Hide a control (Access 2K)

[jordanf]

I would like to have a control on a form (command button) change its visibility depending on a value in a text field in that record. Specifically, if a RegNumb has not been assigned to a record, then I want a command button to appear that will increment the maximum value of RegNumb in the table by 1 and assign it to that record. I have the button that does the incrementing working with this code

Private Sub cmdRegNumb_Click()
[RegNumb] = (txtMaxRegNumb) + 1
End Sub

but I want to change its visibility with something like this:

If ([RegNumb] = Null) Then
cmdRegNumb.Visible = True
Else
cmdRegNumb.Visible = False
End If


Is this a possible thing to do?

[DaleNapier]

Yes it is possible, and the approach you suggest should work fine. Have you tried it?

[HansV]

You cannot use = Null in a comparison, for Null is not really a value, it indicates the lack of a value. Instead, use the IsNull function:

If IsNull(Me.RegNumb) Then
Me.cmdRegNumb).Visible = True
Else
Me.cmdRegNumb.Visible = False
End If

This can be simplified to

Me.cmdRegNumb.Visible = IsNull(Me.RegNumb)

You can use this code in the On Current event of the form, so that the visibility of the button is kept correct as the user moves from record to record. It is also a good idea to check whether the command button has the focus, and change the focus if so, for you cannot hide a control that has the focus:

Private Sub Form_Current()
If Screen.ActiveControl.Name = "cmdRegNumb" Then
Me.SomeOtherControl.SetFocus
End If
Me.cmdRegNumb.Visible = IsNull(Me.RegNumb)
End Sub

Note: personally, I would use the Enabled property of the command button instead of the Visible property, but that is a matter of taste.

[jordanf]

Hans,

Thanks, that took care of my problem. Appreciate the rapid response.