-mail address in public newsgroups. E-mail replies to
this post will be deleted without being read. Any e-mail claiming to be
from brenreyn at indigo dot ie that is not digitally signed by me with a
GlobalSign digital certificate is a forgery and should be deleted without
being read. Follow-up questions should in general be posted to the
newsgroup, but if you have a good reason to send me e-mail, you'll find
a useable e-mail address at the URL above.
Here is perhaps a better example. I have a combo box called Status
having
RowSource ValueList including "Open";"Closed".
Status_AfterUpdate calls SetControls. The germane portion of
SetControls
is:
If Status = "Closed" Then
[Several lines here to disable all other controls)
Else
[Several lines here to enable all other controls)
End If
When user picks "Closed" from Status, Status_AfterUpdate fires, and all
other controls are disabled by SetControls. The user now, without
moving
to
another control, presses ESC. Status is now "Open", but all other
controls
remain disabled. If user types "Closed" rather than picking it from
dropdown
list, then Status_AfterUpdate does not fire until Status_Exit, so the
problem
does not exist in the same way.
I thought I could resolve this with Form_Undo, but here again, the
OldValues
are still in place. The root question is how to call SetControls after
a
particular control or the entire form reverts to OldValue.
For a workaround, I enabled Form.KeyPreview and call SetControls if
KeyPress
is ESC. This works except when user presses ESC while in one of the
controls
that gets disabled by SetControls, so I move the focus to a known
enabled
control before running SetControls. This, in turn, causes a error
(Can't
move
focus...) when I drop down any combo box, begin typing the entry, and
then
press ESC.
Thanks.
:
You could try using the Exit event of the controls to run the code. At
that
point, your control's value will be whatever is to remain in the
control
when the person leaves the control.
--
Ken Snell
<MS ACCESS MVP>
Access 2002 SP3
I have a Sub called SetControls that I call in Form_Current
AfterUpdate
of
several controls. It enables/disables certain controls based on the
value
of
other controls. For instance, here is an excerpt of that Sub that
disables
the BuyerContract field until the Buyer is entered:
If IsNull (Buyer) Then
BuyerContract.Enabled = False
Else
BuyerContract.Enabled = True
End If
The problem is getting this to fire when Buyer is undone. I cannot
use
Buyer.OldValue because I may call this from many places in the
module
when
Buyer has no OldValue. Since I first posted, I think I found a
better
solution.
I tried calling my Sub from Form_Undo. However, the value of Buyer
is
still
its OldValue at the time Form_Undo fires. Furthermore, I need to
ensure
that
the focus moves away from BuyerContract before it is disabled, which
would
generate an error.
I finally resorted to turning on KeyPreview for the form and running
this:
Private Sub Form_KeyPress(KeyAscii As Integer)
If KeyAscii = 27 Then 'user presses ESC
Status.SetFocus 'moves the focus off a control that may be
disabled
in
next step
SetControls
End If
End Sub
Better ideas?
Thanks.
:
How does that Sub know what the value of the control is, regardless
of
whether it's the original or current value? You'll need to tell us
more
info... I'm not convinced yet that you cannot use the OldValue
value,
especially if you pass the control object as an argument to the
subroutine
itself.
Which version of ACCESS are you using?
--
Ken Snell
<MS ACCESS MVP>
How can I get an event to fire after the undo of a control?
I need to use the original value of the control in running
another
Sub
after
undoing the control, but the value does not revert until after
the
Undo
event
is complete. I cannot simply use the ControlName.OldValue because
I
run
the
same Sub (using the reference to this and other control names) in
several
other places in this module.
