ComboBox: Cancel SelectedIndexCh anged event

[almisba7]

Hi,
I have a ComboBox that contain ProductIDs and a DataGridView that lists Categories which a product can be a member of. My DataGridView list ALL categories, however, it has a checkbox column that get checked when the ProductID is a member of that Category, otherwise it is unchecked. A user may also check or uncheck a category checkbox then save.

The problem is, if a user forgot to save before changing the ComboBox, then his changes on the previous ProductID is gone!

How can I give the user a chance to either save or ignore the changes done on the previous ProductID (before selecting a new ProductID)?

I searched the internet for an answer and I found the following code but it is in C# and I am not sure if it solves the problem or not!!

Cheers

public class ComboBoxEx : ComboBox
{
   public event CancelEventHandler SelectedIndexChanging;
   [Browsable(false)]
   public int LastAcceptedSelectedIndex { get; private set; }
   public ComboBoxEx()
   {
      LastAcceptedSelectedIndex = -1;
   }
   protected void OnSelectedIndexChanging(CancelEventArgs e)
   {
      var selectedIndexChanging = SelectedIndexChanging;
      if (selectedIndexChanging != null)
         selectedIndexChanging(this, e);
   }
   protected override void OnSelectedIndexChanged(EventArgs e)
   {
      if (LastAcceptedSelectedIndex != SelectedIndex)
      {
         var cancelEventArgs = new CancelEventArgs();
         OnSelectedIndexChanging(cancelEventArgs);
         if (!cancelEventArgs.Cancel)
         {
            LastAcceptedSelectedIndex = SelectedIndex;
            base.OnSelectedIndexChanged(e);
         }
         else
            SelectedIndex = LastAcceptedSelectedIndex;
      }
   }
}
 

[tlhintoq]

I usually create a bool property called "IsDirty"
As soon as a change is made I make this bool "true", then call a method called "UpdateControls " which is a bunch of "enable" and "disable" actions based on the bool
When you save, mark the bool false and call "UpdateControls ()"

private void UpdateControls()
{
if (IsDirty)
{
     myComboBox.Enabled = false;// Now a change can't happen until I save
     btnSave.Enabled = true;
     this.Text = this.Text.TrimEnd('*') + "*"; // give the form title a * for dirty
}
else
{
     myComboBox.Enabled = true;
     btnSave.Enabled = false;// Why show a save button if its not dirty
     this.Text = this.Text.TrimEnd('*'); // Take away the * dirty mark
}
}
 

[almisba7]

Hi tlhintoq,

Well, it can be done your way, I was hoping though if I can have a custom changes to the "SelectedIndexC hanged" event of the combobox,,, just like the C# code I included. By the way I am a VB programmer not C#, actually I don't understand C#, the reason why I included that code is because I found that code in a site and they say it suppose to solve my problem, but I don't know how to translate it to VB! Did you check that code? What do you see?? Do you think it can do the trick?

Cheers

[tlhintoq]

Did you check that code? What do you see?? Do you think it can do the trick?

I did put that code into my "BytesTesti ng" little project that use to check things out from here. Yes it works. But will it work the way you think it does, for your purposes? I don't know. But what is it that you think it will do? It is a control inherited from ComboBox. It has a couple values such as "LastSelectedVa lue". You still need to write code to check if LastSelectedVal ue is what you saved etc.