PRB: No Validate Event When Activating CommandButton

• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, version 6.0

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 : kbGrpVB
Version : WINDOWS:6.0
Platform : WINDOWS
Issue type : kbprb