Bind Textbox to Func<T> (Linq query)

Question

I am working on a side project where I have hit a wall after much poking around and could use some help.

Here is the situation: I have a Window that I want to dynamically populate based on a choice in a combobox (easy) so I am building everything programmatically. What I need to build is several boxes that will populate based off of different queries in the same result set. What I was planning on doing was setting the Binding.Source (of the textbox text property) to a Func and that when update source was called then it would auto-magically run that function.

That doesn't happen. Any thoughts on how to bind a text property to a LINQ query that will change over time?

I can provide any more info that is required.

Thanks, Nick

Update Snippets:

    private int AllelePopulation(IAllele allele)
    {
        var list= from b in _population.Populus
            from g in b.Genes
            where g.Representation == allele.Representation
            select b;
        return list.ToList().Count;
    }

Setting the func as the binding source (parameter name is bindingSource)

    var binding = new Binding
    {
        Source = bindingSource,
        Mode = BindingMode.OneWay
    };
    tb.SetBinding(TextBox.TextProperty, binding);

Answer 1

Something has to do the "magic". In your case it would be a converter which converts a lambda expression to a string.

class Conv : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return ((Func<string>)value)();
    }

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

/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        var binding = new Binding
        {
            Source = (Func<string>)AllelePopulation,
            Mode = BindingMode.OneWay,
            Converter = new Conv()
        };
        textBox.SetBinding(TextBox.TextProperty, binding);
    }

    private string AllelePopulation()
    {
        return "test";
    }
}

Answer 2

Do you implement INotifyPropertyChanged?

How about this simple approach for your viewmodel/data context:

public class DC : INotifyPropertyChanged
{

    // access to you Func<string> is simply via a property
    // this can be used by setting the binding in code or in XAML
    public string Allele
    {
        get { return MyFunc(); }
    }


    // whenever a variable used in your function changes, raise the property changed event
    private int I
    {
        get { return i; }
        set { i = value; OnPropertyChanged("Allele"); }
    }
    private int i;

    public void Modify()
    {
        // by using the property, the change notification is done implicitely
        I = I + 1;
    }

    // this is your private int AllelePopulation(IAllele allele) function

    private string MyFunc()
    {
        return (I*2).ToString();
    }




    // property changed notification
    public event PropertyChangedEventHandler PropertyChanged;
    [NotifyPropertyChangedInvocator]
    private void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        var handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }
}