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#31845 Routing with optional parameters and fallback value - OnInitialized vs. OnParametersSet (#31859)

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Robert Haken 2024-02-20 13:03:38 +01:00 committed by GitHub
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aspnetcore/blazor/fundamentals/routing.md
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@ -304,14 +304,7 @@ Optional parameters aren't supported. In the following example, two [`@page` dir
:::moniker-end
Use [`OnParametersSet`](xref:blazor/components/lifecycle#after-parameters-are-set-onparameterssetasync) instead of [`OnInitialized{Async}`](xref:blazor/components/lifecycle#component-initialization-oninitializedasync) to permit app navigation to the same component with a different optional parameter value. Based on the preceding example, use `OnParametersSet` when the user should be able to navigate from `/route-parameter-2` to `/route-parameter-2/amazing` or from `/route-parameter-2/amazing` to `/route-parameter-2`:
```csharp
protected override void OnParametersSet()
{
Text = Text ?? "fantastic";
}
```
When the [`OnInitialized{Async}`](xref:blazor/components/lifecycle#component-initialization-oninitializedasync) method is used instead of [`OnParametersSet`](xref:blazor/components/lifecycle#after-parameters-are-set-onparameterssetasync), the default assignment of the `Text` property to `fantastic` doesn't occur if the user navigates within the same component. For example, this situation arises when the user navigates from `/route-parameter-2/amazing` to `/route-parameter-2`. As the component instance persists and accepts new parameters, the `OnInitialized` method isn't invoked again.
:::moniker range="< aspnetcore-6.0"