Question

I do DataBinding in the following way

    private List<MyEditor> Editors { get; set; }
    private Dictionary<int,object> dictionary

    private void SetEditors()
    {
        Editors.Clear();

        foreach (var element in dictionary)
        {
            var editor = MyFactory.GetEditor();
            editor.DataBindings.DefaultDataSourceUpdateMode = DataSourceUpdateMode.OnPropertyChanged;
            editor.DataBindings.Add("Value", element, "Value");

            //some code

            Editors.Add(editor);

        }

        //some more code
    }

Then in GUI I do some changes to Value of Editors[0], after that in another piece of code I try to get value from dictionary element and find out that it hasn’t changed, even though I use Editors[0].DataBindings["Value"].WriteValue() to ensure data is written to dictionary.

In debugger I can see the following picture:

    Editors[0].DataBindings["Value"]    {System.Windows.Forms.Binding}  System.Windows.Forms.Binding
            ....
    DataSource  {[0, oldValue]} object {System.Collections.Generic.KeyValuePair<int,object>}
            ....

while

    Editors[0].Value    "newValue"  object {string}

What could it be? Will be grateful for any ideas.

Answer 1

I’m not certain I’m following correctly, but I believe the answer is that when you enumerate a Dictionary, the KeyValuePair (KVP) objects you get are created at the time of the enumeration. Enumerate it again and you will get a different set of objects. This is because a KVP is a value type.

To alter something referred to by a KVP, you have to return to the original Dictionary object. A data binding does not do that.