Q189923: PRB: No Validate Event When Activating CommandButton

Article: Q189923
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:6.0
Operating System(s): 
Keyword(s): kbGrpDSVB
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, version 6.0 
- Microsoft Visual Basic Professional Edition for Windows, version 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 
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SYMPTOMS
========

On a form in Visual Basic, you have a CommandButton whose CausesValidation
property is True. Also, the CommandButton's Default or Cancel properties are
True. The Default and Cancel properties allow you to activate the CommandButton
by pressing the ENTER or ESC keys. When you activate the CommandButton by
pressing ENTER or ESC, the Validate event for the current control does not occur
and the Click event of the CommandButton fires. This may cause undesirable
results if you need the Validate event for the current control to occur before
the Click event of the CommandButton.

If you activate the CommandButton using the mouse or the CommandButton's
accelerator key, the Validate event for the current control occurs as expected.

CAUSE
=====

When you activate a "default" or "cancel" CommandButton by pressing the ENTER or
ESC keys, focus does not change to the CommandButton. Because Focus remains in
the current control, the Validate event for the current control does not occur.
In short, the CausesValidation property for a Default or Cancel CommandButton is
ignored when you activate the CommandButton by pressing the ENTER or ESC keys.

RESOLUTION
==========

To work around this limitation when using Default or Cancel CommandButtons, you
must add your validation code to the Click event of the CommandButton.

STATUS
======

This behavior is by design.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Start a new Standard EXE project in Visual Basic. Form1 is created by
  default.

2. Add a TextBox control.

3. Add a CommandButton control.

4. Set the following properties of Command1:

        Caption = Command&1
        Cancel = True
        CausesValidation = True
        Default = True

5. Add the following code to the Form1 module:

        Option Explicit

        Private Sub Text1_Validate(Cancel As Boolean)
           ' Ensure Text1 has data else keep focus in Text1:
           If Trim(Text1.Text) = "" Then Cancel = True
        End Sub

        Private Sub Command1_Click()
           Unload Me
        End Sub

        Private Sub Form_Load()
           Text1.Text = ""
        End Sub

6. Run the project. Text1 has focus and is empty.

7. Click Command1 or press the ALT+1 key combination. The Validate event occurs
  for Text1 as Expected. Because Text1 is empty, the Validate event keeps focus
  in Text1 and prevents the CommandButton from closing the form.

8. With focus still in Text1, press the ENTER key or the ESC key to activate
  Command1. The Validate event for Text1 does not occur and the Command1_Click
  event occurs, causing the form to close.

  To work around this problem so that you can validate the Text1 control when
  you activate the CommandButton via the ENTER or ESC keys, add validation code
  to the Command1_Click event. The following example shows one way in which you
  could validate the Text1 control:

        Private Sub Command1_Click()
           Dim ctl As Control

           ' Validation code for all controls that need validating:

           ' Set ctl to current control in which to validate:
           Set ctl = Screen.ActiveControl
           If TypeOf ctl Is TextBox Then
              If ctl.Name = "Text1" Then
                 ' Validation code for Text1:
                 If Trim(Text1.Text) = "" Then
                    ' Exit this procedure. Focus remains in Text1
                    Exit Sub
                 End If
              End If
           End If

           ' If Validation passes for all controls, the following
           ' code will execute:
           Unload Me
        End Sub

Additional query words: kbDSD kbDSupport kbVBp kbVBp600 kbCtrl

======================================================================
Keywords          : kbGrpDSVB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB600Search kbVBA600 kbVB600
Version           : WINDOWS:6.0
Issue type        : kbprb

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