Xaf valueManager doesn't work in mIddleware

Thanks a lot! It helped me use my helper with the value manager in platform independent module as before!
And for middleware I used InitialState data as specified in your answer.

App.razor

C#
@code {
    [Parameter]
    public InitialApplicationState InitialState { get; set; }
    protected override void OnInitialized()
    {
        InitialApplicationStorage.Host = InitialState.Host;
        //InitialApplicationStorage.RequestParams = InitialState.RequestParams;
        InitialApplicationStorage.PhysicalApplicationPath = InitialState.PhysicalApplicationPath;

        // Init AppSetupHelper (singleton using ValueManager)
        AppSetupHelper.Instance.Init(
            () => InitialState.Host,
            () => null,
            () => InitialState.PhysicalApplicationPath);

        base.OnInitialized();
    }
}

Hello again
After update to 21.2.4 I have problem with value manager. Now at App.razor on get ValueManager.GetValueManager<AppSetupHelper>(nameof(AppSetupHelper)) I have "ValueManagerContext.Storage is null." exception.
Call from App.razor

Code
@code {
    [Parameter]
    public InitialApplicationState InitialState { get; set; }
    protected override void OnInitialized()
    {
        InitialApplicationStorage.Host = InitialState.Host;
        //InitialApplicationStorage.RequestParams = InitialState.RequestParams;
        InitialApplicationStorage.PhysicalApplicationPath = InitialState.PhysicalApplicationPath;


        // Init AppSetupHelper
        AppSetupHelper.Instance.Init(
            () => InitialState.Host,
            () => null,
            () => InitialState.PhysicalApplicationPath);
// Call under Instance getter: ValueManager.GetValueManager<AppSetupHelper>(nameof(AppSetupHelper)).Value == null


        base.OnInitialized();
    }
}

How can I resolve it?

Hello,

In some cases, ValueManager was initialized even if XAF was not in use, and this led to issues - for example: XAF Blazor "Cannot override storage" error after updating to 21.2.3. In v21.2.4, ValueManager is initialized when an XafApplication instance is accessed. To ensure that ValueManager is initialized properly, it is possible to call GetApplication of the IXafApplicationProvider service:

Razor
...
@inject DevExpress.ExpressApp.Blazor.Services.IXafApplicationProvider applicationProvider
...
@code {
    protected override void OnInitialized() {
        applicationProvider.GetApplication();
        ...
    }
}

P.S. I recommend you avoid using ValueManager and use services instead as described in the answer.

Thanks,
Ilya P

I cannot find how to use blazor service in business logic in platform independent module, but your answer was helpful for me and I resolved the problem, thank you.

Helllo again.
Not sure is it value manager problem so maybe it should be in a new topic, but I got it from my related code. I discovered reports doesn't open anymore in my system. This happens because on report opening a new blazor application creating and I use subdomain there to fix connection string to support multitenant. But my InitialApplicationStorage is void in this case. I fixed the sample: to reproduce the issue just create and open a report and check SampleBlazorApplication.OnSetupStarted method in debug. I left a comment there.

Hi Andrey,

Thank you for the project. I see that your InitialApplicationStorage is recreated when a report is opened. Currently, I don't have a solution for this issue. Please allow us additional time to research this behavior. We will update this ticket once we have news.

Hello,

Thank you for your patience. This behavior is specific to the Reports V2 Blazor module. Internally, a separate IServiceScope is created for a report. In your case, the InitialApplicationStorage service belongs to this separate scope that is why it is not initialized. It is possible to use an AsyncLocal storage to pass parameters. For example, in the following way:

1. In the HttpContextMiddleware class, define a storage and initialize its value:

C#
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;

namespace Sample.Blazor.Server {
    public class HttpContextMiddleware {
        private static AsyncLocal<string> hostStaticStorage = new AsyncLocal<string>();
        private static AsyncLocal<string> physicalApplicationPathStaticStorage = new AsyncLocal<string>();
        private readonly RequestDelegate next;
        private readonly IWebHostEnvironment env;
        public HttpContextMiddleware(RequestDelegate next, IWebHostEnvironment env) {
            this.next = next;
            this.env = env;
        }
        public static string Host => hostStaticStorage.Value;
        public static string PhysicalApplicationPath => physicalApplicationPathStaticStorage.Value;
        public async Task InvokeAsync(HttpContext httpContext, InitialApplicationStorage initialApplicationStorage) {
            initialApplicationStorage.Host = $"{httpContext.Request.Scheme}://{httpContext.Request.Host}";
            initialApplicationStorage.PhysicalApplicationPath = env.ContentRootPath;
            hostStaticStorage.Value = initialApplicationStorage.Host;
            physicalApplicationPathStaticStorage.Value = initialApplicationStorage.PhysicalApplicationPath;
            await this.next(httpContext);
        }
    }
}

2. Use it in your application's OnSetupStarted method:

C#
public partial class SampleBlazorApplication : BlazorApplication {
    protected override void OnSetupStarted() {
        base.OnSetupStarted();
        // Init AppSetupHelper and use to get connection string
        var initialApplicationStorage = ServiceProvider.GetRequiredService<InitialApplicationStorage>();
        AppSetupHelper.Instance.Host = initialApplicationStorage.Host ?? HttpContextMiddleware.Host;
        AppSetupHelper.Instance.PhysicalApplicationPath = initialApplicationStorage.PhysicalApplicationPath ?? HttpContextMiddleware.PhysicalApplicationPath;
        ...
    }
    ...
}

I hope you find this information helpful.

Thanks,
Ilya P

Thanks. Is it possible to drop using of initialApplicationStorage and initialApplicationState and use AsyncLocal only?