Databinding Listbox Winforms

Question

This will have been answered in the other numerous threads on databinding and implementing INotifyPropertyChanged. However, I am still have difficulty getting this to work.

Essentially I have two listboxes, when the user selects the server name from the first listbox the second is supposed to provide a list of databases on that server. Pretty simple. The second listbox however is not displaying the updated list of databases.

Here is the code: Code to exec query and add data to the DatabaseList property.

        private void selection_Server_SelectionChangeCommitted(object sender, EventArgs e)
    {
        server = (string)selection_Server.SelectedItem;
        try
        {
            ExecDBList(server, ref vm);
        }

Class that manages properties used on the window.

    public class VM : INotifyPropertyChanged
{
    private static List<string> _dblist;
    public  List<string> DatabaseList
    {
        get
        {
            return _dblist;
        }
        set
        {
            if (_dblist != value)
            {
                _dblist = value;
            };
        }
    }
    public VM() { }

    void OnPropertyChanged(string PropertyName)
    {
            PropertyChanged(this, new PropertyChangedEventArgs(PropertyName));
    }

    public event PropertyChangedEventHandler PropertyChanged;

Code line on MainWindow initialization that assigns the listbox DataSource

            selection_RDM.DataSource = vm.DatabaseList;

Any help in getting this to work would be much appreciated as I'm struggling to understand the previous answers to databinding and using PropertyChangedEventHandler.

Thank you Richard

Still havn't got this working despite the below comments helping somewhat with my knowledge of the subject. — Richard Todd

Jordy van Eijk Jordy van Eijk · Accepted Answer · 2012-10-22T14:15:35

Try adding OnPropertyChanged(); after setting the value on _dblist like this:

public  List<string> DatabaseList
{
    get
    {
        return _dblist;
    }
    set
    {
        if (_dblist != value)
        {
            _dblist = value;
            OnPropertyChanged("DatabaseList");
        };
    }
}

There is no place where you call the notify so your application will not be notified about something that changed

Or better

change your OnPropertyChanged(string name) to private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")

and call this method without the name of the property on the same place as where i showed your like this

if (_dblist != value)
{
    _dblist = value;
    NotifyPropertyChanged();
};

Databinding Listbox Winforms

2 Answers