Where / When / How does BindingList<T> convert / wireup PropertyChanged to ListChanged event

Question

Hello all,

I have a hierarchy of objects that all implement INotifyPropertyChanged. I also have a custom list that derives from BindingList.

It is my understanding that when I add an object that impelements INotifyPropertyChanged to the list, that somehow the PropertyChanged event is automagically wired-up / converted to the ListChanged event.

However, after I set my list as the datasource of my DataGridView, when I change a value in the grid, the ListChanged event does not fire... When I step into the code, it turns out that the PropertyChanged() event is not triggering becaue it is null, which I assume to mean that it is not getting wired-up / converted to the BindingList's ListChanged event, like its supposed to...

For example:

public class Foo : INotifyPropertyChanged
{
     //Properties...
     private string _bar = string.Empty;
     public string Bar
     {
         get { return this._bar; }
         set
         {
              if (this._bar != value)
              {
                  this._bar = value;
                  this.NotifyPropertyChanged("Bar");
              }
         }
     }

     //Constructor(s)...
     public Foo(object seed)
     {
         this._bar = (string)object;
     }

     //PropertyChanged event handling...
     public event PropertyChangedEventHandler PropertyChanged;
     protected void NotifyPropertyChanged(String info)
     {
         if (this.PropertyChanged != null)
         {
             this.PropertyChanged(this, new PropertyChangedEventArgs(info));
         }
     }
}

And here is my custom list class...

public class FooBarList : BindingList<Foo>
{
     public FooBarList(object[] seed)
     {
          for (int i = 0; i < seed.Length; i++)
          {
             this.Items.Add(new Foo(this._seed[i]));
          }
     }
}

Any ideas or suggestions?

Thanks!

Josh

Answer 1

I think the problem is that you're calling this.Items.Add() instead of this.Add(). The Items property returns the base List<T>, whose Add() method doesn't have the functionality you want.