How do I prevent control passing to the next Userform textbox? - vba

Question

I have a Userform with multiple Textboxes. All the Textboxes are in tab-order.
Each subsequent Textbox is back colored yellow to indicate to the user which is the next Textbox to complete.
If the Textbox Value is determined to be invalid I want the control to SetFocus back on that particular Textbox. However, control is automatically handed over to the next Textbox in the tab-order.
When I try to focus back on the required Textbox with the mouse, this fires an event on the next Textbox, which follows the rules of my program and requests the user to enter a valid value.
Below is a sample of two Textboxes, if the user fails to enter a first name I want the control to return to the tbxCustomerFirstName Textbox, however, the control is handed over to the tbxCustomerSurName Textbox, even though I've "tbxCustomerFirstName.SetFocus".
AstFlag = 2 means there has to be a valid value in the Textbox.
AstFlag = 1 means the Textbox value can be blank.
I stepped through the program and AstFlag does indeed = 2, and the set focus code is executed.
'====================================================================================
'
' Customer First Name
'
Private Sub tbxCustomerFirstName_Exit(ByVal Cancel As MSForms.ReturnBoolean)
Call tbxValues(3)
If tbxCancel = True Then
Cancel = True
End If
If AstFlag = 2 Then
tbxCustomerFirstName.SetFocus
End If
End Sub
'====================================================================================
'
' Customer Surname
'
Private Sub tbxCustomerSurName_Exit(ByVal Cancel As MSForms.ReturnBoolean)
Call tbxValues(4)
If tbxCancel = True Then
Cancel = True
End If
If AstFlag = 2 Then
tbxCustomerSurName.SetFocus
End If
End Sub

Answer 1

You want to set the Cancel parameter to True when you mean to cancel exiting the control.
I don't know what your tbxCancel flag logic is, but...
If AstFlag = 2 Then
theControlYouAreExiting.SetFocus
End If
Should be
If AstFlag = 2 Then
Cancel.Value = True
End If
That will prevent exiting the control, so there's no need to SetFocus on anything. Now again I don't know what tbxCancel is supposed to be doing, but it doesn't look right.
In fact I would scrap all this painfully duplicated conditional logic, and implement some Validate method that returns True if the field is valid (and thus can be exited) and False if the field is invalid (and thus Cancel.Value must be True and focus remains on the control).
Cancel.Value = Not Validate(args)
Where args could be theControlYouAreExiting.Tag, and then you could use the controls' Tag property to hold the metadata you're likely currently hard-coding in tbxValues.
Ultimately the problem you're solving is going to create a mess no matter how you put it, because everything is happening in the form's code-behind: you want to separate the View (the form/UI) from the Model (the data it's manipulating).
The solution is to create a class module that represents your model. This model exposes a property that each control on your form manipulates, and then the model itself knows how to validate each property.
Option Explicit
Private model As CustomerModel
Private Sub UserForm_Initialize()
Set model = New CustomerModel
End Sub
Public Property Get CustomerModel() As CustomerModel
Set CustomerModel = model
End Property
Public Property Set CustomerModel(ByVal value As CustomerModel)
Set model = value
End Property
Private Sub tbxCustomerSurName_Change()
model.Surname = tbxCustomerSurName.Text
End Sub
Private Sub tbxCustomerSurName_Exit(ByVal Cancel As MSForms.ReturnBoolean)
Cancel.Value = Not model.IsValidSurname
End Sub
And with that you don't need to maintain flags and state switches to keep track of what the metadata is for the control you're in.