Paul Stovell says…

Update: SyncLINQ has been released under the name Bindable LINQ, and is available from CodePlex

My last couple of posts have hinted at it, but now it’s finally here: SyncLINQ running within Silverlight 2.0 beta 1. If you have it installed, you should see the application below:

Go ahead, try it out:

• Type in the filter
• Add an item that passes your filter - it should appear, and should be in the correct order
• Add an item that doesn’t pass your filter - it won’t appear

Now you’re wondering: how much code did it take to write that?

Here’s the class representing a Contact - a plain old .NET class:

public class Contact : INotifyPropertyChanged
{
    private string _name;
    private string _company;
    private string _phoneNumber;

    public Contact()
    {

    }

    public string Name
    {
        get { return _name ?? ""; }
        set
        {
            _name = value;
            this.OnPropertyChanged(new PropertyChangedEventArgs("Name"));
        }
    }

    public string PhoneNumber
    {
        get { return _phoneNumber ?? ""; }
        set
        {
            _phoneNumber = value;
            this.OnPropertyChanged(new PropertyChangedEventArgs("PhoneNumber"));
        }
    }

    public string Company
    {
        get { return _company ?? ""; }
        set
        {
            _company = value;
            this.OnPropertyChanged(new PropertyChangedEventArgs("Company"));
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(PropertyChangedEventArgs e)
    {
        PropertyChangedEventHandler handler = this.PropertyChanged;
        if (handler != null)
        {
            handler(this, e);
        }
    }
}

And here’s the code-behind for the Silverlight Page:

public partial class Page : UserControl
{
    private ObservableCollection<Contact> _contacts;

    public Page()
    {
        InitializeComponent();
        _contacts = new ObservableCollection<Contact>();
        _contacts.Add(new Contact() {Name = "Paul Stovell", Company = "Readify", PhoneNumber = "0421 938 793"});
        _contacts.Add(new Contact() {Name = "Omar Besiso", Company = "Readify", PhoneNumber = "0421 938 793"});
        _contacts.Add(new Contact() {Name = "Darren Neimke", Company = "Readify", PhoneNumber = "0421 938 793"});
        _contacts.Add(new Contact() {Name = "Mitch Denny", Company = "Readify", PhoneNumber = "0421 938 793"});
        _contacts.Add(new Contact() {Name = "Richard Banks", Company = "Readify", PhoneNumber = "0421 938 793"});
        _contacts.Add(new Contact() {Name = "Andrew Matthews", Company = "Readify", PhoneNumber = "0421 938 793"});

        _contactsList.ItemsSource = _contacts.AsBindable()
                                    .Where(c => c.Name.ToLower().StartsWith(this.FilterTextBox.Text.ToLower()))
                                    .OrderBy(c => c.Name.ToLower());

        _newItemPanel.DataContext = new Contact();
    }

    public TextBox FilterTextBox
    {
        get { return _filterTextBox; }
    }

    private void SaveButton_Click(object sender, RoutedEventArgs e)
    {
        Contact contact = (Contact)_newItemPanel.DataContext;
        _contacts.Add(contact);
        _newItemPanel.DataContext = new Contact();
    }
}

The public property exposing the FilterTextBox is a workaround because you can’t invoke private members via reflection in Silverlight. I would have used x:FieldModifier on the element, but that doesn’t seem supported by Silverlight yet (the .g.cs generator respects it, but Silverlight borks at runtime when it encountered the attribute).

Apart from some temporary compatibilities and missing features, overall I’m really happy about the Silverlight developer story. I will post some more thoughts on this later. For now, goodbye JavaScript!

Note: the background image in the Silverlight application is a photo by Bill McCarthy. Bill has lots of nice photos, and I hope he doesn’t mind me using this one in a sample

Filed under: Bindable LINQ