Binding in XAML allows interaction with data by displaying and updating data between UI elements and data sources. It can be difficult to understand as it involves concepts like DependencyProperties, INotifyPropertyChanged, and IValueConverter. Debugging bindings can provide cryptic error messages. Understanding that binding is just an object that describes the relationship between source and target properties and handles synchronization in the background is helpful context.

1. The Secret Sauce Behind
{Binding} in XAML
Brendon Page

2. {Overview}
• What is binding
• Why is it difficult
• Adding some Context
• Behind the scenes

3. {What Is It}
DataUI
textBox.Text = Value;
Value = textBox.Text;
<TextBox Text="{Binding}" />
• Mechanism for interacting with data.
• Display, convert, update data

4. {Quick Demo}

5. {Difficult}
• There’s a lot of other things you need to know
– DependencyObject /DependencyProperty
– INotifyPropertyChanged / INotifyCollectionChanged
– IValueConverter
• Cryptic debugging feedback
• It’s abstract
– MSDN (WPF) Overview
• More than 7500 words
• 12 Images
• 20 Code blocks

6. {A lot to know}

7. • All errors are shown in the output window
• When data source is set
– System.Windows.Data Error: 40 : BindingExpression path error: 'Name'
property not found on 'object' ''Person' (HashCode=46763000)'.
BindingExpression:Path=Name; DataItem='Person' (HashCode=46763000);
target element is 'TextBox' (Name=''); target property is 'Text' (type 'String')
• When data source isn’t set
–
{Debugging}

8. {Quick Demo}

9. {Context}
<Window>
<TextBox Text="{Binding Path=Name}" />
</Window >
public sealed partial class MainWindow : Window
{
public MainPage()
{
DataContext = new Person { Name = "Brendon" };
}
}
XAML
C# DataContext
Binding Uses
As it’s default datasource
Cascadesdown

10. {Just an Object}
<TextBox Text="{Binding Path=Name}" />
XAML
TextBox textBox = new TextBox();
C#
Binding binding = new Binding("Name");
textBox.SetBinding(TextBox.TextProperty, binding);
textBox.Text = binding;

11. Design Time
{But Wait There’s More}
Runtime
• Does the work
• Read & writes data between
source & target
• Subscribes to property changed events
• Maintains the relationship
• Describes the binding,
Source, Target, DataItem,
Path, Mode

12. {Conclusion}
• Interact with data
• Binding is tricky, until you understand it
• Context is important
• It’s just an object