Update dotnet-8 KeyedSevice

[WeihanLi]

Summary

• Update to IServiceProvider since there's no IKeyedServiceProvider registered
• Update the SmallCacheConsumer to get cache value instead of returning the IMemoryCache

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docs/core/whats-new/dotnet-8.md	What's new in .NET 8

[gewarren]

@ericstj Can you review this?

[ericstj]

Looks like this sample still doesn't work. Seems the BigCache and SmallCache types are still missing? perhaps those were meant to be https://github.com/dotnet/AspNetCore.Docs.Samples/blob/d23c059e7e88a4151ab4adbf5a56d27dc4d726c9/samples/WebKeyedService/ICache.cs#L1C1-L13C2 as ICache?

Here's an update that works for me https://gist.github.com/ericstj/efd848d65ba6591546a2707897cad8fa. I'm not entirely sure if this communicates the concepts as cleanly. @steveharter @benjaminpetit what do you think?

[WeihanLi]

Oh yeah, thanks for the careful review @ericstj
it is, I only focused on the KeyedService usage, not trying to run up the sample code, my bad
updated sample code according to your gist code and verified it works, thanks very much

[ericstj]

Thank you for the fix here. That original sample was something we copied from a tweet - not surprised it had multiple issues 😆. I would like either @steveharter or @benjaminpetit to weigh in on this before we merge.

[benjaminpetit]

I think we should also show that you can use the FromKeyedServices attribute directly in the MapGet method:

app.MapGet("/big", ([FromKeyedServices("big")] ICache cache) => cache.Get("data"));

But also showing the attribute usage in the constructor is important. So maybe we could so one of each, if that's not too weird?

[WeihanLi]

Make sense, how about adding the following two examples?

app.MapGet("/big-cache", ([FromKeyedServices("big")] ICache cache) => cache.Get("data"));
app.MapGet("/small-cache", (HttpContext httpContext) => httpContext.RequestServices.GetRequiredKeyedService<ICache>("small").Get("data"));

[benjaminpetit]

Yes that would be great!

[ericstj]

LGTM - also tested this in a web project and all is working well