Skip to content

Add missing BindableAttribute information for C++/WinRT data binding in Windows App SDK documentation #5600

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Aug 26, 2025
Merged

Add missing BindableAttribute information for C++/WinRT data binding in Windows App SDK documentation #5600

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
804579b
Initial plan
Copilot Aug 26, 2025
1b29c44
Add missing BindableAttribute information for C++/WinRT data binding
Copilot Aug 26, 2025
9e28f05
Apply suggestions from code review
alvinashcraft Aug 26, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
21 changes: 21 additions & 0 deletions hub/apps/develop/data-binding/data-binding-in-depth.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -162,6 +162,11 @@ In the two examples below, the `Button.Content` property is the binding target,
<Button Content="{Binding ...}" ... />
```

If you're using C++/WinRT, then you'll need to add the [**BindableAttribute**](/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.data.bindableattribute) attribute to any runtime class that you want to use the [{Binding}](/windows/uwp/xaml-platform/binding-markup-extension) markup extension with.

> [!IMPORTANT]
> If you're using C++/WinRT, then the [**BindableAttribute**](/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.data.bindableattribute) attribute is available with Windows App SDK. Without that attribute, you'll need to implement the [ICustomPropertyProvider](/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.data.icustompropertyprovider) and [ICustomProperty](/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.data.icustomproperty) interfaces in order to be able to use the [{Binding}](/windows/uwp/xaml-platform/binding-markup-extension) markup extension.

### Binding object declared using {x:Bind}

There's one step we need to do before we author our [{x:Bind}](/windows/uwp/xaml-platform/x-bind-markup-extension) markup. We need to expose our binding source class from the class that represents our page of markup. We do that by adding a property (of type `HostViewModel` in this case) to our `MainWindow` window class.
Expand Down Expand Up @@ -234,6 +239,22 @@ Code to support `{x:Bind}` is generated at compile-time in the partial classes f

### Binding object declared using {Binding}

If you're using C++/WinRT then, to use the [{Binding}](/windows/uwp/xaml-platform/binding-markup-extension) markup extension, you'll need to add the [**BindableAttribute**](/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.data.bindableattribute) attribute to any runtime class that you want to bind to. To use [{x:Bind}](/windows/uwp/xaml-platform/x-bind-markup-extension), you don't need that attribute.

```cppwinrt
// HostViewModel.idl
// Add this attribute:
[Microsoft.UI.Xaml.Data.Bindable]
runtimeclass HostViewModel : Microsoft.UI.Xaml.Data.INotifyPropertyChanged
{
HostViewModel();
String NextButtonText;
}
```

> [!IMPORTANT]
> If you're using C++/WinRT, then the [**BindableAttribute**](/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.data.bindableattribute) attribute is available with Windows App SDK. Without that attribute, you'll need to implement the [ICustomPropertyProvider](/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.data.icustompropertyprovider) and [ICustomProperty](/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.data.icustomproperty) interfaces in order to be able to use the [{Binding}](/windows/uwp/xaml-platform/binding-markup-extension) markup extension.

[{Binding}](/windows/uwp/xaml-platform/binding-markup-extension) assumes, by default, that you're binding to the [**DataContext**](/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.frameworkelement.datacontext) of your markup window. So we'll set the `DataContext` of our window to be an instance of our binding source class (of type `HostViewModel` in this case). The example below shows the markup that declares the binding object. We use the same `Button.Content` binding target we used in the "Binding target" section earlier, and we bind to the `HostViewModel.NextButtonText` property.

``` xaml
Expand Down