WPF Binding result not being retained

Question

Hi Could someone tell me what i am missing here..i am adding all the code required below...When i check the check boxes the binding does fire and set the Source value..but when i click the button and check the value the value is not true eventhough the check box is checked..
Thanks in advance..

namespace Window1
{
    public struct Opt
    {
        private string _OptionsName;
        private bool _IsSelected;

        public Opt(string Opt, bool IsSelected)
            : this()
        {
            _OptionsName = Opt; _IsSelected = IsSelected;
        }
        public string OptionsName
        {
            get { return this._OptionsName; }
            set
            {
                this._OptionsName = value;
            }
        }
        public bool IsSelected
        {
            get { return this._IsSelected; }
            set
            {
                this._IsSelected = value;               
            }
        }
    }

    public class Options : INotifyPropertyChanged
    {
        #region Private members
        private string _Field;
        private List<Opt> _Filters;       
        #endregion

        #region Public Properties
        public string Field
        {
            get { return _Field; }
            set
            {
                _Field = value;
                NotifyPropertyChanged("Field");
            }
        }

        public List<Opt> Filters
        {
            get { return _Filters; }
            set
            {
                _Filters = value;
                NotifyPropertyChanged("Filters");
            }
        }
       
        #endregion

        #region Constructor
        public Options()
        {
            this._Filters = new List<Opt>();
        }
        #endregion

        #region Public Methods
        public void Load(List<string> Options)
        {
            if (Options != null && Options.Count > 0)
            {
                foreach (string sFilter in Options)
                {
                    Opt Opt = new Opt(sFilter, false);                   
                    this._Filters.Add(Opt);
                }
            }
        }
       
        #endregion

        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(String FieldName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(FieldName));
            }
        }

        #endregion

    }
}

///////////////////////////////////////////
<Grid>
        <StackPanel Orientation="Horizontal">
        <Label Content="Field" Height="50" Width="200"></Label>
        <ComboBox Name="cmb" ItemsSource="{Binding Filters}" Height="30">
            <ComboBox.ItemTemplate>
                <DataTemplate>
                    <CheckBox Content="{Binding OptionsName}" IsChecked="{Binding IsSelected}"></CheckBox>
                </DataTemplate>
            </ComboBox.ItemTemplate>
        </ComboBox>
            <Button Name="btn" Click="btn_Click" Height="40">jjjj</Button>
            </StackPanel>
    </Grid>

/////////////////////////////////////////
public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }
        Options filters = new Options();
        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            List<string> values = new List<string>();
            values.Add("AAA");
            values.Add("BBB");
            values.Add("BBB");

           
            filters.Field = "Heading";
            filters.Load(values);
            this.cmb.DataContext = filters;
        }

        private void btn_Click(object sender, RoutedEventArgs e)
        {
            string s = filters.Field;
        }
    }

Answer 1

Hi,

this is a nice one. The problem is that, because structs are value types, what the combobox changes is actually copies of your listed Opts, not the Opts themselves. Change the declaration to class and it works...

By the way, the change notification for Options.Filters doesn't work, because it only fires when a new instance of the list is assigned, and the items in the list themselves don't provide change notification. However, you might not need that anyway...

Answer 2

Awesome! Thanks a lot hbarck!