NullReferenceException when clicking on a product from home page

[MaherJendoubi]

Hi friends,

I am using Visual Studio 15.8.4.
dotnet --version : 2.2.100-preview2-009404

System.NullReferenceException: Object reference not set to an instance of an object.
at SimplCommerce.Module.Localization.TagHelpers.LanguageDirectionTagHelperComponent.Process(TagHelperContext context, TagHelperOutput output) in C:\Users\Maher\Documents\GitHub\SimplCommerce\src\Modules\SimplCommerce.Module.Localization\TagHelpers\LanguageDirectionTagHelperComponent.cs:line 26
at Microsoft.AspNetCore.Razor.TagHelpers.TagHelperComponent.ProcessAsync(TagHelperContext context, TagHelperOutput output)
at Microsoft.AspNetCore.Mvc.Razor.TagHelpers.TagHelperComponentTagHelper.ProcessAsync(TagHelperContext context, TagHelperOutput output)
at Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner.RunAsync(TagHelperExecutionContext executionContext)
at AspNetCore.Views_Shared__Layout.ExecuteAsync()
at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage page, ViewContext context)
at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage page, ViewContext context, Boolean invokeViewStarts)
at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderLayoutAsync(ViewContext context, ViewBufferTextWriter bodyWriter)
at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context)
at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable1 statusCode) at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ActionContext actionContext, IView view, ViewDataDictionary viewData, ITempDataDictionary tempData, String contentType, Nullable1 statusCode)
at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewResultExecutor.ExecuteAsync(ActionContext context, ViewResult result)
at Microsoft.AspNetCore.Mvc.ViewResult.ExecuteResultAsync(ActionContext context)
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeResultAsync(IActionResult result)
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResultFilterAsyncTFilter,TFilterAsync
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResultExecutedContext context)
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeResultFilters()
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
at Microsoft.AspNetCore.Localization.RequestLocalizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.MigrationsEndPointMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

[hishamco]

I can confirm the bug and i'm working on it now
thanks

[hishamco]

As I see the issue come from the that Features in Features.Get<IRequestCultureFeature>() it returns a null

[hishamco]

After a lot of investigation I come up with the following:
1- This is not occur on the products page only, it occurs for all the requests after the first one
2- Strange part is IRequestCultureFeature isn't available in LanguageDirectionTagHelperComponent while it's available in views for instance _SelectLanguagePatial

this may occurs because:

• The localization setup has an issue
• Middlewares order
• Module architecture
• Or a bug

your thought @thiennn

[hishamco]

I can confirm now it's an MVC bug, so I will open an issue there

[MaherJendoubi]

It's strange when you run Ctrl+F5 this bug disappears.

[hishamco]

It's strange when you run Ctrl+F5 this bug disappears

Strange!! but still there's MVC localization issue bug

[hishamco]

I tried another way to use IWorkContext to get the current user culture, but it throws an exception, because the User for first time is null

Now either move the code into the views temporary, so no one is blocking or think about alternative solution

[thiennn]

If you change from Singleton to Transient for LanguageDirectionTagHelperComponent registration. The problem disappear

[hishamco]

AFAIK the TagHelperComponent should be registered as singleton, so let us keep this open for track the issue that I filed in the MVC repo

[MaherJendoubi]

Thank you @hishamco @thiennn for your answers.

[hishamco]

@MaherJendoubi I think we should make this open to track the MVC issue