WPF MVVM Radio buttons on ItemsControl

Question

I\'ve bound enums to radio buttons before, and I generally understand how it works. I used the alternate implementation from this question: How to bind RadioButtons to an e

Answer 1

You are so close. When you are need two bindings for one converter you need a MultiBinding and a IMultiValueConverter! The syntax is a little more verbose but no more difficult.

• MultiBinding Class
• IMultiValueConverter Interface

Edit:

Here's a little code to get you started.

The binding:

and the converter:

public class EqualsConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        return values[0].Equals(values[1]);
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

Second Edit:

The above approach is not useful to implement two-way binding using the technique linked in the question because the necessary information is not available when converting back.

The correct solution I believe is straight-up MVVM: code the view-model to match the needs of the view. The amount of code is quite small and obviates the need for any converters or funny bindings or tricks.

Here is the XAML;

and code-behind to simulate the view-model:

        DataContext = new CheckBoxValueCollection(new[] { "Foo", "Bar", "Baz" });

and some view-model infrastructure:

    public class CheckBoxValue : INotifyPropertyChanged
    {
        private string description;
        private bool isChecked;

        public string Description
        {
            get { return description; }
            set { description = value; OnPropertyChanged("Description"); }
        }
        public bool IsChecked
        {
            get { return isChecked; }
            set { isChecked = value; OnPropertyChanged("IsChecked"); }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        protected void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    public class CheckBoxValueCollection : ObservableCollection
    {
        public CheckBoxValueCollection(IEnumerable values)
        {
            foreach (var value in values)
                this.Add(new CheckBoxValue { Description = value });
            this[0].IsChecked = true;
        }

        public string SelectedItem
        {
            get { return this.First(item => item.IsChecked).Description; }
        }
    }