.NET Databinding ignores property change

I have written a control in C# that derives from System.Windows.Forms.Control. I have added a property Selected to which I want to databind to a business entity using a BindingSource.

I’ve implemented the PropertyNameChanged pattern by adding a SelectedChanged event that I fire when the Selected property is changed.

This is my code:

public partial class RateControl : Control
{
    [Category("Property Changed")]
    public event EventHandler SelectedChanged;

    public int Selected
    {
      get
      { return m_selected; }
      set
      {
        if (m_selected != value)
        {
          m_selected = value;
          OnSelectedChanged();
          Invalidate();
        }
      }
    }

    protected virtual void OnSelectedChanged()
    {
      if (this.SelectedChanged != null)
        this.SelectedChanged(this, new EventArgs());
    }
}

When I bind to the Selected property, I see the event being subscibed to. The event is also fired when the property changes.

However the business entity is not updated. I don’t even see the getter of the Selected property being accessed.

What am I missing?

From stackoverflow

• Have you got the binding's update mode set to DataSourceUpdateMode.OnPropertyChanged? Either via binding.DataSourceUpdateMode = DataSourceUpdateMode.OnPropertyChanged;, or using one of the DataBindings.Add(...) overloads.

  The following works for me to push values to the business object...

  using System;
  using System.Diagnostics;
  using System.Windows.Forms;
  
  class MyForm : Form
  {
      public MyForm()
      {
          MyBusinessObject obj = new MyBusinessObject();
          Button btn = new Button();
          btn.Click += delegate { Foo++; };
          DataBindings.Add("Foo", obj, "Bar", false, DataSourceUpdateMode.OnPropertyChanged);
          DataBindings.Add("Text", obj, "Bar");
          Controls.Add(btn);
      }
  
      private int foo;
      public event EventHandler FooChanged;
      public int Foo
      {
          get { return foo; }
          set
          {
              if (foo != value)
              {
                  foo = value;
                  Debug.WriteLine("Foo changed to " + foo);
                  if (FooChanged != null) FooChanged(this, EventArgs.Empty);
              }
          }
      }
  }
  
  class MyBusinessObject
  {
      private int bar;
      public event EventHandler BarChanged;
      public int Bar
      {
          get { return bar; }
          set
          {
              if (bar != value)
              {
                  bar = value;
                  Debug.WriteLine("Bar changed to " + bar);
                  if (BarChanged != null) BarChanged(this, EventArgs.Empty);
              }
          }
      }
  }
  
  static class Program
  {
      [STAThread]
      static void Main()
      {
          Application.Run(new MyForm());
      }
  }