Question

I’m new to WPF and trying to figure out all this databinding stuff. When I do the following in my code, my ComboBox is populated when I run my application:

public NewForm()
{
    InitializeComponent();
    Product.ItemsSource = Products;
}

public List<string> Products
{
    get { return _productsComponents.Keys.ToList(); }
}

However, in my XAML when I have the following, the ComboBox has no content in it when I run my application:

<ComboBox Height="23" HorizontalAlignment="Left" Margin="138,116,0,0"
          Name="Product" VerticalAlignment="Top" Width="120"
          ItemsSource="{Binding Path=Products}"/>

Am I referencing something incorrectly? This tutorial was helpful but he never set ItemsSource in XAML, always in C#.

Answer 1

By default, you’re actually binding not to the form itself, but to the object assigned to the DataContext property. This facilitates using a view model to manage all the data outside the codebehind files.

You can probably assign the form itself to the DataContext property in the constructor

DataContext = this;

You can also bind to the form in any of several ways. Here is one:

<Window x:Name="thisWindow" …
    <ComboBox ItemsSource="{Binding Path=Products, ElementName=thisWindow}"…

I don’t think that Products needs to be a DependencyProperty here, but don’t quote me on that, and as long as the collection is not subject to change, you don’t need to worry about update notifications.