Property setter not getting called with CollectionEditor

Question

I have a custom control that has an Items property. I Have applied an EditorAttribute with a UITypeEditor of type CollectionEditor.

Collection Type:

[Serializable]
[Editor(typeof(CollectionEditor), typeof(UITypeEditor))]
public class ListItemsCollection : CollectionBase
{
    // methods
}

Property Declaration In The Control:

private new ListItemsCollection _Items;

[Editor(typeof(CollectionEditor), typeof(UITypeEditor))]
public new ListItemsCollection Items
{
    get
    {
        return _Items;
    }
    set
    {
        _Items = value;

        // do other UI changes
    }
}

Problem:
When I drop this control to the designer surface, I am able to add items to the Items property using the PropertyGrid. But, the when I click the Ok button of the CollectionEditor the setter of the Items property is not getting called.

AFAIK when a value is returned from the EditValue method of a UITypeEditor class the setter block of the property is supposed to be called.

This is driving me insane. I even tried adding Event's to the ListItemsCollection, so that when Items are added, I can whatever I want with the control's ui.

This is not supposed to be hard. What am I doing wrong?

Answer 1

Collection properties should be read-only. It's the collection that is retrieved through the getter, and adjusted. The setter never enters into it, because that would mean setting a new collection.

Answer 2

I try to reprodeuce your situation: using following code, I get a message box showing whenever I edit the list from VS property window. Beware that you have to create the list by yourself. If you don't create it, VS create a temp list which you can edit from property window, but does not set your property to this list (so your setter will never be called)

    public UserControl1()
    {
        InitializeComponent();
        list = new BindingList<ListViewItem>();
        list.ListChanged += new ListChangedEventHandler(list_ListChanged);
    }

    void list_ListChanged(object sender, ListChangedEventArgs e)
    {
        MessageBox.Show(e.ListChangedType.ToString());
    }

    private BindingList<ListViewItem> list;

    public BindingList<ListViewItem> List1
    {
        get { return list; }
    }