httpcontextaccessor null reference on app service but not debug - azure

Question

I have a weird issue I can't explain.
I have a helper class in my Blazor Server Side app that does arb functions for my app. I added services.AddHttpContextAccessor(); in startup,
declared it in my helper class
public GlobalHelper(IHttpContextAccessor accessor,
IOptions<AzureADB2COptions> azureAdB2COptions,
IConfiguration configuration
)
{
_accessor = accessor;
AzureAdB2COptions = azureAdB2COptions.Value;
Configuration = configuration;
}
and then have a function to return the userid:
public string GetUserID()
{
var context = _accessor.HttpContext;
return context.User.FindFirst(ClaimTypes.NameIdentifier).Value;
and then in my page, I just want to display it first on a button click event:
#inject Classes.GlobalHelper _helper
<h1>Counter</h1>
<p>Current count: #currentCount</p>
<button class="btn btn-primary" #onclick="IncrementCount">Click me</button>
#code {
string currentCount = "test";
void IncrementCount()
{
var test4 = httpContextAccessor.HttpContext;
var authState = AuthenticationStateProvider.GetAuthenticationStateAsync();
var user = authState.Result.User;
if (user.Identity.IsAuthenticated)
{
try
{
currentCount = _helper.GetUserID().Result;
}
catch (Exception ex)
{
currentCount = ex.ToString();
}
}
else
{
Console.WriteLine("The user is NOT authenticated.");
}
}
}
If I just debug locally, this works fine. As soon as I publish this to an app service in Azure... I get a nullreferenceexception on accessing the httpcontextaccessor in the globalhelper class. This line:
return context.User.FindFirst(ClaimTypes.NameIdentifier).Value;
What could I be doing wrong so that the httpcontext is null in the app service and not in debug on my local machine?

Answer 1

The HttpContext is not available, at least most of the time, in Blazor Server App. You shouldn't try to access it, and you shouldn't use IHttpContextAccessor. Read more here:
https://github.com/aspnet/AspNetCore/issues/14090
https://github.com/aspnet/AspNetCore/issues/13903
https://github.com/aspnet/AspNetCore/issues/12432#issuecomment-534315513
https://github.com/aspnet/AspNetCore/issues/5330#issuecomment-413928731
Note: You may access Authentication State in Blazor Server App via the AuthenticationStateProvider object and authorization components such as AuthorizeView, AuthorizeRouteView and CascadingAuthenticationState depending on what you want to do.