Make it easy to transition from stateful prerendering to -> non-stateful prerendering

I think we need to come up with a strategy or some diagnostics to help people migrate from the preview 7 template to the preview 8 one.

Since we’re removing stateful prerendering, there are two changes you need to make in your app:

• In _Host.cshtml use RenderStaticComponentAsync
• In Startup.cs add a mapping for the component to the <app> element

Before

app.UseEndpoints(endpoints =>
{
    endpoints.MapBlazorHub();
    endpoints.MapFallbackToPage("/_Host");
});

After

app.UseEndpoints(endpoints =>
{
    endpoints.MapBlazorHub<App>("app");
    endpoints.MapFallbackToPage("/_Host");
});

---

The problem is that it’s really easy to get the first one of these right - but once you do, the app stops responding. You’ll prerender just fine, but no websocket will be opened. There are literally NO diagnostics telling you that you forgot to do the second part of this.

We need to consider whether we have any good ideas to help people understand how to update preview 4->preview 8

[stavroskasidis]

You must also consider multiple “entry point” components for existing MVC/Razor pages projects. For example:

I have a razor page Index.cshtml, and I want to render a component in there, for example

<counter>@(await Html.RenderStaticComponentAsync<Counter>())</counter>

while having a second page called Whatever.cshtml, in which I want to render a different component in there, like:

<whatever-component>@(await Html.RenderStaticComponentAsync<WhateverComponent>())</whatever-component>

Currently in preview 7 everything works fine when using

endpoints.MapBlazorHub();

How will this work after the changes ?

[stavroskasidis]

Issue created: https://github.com/aspnet/AspNetCore/issues/12795

😀