BlazorWebApp .Net 8 App State management

[vconfrence]

Description

Following Carl Franklin's application state management in blazor doesn't seem to work in .Net 8.

https://www.youtube.com/watch?v=4WPuGwxZKIA

The local storage instance and the renderfragment appear to be null. in addition getting The render handle is not yet assigned when calling statehaschanged() in the cascading app state throws the following exception "The render handle is not yet assigned."

Here's the github repo the project

https://github.com/vconfrence/BlazorApp1.git

CascadingAppState component which is meant to be a root level cascading value available through cascading parameter within any compoenent doesn't seem to work. LocalStorage and other variables don't seem to be initializing.

Also followed guidelines posted by Microsoft which didn't work

https://learn.microsoft.com/en-us/aspnet/core/blazor/components/cascading-values-and-parameters?preserve-view=true&view=aspnetcore-8.0#root-level-cascading-values

https://learn.microsoft.com/en-us/aspnet/core/blazor/state-management?view=aspnetcore-7.0&pivots=server#handle-prerendering

Page URL

https://learn.microsoft.com/en-us/aspnet/core/blazor/state-management?view=aspnetcore-8.0

Content source URL

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/blazor/state-management.md

Document ID

e5e1273b-195e-5da1-b4aa-66bbcff1425b

Article author

@guardrex

[github-actions]

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This issue has been marked for triage on the Blazor Docs GitHub project, and I'll respond as soon as I return from the holiday vacation the second week of January.

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[guardrex]

Carl Franklin's application state management in blazor

We can't support third-party content for Blazor, so that would need to be taken up with him.

Also followed guidelines posted by Microsoft which didn't work

Root-level cascading values do work (and that is the correct version of the article). The approaches described and the examples are functional AFAIK. You'd need to put up a minimal repro project of the behavior that you're describing. If you can't get our guidance to work, open an issue for the product unit at ...

https://github.com/dotnet/aspnetcore/issues

... and cross-link your minimal repro project so they can see what you're doing.

Please add ...

cc: @guardrex https://github.com/dotnet/AspNetCore.Docs/issues/31316

... to the bottom of your opening comment so that I can follow along. I might re-open this for doc work depending on what they say.

https://learn.microsoft.com/en-us/aspnet/core/blazor/state-management?view=aspnetcore-7.0&pivots=server#handle-prerendering

You're looking at the wrong version of the article. Change your doc version selector to 8.0 for this version of the guidance ...

https://learn.microsoft.com/en-us/aspnet/core/blazor/state-management?view=aspnetcore-8.0&pivots=server#handle-prerendering

[vconfrence]

Appreciate the comments. Here's the repo containing an example which shows root level cascading not working.
https://github.com/vconfrence/BlazorApp1.git

[vconfrence]

Hi everyone. any suggestions/comments would be greatly appreciated.

[guardrex]

It looks like you followed the guidance correctly. The product unit will need to investigate on the PU issue that you opened. I'm 👂 over there for how it turns out. The reason that responses are so slow right now is that they have a large backlog of Blazor Web App/8.0 issues to address. Hopefully, they'll reach your issue soon.

[guardrex]

I see Steve just responded. That's kind'a challenging to get into a thumbnail remark, but I'm distilling it down to something like ...

Registering a cascading value doesn't register services or activate DI for the registered type. Treat services separately from cascading values, registering them separately from the cascading value and injecting them where the cascading value is consumed.

... 🤔 something like that 😆.

[guardrex]

... but 🤔 .........

https://learn.microsoft.com/en-us/aspnet/core/blazor/state-management?view=aspnetcore-8.0&pivots=server#factor-out-the-state-preservation-to-a-common-location

Hummmmmmmm ... I need to look at that a little closer compared to what you did.

[guardrex]

Idk @vconfrence ... did you not register ILocalStorageService ... is that something that the Blazored services register? It kind'a seems like compared to the state preservation approach that your code would work in spite of what Steve said. It's clearly a very similar approach.

[guardrex]

I'll wait to see if Steve reacts to my remark on the PU issue. The best I can do thus far in terms of a doc update is ...

On its own, registering a cascading value doesn't register additional services that the cascaded type uses. Treat required services separately from cascading values, registering them separately from the cascaded type.

... but like I said ... that doesn't really address the problem that you ran into. AFAICT, you did that already and already knew that. 😄

[guardrex]

Ok ... getting closer to something that I can cover, but it looks like we still don't have an answer on wrapping the Router with the component. That is actually just like what we show.

[guardrex]

Latest stab 🔪 at text would be something like ...

Registering a component type as a root-level cascading value doesn't register additional services or permit service activation in the component. Treat required services separately from cascading values, registering them separately from the cascaded type. Wrap the Router in the Routes component or the Routes component in the App component with the component registered as the cascading value, and avoid using AddCascadingValue to register the component type.

... and I see a bit of text that I need to update separately in the 8.0 state management doc, where it states ...

To make the state accessible to all components in an app, wrap the CounterStateProvider component around the Router in the App component (App.razor):

That needs to be updated for 8.0.

... AND I need to place a cross-link from the Cascading values and params article to the State management article in an Additional resources section added to the doc.