[Pre4] Final round of Blazor content/WN updates

[guardrex]

Addresses #34437
Addresses #35217
Fixes #35233
Fixes #35231
Fixes #35439

This PR will be held until P4 releases.

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Internal previews

📄 File	🔗 Preview link
aspnetcore/blazor/components/quickgrid.md	aspnetcore/blazor/components/quickgrid
aspnetcore/blazor/fundamentals/routing.md	aspnetcore/blazor/fundamentals/routing
aspnetcore/blazor/fundamentals/static-files.md	aspnetcore/blazor/fundamentals/static-files
aspnetcore/blazor/performance/webassembly-browser-developer-tools-diagnostics.md	aspnetcore/blazor/performance/webassembly-browser-developer-tools-diagnostics

[guardrex]

@ilonatommy ... The Not Found content is on this wrap-up PR. One question comes to mind ...

For the OnNotFound scenario, can we do anything inside of OnNotFound here with the sender or args? I tried casting args to NotFoundEventArgs, but there doesn't seem to be anything interesting that can be done with it.

[guardrex]

@ilonatommy ... We've hit release, so I'm going to go ahead with this. You can let me know here if you have update requests. Also, there's that one question that I asked in the last comment.

[ilonatommy]

For the OnNotFound scenario, can we do anything inside of OnNotFound here with the sender or args?

No, they are left there for possible future use, currently they do not play any role.

Sorry for the delay, I will review now and post comments.

Edit: I read it and I have no comments, everything looks awesome. Out of curiosity, why do we copy-paste the same content to aspnetcore/release-notes/aspnetcore-10/includes/blazor.md and aspnetcore/blazor/fundamentals/routing.md? Cross-linking these sections would not look good?

[guardrex]

It depends on the coverage. If the new feature coverage is somewhat short, I'll often place a copy into both places and not bother with a cross-link. If the coverage is long and/or has long examples, I tend to place a general description into the What's New article and cross-link to the reference article content. If you ever feel that the What's New article should have more or less coverage for a feature, let me know 👂. I can move coverage one way or the other. If the coverage is different, I always place a cross-link.

WRT OnNotFound, Dan told me last night in a message that it might be more useful for developers working on custom routers. We could say more about why it's there, and we could improve the example to make it actually do something valuable ... an actual use case that makes sense. I'm 👂 on if we can improve that bit of the coverage.

[guardrex]

... and Dan said something that we should probably place for OnNotFound ...

We should just be clear that the event is only fired when NavigationManager.NotFound is called, and not for any 404 response.

I'll keep that in mind for a patch PR today after I hear back from you.

[ilonatommy]

WRT OnNotFound, Dan told me last night in a message that it might be more useful for developers working on custom routers. We could say more about why it's there, and we could improve the example to make it actually do something valuable ... an actual use case that makes sense. I'm 👂 on if we can improve that bit of the coverage.

I believe the use cases for custom router would be (I have not tested any of these):

• A/B testing:

public class ExperimentRouter : ComponentBase
{
    [Inject] private NavigationManager NavigationManager { get; set; }
    [Inject] private IExperimentService ExperimentService { get; set; }
    
    protected override void OnInitialized()
    {
        var uri = NavigationManager.Uri;        
        if (uri.Contains("/new-feature") && !ExperimentService.IsInExperimentGroup("new-feature-test"))
        {
            // Users not in test group get 404 - feature doesn't exist for them
            NavigationManager.NotFound();
        }
    }
}

• dynamic route validation e.g.

if (!IsValidRoute(requestedPath))
{
    NavigationManager.NotFound();
    return;
}

• Internationalized routing, when url with requested locale doesn't exist:

if (!supportedLocales.Contains(requestedLocale))
{
    NavigationManager.NotFound();
}

[guardrex]

I see, but those use cases are going to result in Not Found being triggered. I'm not clear on what custom code would be placed into the OnNotFound event for those or other scenarios that would do something useful.

[ilonatommy]

I see, but those use cases are going to result in Not Found being triggered. I'm not clear on what custom code would be placed into the OnNotFound event for those or other scenarios that would do something useful.

Right. Then beyond logging for diagnostic or telemetry I can see only a possibility of passing the data to NotfoundPage.razor via a service. When we want to display custom content, e.g. "Movie was not found" when NotFound was called on Movie.razor and "User was not found" when called on User.razor. We can call a service that will change the context of the message. CThe community asked about it yesterday but back then, it did not cross my mind. Let me cover it in short snippets

// Router.razor

@inject NotFoundContextService NotFoundContext

<Router AppAssembly="typeof(Program).Assembly">
    <Found Context="routeData">
        <RouteView RouteData="routeData" DefaultLayout="typeof(Layout.MainLayout)" />
        <FocusOnNavigate RouteData="routeData" Selector="h1" />
    </Found>
    <NotFound>
        <LayoutView Layout="typeof(Layout.MainLayout)">
            <h1>@(NotFoundContext.Context) Not Found</h1> 
            <h3>DynamicNotFoundPage</h3>
            <div>
                <p>@(NotFoundContext.CustomMessage ?? "Sorry, the page you requested could not be found")</p>
                </div>
        </LayoutView>
    </NotFound>
</Router>

// Movie.razor

@inject MovieService MovieService
@inject NavigationManager NavigationManager
@inject NotFoundContextService NotFoundContext

protected override async Task OnInitializedAsync()
    {
        NavigationManager.OnNotFound += HandleNotFound;
        movie = await MovieService.GetMovieByIdAsync(id);

        if (movie == null)
        {
            NavigationManager.NotFound();
        }
    }

    private void HandleNotFound(object? sender, NotFoundEventArgs e)
    {
        NotFoundContext.UpdateContext("Movie", "The requested movie was not found");
    }

    public void Dispose()
    {
        NavigationManager.OnNotFound -= HandleNotFound;
    }

// User.razor

    protected override async Task OnInitializedAsync()
    {
        NavigationManager.OnNotFound += HandleNotFound;
        movie = await UserService.GetUserByIdAsync(id);

        if (movie == null)
        {
            NavigationManager.NotFound();
        }
    }

    private void HandleNotFound(object? sender, NotFoundEventArgs e)
    {
        NotFoundContext.UpdateContext("User", "The requested user was not found");
    }

    public void Dispose()
    {
        NavigationManager.OnNotFound -= HandleNotFound;
    }

// NotFoundContextService.cs

    public class NotFoundContextService
    {
        public string Context { get; private set; } = "General";
        public string CustomMessage { get; private set; } = "The requested resource was not found";

        public void UpdateContext(string context, string customMessage)
        {
            Context = context;
            CustomMessage = customMessage;
        }
    }

[guardrex]

Fantastic! 🎉 ... I'll place that on a PR this afternoon and ping you on it for review.

UPDATE: It will be tomorrow (Thursday). I got bogged down in other work today ⛰️⛏️😅.

[ilonatommy]

I don't remember where but you asked somewhere if OnNotFound event gets fired when we just set HttpContextAccessor.HttpContext.Response.StatusCode = 404 without calling navigationManager.NotFound(). I just double checked and it's not triggered.