Closing an inherited form in vb.net

[dazzy]

Hi All,

Firstly, I am new to inheritance, but understand the concept (probably at quite a simply level though).

 

I am having a problem with closing a form which I have inherited.

 

I have a form called frmAddForm_Simple, which contains 4 main controls (A Data Grid, A Save Button, A Close Button and a Text Box).

 

The idea around the form is to create a form which could be used for inputting of many different types of data which are all entered in the same way (i.e. to add a new row to a database for [status] table or [Location] table, all of which contain 2 columns in the database (an [id] and a [value]).

 

On the form I have a property called _FormChanged, which when the textbox text changes, sets the property to True.

 

I then have the following code on the Close Button:-

 

Public Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
       If _FormChanged Then
           If MessageBox.Show("Are you sure you want to close and discard any changes?", "Discard Changes", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = Windows.Forms.DialogResult.Yes Then
               Me.Close()
           End If
       End If
   End Sub

 

The form is opened as a dialog (ShowDialog) and when I go to close the inherited form (by click on btnClose) and answer No to the above MessageBox – the form closes anyway.

 

Using the Debugged I have worked out that the following events occur in sequence (all of which runs in the Master Form mentioned above):-

 

1) btnClose_Click sub Routine runs

2) I answer No to the question – do I want to close the form

3) The debugger steps over the Me.Close() line (as expected)

4) The debugger jumps up to the Sub Initialise (where ShowDialog was called from) and closes the form.

 

So at no point has the debugger even ran a line of code which reads Me.Close(), but the form closes anyway – so I’m fairly confused as to why the form should close.

 

If anyone could give me some pointers as to where I might be going wrong, I would much appreciate it. It’s obviously something I’m not understanding about inheritance – but whatever I read about on the subject, I seem go over the same things which (I think) I already understand, but I guess the light bulb hasn’t quite come on yet!

 

Many Thanks in advance for your time:) .

 

My Master Form (frmAddForm_Simple) Code:-

===================================================

Public Class frmAddForm_Simple
   Private _FormChanged As Boolean = False
   Private _FormLoading As Boolean = False

   Public Sub Initialise()
       _FormLoading = True
       StandardiseForm(Me)
       SetupForm()
       _FormLoading = False
       ShowDialog()
   End Sub

   Public Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
       If _FormChanged Then
           If MessageBox.Show("Are you sure you want to close and discard any changes?", "Discard Changes", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = Windows.Forms.DialogResult.Yes Then
               Me.Close()
           End If
       End If
   End Sub

   Public Overridable Sub SetupForm()

   End Sub

   Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
       SaveForm()
   End Sub

   Public Sub SaveForm()

   End Sub

   Private Sub SetFormStatus()
       _FormChanged = True
       If tData.Text.Trim <> "" Then btnSave.Enabled = True Else btnSave.Enabled = False
   End Sub

   Private Sub tData_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tData.TextChanged
       If Not _FormLoading Then
           SetFormStatus()
       End If
   End Sub
End Class

 

My Inherited (Child) Form Code:-

 

Public Class frmAdmin_PersonTitle
   Private Shadows _FormChanged As Boolean = False

   Public Overrides Sub SetupForm()
       lDataTitle.Text = "PersonTitle"
       Dim Data As New PersonTitle
       modGeneral.BindAndSetupGrid(grdData, Data.DataTable_Get(), Queries.PersonTitle.DefaultView())
   End Sub

   Public Shadows Sub SaveForm()
       Dim Data As New PersonTitle
       With Data.PersonTitleList
           .PersonTitleId.Value = 0
           .PersonTitle.Value = tData.Text.Trim
       End With

       If Not Data.UpdateCreate() Then
           MessageBox.Show("Failed to update/create new Person Title, please contact support", "Failed to Save", MessageBoxButtons.OK, MessageBoxIcon.Error)
       End If
       _FormChanged = False
       SetupForm()
   End Sub

End Class

Edited October 27, 2009 by dazzy

[PlausiblyDamp]

Does the button in question have a DialogResult assigned to it in the properties window?

[snarfblam]

If you add an event handler to the Closing event (or override the OnClosing method) you should be able to check the e.CloseReason. That may help explain why it is closing. You can also set a breakpoint here and look at he call stack (try enabling "Show External Code"). You may see the which function is calling Close() in there.

[dazzy]

Hi PlausiblyDamp/marble_eater

 

Thanks both for replying and the suggestions!!

 

I believe that I have resolved the issue - but I'm not sure as to why (what I have done) has resolved the issue.

 

I originally had the Cancel attribute of the master for set to btnClose. Whilst debugging this issue, I reset this property to none. Last night, I decided to delete and recreate the button and now everything works as I would expect!!

 

This morning, I set the Cancel property again to btnClose (just to make sure I was correct in my analysis) and the same thing happen (even when I reset the property - it still caused the form to close).

 

--------------------------------------------------------------------

 

PlausiblyDamp - No the DialogResult was originally set to Cancel (which I guess was a result of changing the Forms Cancel property) - but it's been set to None during my testing- good suggestion though!:)

----------------------------------------------------------------------

 

marble_eater - I have just tried that approach (I'd not thought of that one:)) and the Reason is "None" for both the Master forms closing event as well as the overridden one on the child form - Weird!!

 

Thanks!!

[BrettW]

Another way to get the msgbox result is:

 

Select Case(MsgBox("Are you sure you want to close and whatever...", MsgBoxStyle.Question + MsgBoxStyle.YesNo, "Are You Sure..."))

Case MsgBoxResult.Yes

me.close

case MsgBoxResult.No

End Select

 

OR:

 

Dim result As MsgBoxResult

result = (MsgBox("Are you sure you want to close and whatever...", MsgBoxStyle.Question + MsgBoxStyle.YesNo, "Are you sure?"))

If result = MsgBoxResult.Yes Then Me.Close()

 

:):):):):)