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guardrex merged 2 commits into from
Jul 28, 2022
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Preserve context for external events #26574

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Preserve context for external events
guardrex Jul 28, 2022
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guardrex Jul 28, 2022
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12 changes: 12 additions & 0 deletions aspnetcore/blazor/components/index.md
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Expand Up @@ -763,6 +763,9 @@ In the preceding example:
* `NotifierService` invokes the component's `OnNotify` method outside of Blazor's synchronization context. `InvokeAsync` is used to switch to the correct context and queue a render. For more information, see <xref:blazor/components/rendering>.
* The component implements <xref:System.IDisposable>. The `OnNotify` delegate is unsubscribed in the `Dispose` method, which is called by the framework when the component is disposed. For more information, see <xref:blazor/components/lifecycle#component-disposal-with-idisposable-and-iasyncdisposable>.

> [!IMPORTANT]
> If a Razor component defines an event that's triggered from a background thread, the component might be required to capture and restore the execution context (<xref:System.Threading.ExecutionContext>) at the time the handler is registered. For more information, see [Calling `InvokeAsync(StateHasChanged)` causes page to fallback to default culture (dotnet/aspnetcore #28521)](https://github.com/dotnet/aspnetcore/issues/28521).

## Use `@key` to control the preservation of elements and components

When rendering a list of elements or components and the elements or components subsequently change, Blazor must decide which of the previous elements or components can be retained and how model objects should map to them. Normally, this process is automatic and can be ignored, but there are cases where you may want to control the process.
Expand Down Expand Up @@ -2211,6 +2214,9 @@ In the preceding example:
* `NotifierService` invokes the component's `OnNotify` method outside of Blazor's synchronization context. `InvokeAsync` is used to switch to the correct context and queue a render. For more information, see <xref:blazor/components/rendering>.
* The component implements <xref:System.IDisposable>. The `OnNotify` delegate is unsubscribed in the `Dispose` method, which is called by the framework when the component is disposed. For more information, see <xref:blazor/components/lifecycle#component-disposal-with-idisposable-and-iasyncdisposable>.

> [!IMPORTANT]
> If a Razor component defines an event that's triggered from a background thread, the component might be required to capture and restore the execution context (<xref:System.Threading.ExecutionContext>) at the time the handler is registered. For more information, see [Calling `InvokeAsync(StateHasChanged)` causes page to fallback to default culture (dotnet/aspnetcore #28521)](https://github.com/dotnet/aspnetcore/issues/28521).

## Use `@key` to control the preservation of elements and components

When rendering a list of elements or components and the elements or components subsequently change, Blazor must decide which of the previous elements or components can be retained and how model objects should map to them. Normally, this process is automatic and can be ignored, but there are cases where you may want to control the process.
Expand Down Expand Up @@ -3211,6 +3217,9 @@ In the preceding example:
* `NotifierService` invokes the component's `OnNotify` method outside of Blazor's synchronization context. `InvokeAsync` is used to switch to the correct context and queue a render. For more information, see <xref:blazor/components/rendering>.
* The component implements <xref:System.IDisposable>. The `OnNotify` delegate is unsubscribed in the `Dispose` method, which is called by the framework when the component is disposed. For more information, see <xref:blazor/components/lifecycle#component-disposal-with-idisposable-and-iasyncdisposable>.

> [!IMPORTANT]
> If a Razor component defines an event that's triggered from a background thread, the component might be required to capture and restore the execution context (<xref:System.Threading.ExecutionContext>) at the time the handler is registered. For more information, see [Calling `InvokeAsync(StateHasChanged)` causes page to fallback to default culture (dotnet/aspnetcore #28521)](https://github.com/dotnet/aspnetcore/issues/28521).

## Use `@key` to control the preservation of elements and components

When rendering a list of elements or components and the elements or components subsequently change, Blazor must decide which of the previous elements or components can be retained and how model objects should map to them. Normally, this process is automatic and can be ignored, but there are cases where you may want to control the process.
Expand Down Expand Up @@ -4286,6 +4295,9 @@ In the preceding example:
* `NotifierService` invokes the component's `OnNotify` method outside of Blazor's synchronization context. `InvokeAsync` is used to switch to the correct context and queue a render. For more information, see <xref:blazor/components/rendering>.
* The component implements <xref:System.IDisposable>. The `OnNotify` delegate is unsubscribed in the `Dispose` method, which is called by the framework when the component is disposed. For more information, see <xref:blazor/components/lifecycle#component-disposal-with-idisposable-and-iasyncdisposable>.

> [!IMPORTANT]
> If a Razor component defines an event that's triggered from a background thread, the component might be required to capture and restore the execution context (<xref:System.Threading.ExecutionContext>) at the time the handler is registered. For more information, see [Calling `InvokeAsync(StateHasChanged)` causes page to fallback to default culture (dotnet/aspnetcore #28521)](https://github.com/dotnet/aspnetcore/issues/28521).

## Use `@key` to control the preservation of elements and components

When rendering a list of elements or components and the elements or components subsequently change, Blazor must decide which of the previous elements or components can be retained and how model objects should map to them. Normally, this process is automatic and can be ignored, but there are cases where you may want to control the process.
Expand Down
4 changes: 4 additions & 0 deletions aspnetcore/blazor/globalization-localization.md
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Expand Up @@ -898,6 +898,7 @@ To further understand how the Blazor framework processes localization, see the [
* [Resources in .resx Files](/dotnet/framework/resources/working-with-resx-files-programmatically)
* [Microsoft Multilingual App Toolkit](https://marketplace.visualstudio.com/items?itemName=MultilingualAppToolkit.MultilingualAppToolkit-18308)
* [Localization & Generics](http://hishambinateya.com/localization-and-generics)
* [Calling `InvokeAsync(StateHasChanged)` causes page to fallback to default culture (dotnet/aspnetcore #28521)](https://github.com/dotnet/aspnetcore/issues/28521)

:::moniker-end

Expand Down Expand Up @@ -1776,6 +1777,7 @@ To further understand how the Blazor framework processes localization, see the [
* [Resources in .resx Files](/dotnet/framework/resources/working-with-resx-files-programmatically)
* [Microsoft Multilingual App Toolkit](https://marketplace.visualstudio.com/items?itemName=MultilingualAppToolkit.MultilingualAppToolkit-18308)
* [Localization & Generics](http://hishambinateya.com/localization-and-generics)
* [Calling `InvokeAsync(StateHasChanged)` causes page to fallback to default culture (dotnet/aspnetcore #28521)](https://github.com/dotnet/aspnetcore/issues/28521)

:::moniker-end

Expand Down Expand Up @@ -2555,6 +2557,7 @@ Optionally, add a menu item to the navigation in `Shared/NavMenu.razor` for the
* [Resources in .resx Files](/dotnet/framework/resources/working-with-resx-files-programmatically)
* [Microsoft Multilingual App Toolkit](https://marketplace.visualstudio.com/items?itemName=MultilingualAppToolkit.MultilingualAppToolkit-18308)
* [Localization & Generics](http://hishambinateya.com/localization-and-generics)
* [Calling `InvokeAsync(StateHasChanged)` causes page to fallback to default culture (dotnet/aspnetcore #28521)](https://github.com/dotnet/aspnetcore/issues/28521)

:::moniker-end

Expand Down Expand Up @@ -3435,5 +3438,6 @@ To further understand how the Blazor framework processes localization, see the [
* [Resources in .resx Files](/dotnet/framework/resources/working-with-resx-files-programmatically)
* [Microsoft Multilingual App Toolkit](https://marketplace.visualstudio.com/items?itemName=MultilingualAppToolkit.MultilingualAppToolkit-18308)
* [Localization & Generics](http://hishambinateya.com/localization-and-generics)
* [Calling `InvokeAsync(StateHasChanged)` causes page to fallback to default culture (dotnet/aspnetcore #28521)](https://github.com/dotnet/aspnetcore/issues/28521)

:::moniker-end