Question

Is it possible to cancel adding an item inside BindingSource.AddingNew event handler?

When user clicks on the “Add new” button in my BindingNavigator, I am opening a dialog which may or may not return a valid file. Right now, I have something like this:

void bindingSource_AddingNew(object sender, AddingNewEventArgs e)
{
    using (var dialog = new OpenFileDialog())
    {
        var result = dialog.ShowDialog();

        // user canceled?
        if (result == DialogResult.Cancel)
            return;

        // TryLoad will return null on failure
        var data = TryLoad(dialog.FileName);

        // only add the item to the grid if not null
        if (data != null)
            e.NewObject = data;
    }
}

Even if I don’t set e.NewObject to a value inside the handler, a new (“empty”) item appears in the DataGridView.

Is it possible to cancel adding the item?

Answer 1

A simple solution:

1. Clear the BindingNavigator “AddNewItem” property in Properties window, so that it doesn’t fire bindingsource AddingNew.

2. Double click on the plus sign in bindingNavigator to generate Click event for the plus button and manually control add new item procedure, like the following:

   private void bindingNavigatorAddNewItem_Click(object sender, EventArgs e)
   {
       using (var dialog = new OpenFileDialog())
       {
           if (dialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
           {
               var data = TryLoad(dialog.FileName); ;
   
               if (data != null)
               {
                   myBindingSource.Add(data);
               }
           }
       }
   }