How to disable a combox item if it's already selected in another combobox in xaml c#?

Question

I have two combobox bind to the same ObservableCollection proprety, i would like to know if is possible to disable an item in combox if it's already selected in one of them ? in wpf. thx

Answer 1

You can either:

1. Set the IsEnabled property of the ComboBoxItem using something like this: Disallow/Block selection of disabled combobox item in wpf (Thanks Kamil for the link)
2. Make it look different (but still selectable);
3. Update the second list so it removes the selected option when the selection of the first changes; or
4. Apply validation after the fact (eg show an error icon/message, or disable the "submit" button if the two selections are the same).

Your choice will depend only on the experience you're trying to achieve.

Answer 2

You can bind the IsSelected property of the ComboBox item to a bool identifying a selected state in your class.

 <ComboBox ItemsSource="{Binding Items}">
        <ComboBox.ItemContainerStyle>
            <Style TargetType="ComboBoxItem">
                <Setter Property="IsSelected" Value="{Binding SelectedA, Mode=OneWayToSource}"></Setter>
                <Setter Property="IsEnabled" Value="{Binding SelectedB}"></Setter>
            </Style>
        </ComboBox.ItemContainerStyle>
    </ComboBox>
    <ComboBox ItemsSource="{Binding Items}">
        <ComboBox.ItemContainerStyle>
            <Style TargetType="ComboBoxItem">
                <Setter Property="IsSelected" Value="{Binding SelectedB, Mode=OneWayToSource}"></Setter>
                <Setter Property="IsEnabled" Value="{Binding SelectedA}"></Setter>
            </Style>
        </ComboBox.ItemContainerStyle>
    </ComboBox>

Create a class which exposes a couple of bools

        public class MyClass : INotifyPropertyChanged
    {
        private bool selectedA;

        public bool SelectedA
        {
            get { return !selectedA; }
            set { selectedA = value; if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("SelectedA")); }
        }

        private bool selectedB;

        public bool SelectedB
        {
            get { return !selectedB; }
            set { selectedB = value; if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("SelectedB")); }
        }

        public event PropertyChangedEventHandler PropertyChanged;
    }

(In the example I am simply reversing each selected bool in the getter, but in reality flipping the bool would probably be best performed using a converter)