ListView Item - Generate column value based on criteria not part of Item's class

Question

Suppose I've a simple model class:

public class Car
{
    public string Make { get; init; }
    public string Model { get; init; }
    public string Year { get; init; }
}

In my ViewModel, I've two lists:

public class ViewModel
{
    public ObservableCollection<Car> Cars { get; }
    public List<Car> CanBeSold { get; }

    public ViewModel()
    {
        Car car1 = new() { Make = "Toyota", Model = "Corolla", Year = "2020" };
        Car car2 = new() { Make = "Honda", Model = "Civic", Year = "2021" };
        Car car3 = new() { Make = "Mitsubishi", Model = "Lancer", Year = "2017" };

        Cars = new();
        CanBeSold = new();

        Cars.Add(car1);
        Cars.Add(car2);
        Cars.Add(car3);

        CanBeSold.Add(car2);
    }
}

In my view, I'm bidining a ListView to the Cars collection:

<ListView ItemsSource="{Binding Cars}">
    <ListView.View>
        <GridView>
            <GridViewColumn Header="Make" DisplayMemberBinding="{Binding Path=Make}"/>
            <GridViewColumn Header="Model" DisplayMemberBinding="{Binding Path=Model}"/>
            <GridViewColumn Header="Year" DisplayMemberBinding="{Binding Path=Year}"/>
            <GridViewColumn Header="Can Be Sold"/>
        </GridView>
    </ListView.View>
</ListView>

How can I also show a Yes/No based on if the Car is in the list CanBeSold?

Thanks for any help.

Answer 1

You may use a MultiBinding that contains a Binding to the CanBeSold property of the parent view model and a Binding to the current Car element.

<GridViewColumn Header="Can Be Sold">
    <GridViewColumn.DisplayMemberBinding>
        <MultiBinding>
            <MultiBinding.Converter>
                <local:ListElementConverter/>
            </MultiBinding.Converter>
            <Binding Path="DataContext.CanBeSold"
                     RelativeSource="{RelativeSource AncestorType=ListView}"/>
            <Binding />
        </MultiBinding>
    </GridViewColumn.DisplayMemberBinding>
</GridViewColumn>

The Binding Converter checks if the element is contained in the list:

public class ListElementConverter : IMultiValueConverter
{
    public object Convert(
        object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        return values.Length == 2 &&
            values[0] is IList list &&
            list.Contains(values[1])
            ? "Yes"
            : "No";
    }

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