Application State in BlazorApp .Net 8

[vconfrence]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

using cascading values and local storage for application state doesn't seem to work in blazor web app .net 8
cc: @guardrex dotnet/AspNetCore.Docs#31316

Expected Behavior

LocalStorage, renderfragment element of the cascadingAppState component seem to be null.

Steps To Reproduce

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

Exceptions (if any)

No response

.NET Version

8

Anything else?

No response

[guardrex]

Thanks @vconfrence ... I'll keep an 👁️ on this. If there's doc work to do, we'll hear on this issue after you chat with the PU about your problem. Note that most folks are on holiday 🎆 vacation, so it could take a short while for this issue to be reached.

[javiercn]

@vconfrence thanks for contacting us.

Your repro doesn't have any code other than the initial template.

Hi @vconfrence. We have added the "Needs: Author Feedback" label to this issue, which indicates that we have an open question for you before we can take further action. This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.

[vconfrence]

Inside the counter page the button click triggers a call to the set property of the CascadingAppState which shows the LocalStorageService, ChildContent to be NULL and throws an exception when StateHasChanged() gets called.

Here's what's embedded in the counter page

@page "/counter"

Counter

Counter

Current count: @currentCount

<button class="btn btn-primary" @OnClick="IncrementCount">Click me

@code {
[CascadingParameter] public BlazorApp1.Client.Components.CascadingAppState AppState { get; set; }
private int currentCount = 0;

private void IncrementCount()
{
    //var json = System.Text.Json.JsonSerializer.Serialize(appstate);
    AppState.SetProperty(this, "IsDevelopment", true, false);
    currentCount++;
}

}

[guardrex]

@vconfrence ... To place code in an issue comment use triple-backticks with a code language on a line above the code (```razor) and triple-backticks on a line below (```). It will format the code if you do that ☝️.

[vconfrence]

Any suggestion to the stated issue would be greatly appreciated.

[vconfrence]

Hi everyone. any suggestions/comments regarding the described issue?

[SteveSandersonMS]

@vconfrence I think there's some confusion between DI services and cascading values. These are two separate concepts. Just because you've registered a cascading value of type CascadingAppState does not mean there is any DI service of that type.

You can register and consume that type as a cascading value if you want, but then you're not using DI, and hence the system isn't going to resolve other dependencies like @inject ILocalStorageService LocalStorageService for you.

Alternatively, and more simply, I'd recommend changing CascadingAppState to be a regular DI service (not a Blazor component) and registering it in DI. Then you can @inject it into your other Blazor components, and all its DI dependencies will be resolved by the system.