CODEWITHSUNDEEP
vb.netwinformsvb6-migration
BlueRaja - Danny Pflughoeft
BlueRaja - Danny Pflughoeft

Reputation: 85996

Forms retaining values after closing

Throughout our program, forms are opened like this:

FormName.SomeValue = 10
FormName.ShowDialog()

rather than the usual

Dim myForm As New FormName
myForm.SomeValue = 10
myForm.ShowDialog()

(There is nothing we could do about this - this was done automatically by the Visual Studio VB6 --> VB.Net converter)

The problem is that when forms are closed, they seem to not really be closed, only hidden - if I add some text to a textbox and close/reopen the form, the text is still there, rather than the textbox being cleared like normal. This is presumably because the form always uses the same instance.

Is there any easy way to fix this other than going through the entire program and creating a new form instance for every ShowDialog() call (there are hundreds)?

We considered resetting every control in every form's Load event, but that would still be a pain, so we figured we'd ask if there's a simpler way first.

Upvotes: 3

Views: 8379

Answers (6)

vvn01
vvn01

Reputation: 11

I know this is super late but-

Form1.Dispose()

works for me. It resets the textboxes.

Upvotes: 1

miroxlav
miroxlav

Reputation: 12194

You asked for easy way to fix this:

Change your ShowDialog() procedure/function calls in the following way:


   AS PROCEDURE                       |   AS FUNCTION
                                      | 
    FormName.ShowDialog()             |    r = FormName.ShowDialog()
    FormName.ShowDialog()             |    r = FormName.ShowDialog()
                                      |
   CHANGE TO                          |   CHANGE TO
                                      |
    Call New FormName.ShowDialog()    |    r = New FormName.ShowDialog()
    Call New FormName.ShowDialog()    |    r = New FormName.ShowDialog()

Upvotes: 1

Steve Massing
Steve Massing

Reputation: 1893

What you are dealing with is called the form's "default instance" and is a carry over from the VB6 days. It is not recommended practice to use it. You may not want to hear it, but the best long-term strategy for your code base is to rewrite the form initializers the correct way than to do some hacky workaround in the form Load() events. You may hate it now, but you will appreciate it the next time you have to work on this code. You can probably even put together a snippet to do most of the typing for you.

Upvotes: 2

hungryMind
hungryMind

Reputation: 6999

public class MyForm: Form{

   private static MyForm myForm = null;

   public static DialogResult ShowDialog(bool newForm){
          if(newForm)
          {
                if(myForm != null) 
                    myForm.Dispose();
                myForm= new MyForm();
          }
          return myForm.ShowDialog();
   }

   public static DialogResult ShowDialog(){
          return ShowDialog(true);
   }
}

Upvotes: 4

pstrjds
pstrjds

Reputation: 17428

Edit: How to display the form using the Using statement

Using formName AS New FormName
    formName.SomeValue = 10
    formName.ShowDialog()
End Using

It appears from the code displayed here that there is now a static ShowDialog call that was added to your FormName class. You should be able to edit just this method to dispose of the old form and create and display the new one. This would help you avoid changing code all over the place, just in the one location.

Upvotes: 1

indiPy
indiPy

Reputation: 8062

  1. If the question is about clearing text boxes then I would have Cleared all of them RECURSIVELY

      For Each Control in Controls
      If Control is type of TextBox
      Control.Clear
  Next

  2. If you are binding controls by any DATASOURCE I would suggest to clear the Datasource and REBIND

  3. Override the ShowDialog() Method.

Upvotes: 0

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