HttpContext property of HttpContextAccessor is null

Question

HttpContext property of HttpContextAccessor is null

cosmin-ciuc opened this issue 6 years ago · comments

I have a REST API web application which worked perfectly with ASP.Net Core 2.1. Now the constructor injected IHttpContextAccessor returns a null value for HttpContext property.

In Startup.cs class, in ConfigureServices method I have:

services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();          
services.AddScoped<WorklistPagedTasksHalRepresentationConverter>();

This is the WorklistPagedTasksHalRepresentationConverter class

public class WorklistPagedTasksHalRepresentationConverter : TypeConverter<WorklistWithPagedTasks, WorklistPagedTasksHalRepresentation>
    {
        private readonly IHttpContextAccessor httpContextAccessor;

        private readonly IMapper mapper;

        public WorklistPagedTasksHalRepresentationConverter(IHttpContextAccessor httpContextAccessor, IMapper mapper)
        {
            this.httpContextAccessor = httpContextAccessor;
            this.mapper = mapper;
        }

        public WorklistPagedTasksHalRepresentation Convert(WorklistWithPagedTasks source, WorklistPagedTasksHalRepresentation destination, ResolutionContext context)
        {
            var tasks = mapper.Map<IList<TaskSummaryHalRepresentation>>(source.Tasks.ResultPage.ToList());
            var worklistPagedTasksHalRepresentation = new WorklistPagedTasksHalRepresentation(
                new PaginatedResult<TaskSummaryHalRepresentation>
                {
                    ResultPage = tasks.AsQueryable(),
                    TotalCount = source.Tasks.TotalCount,
                    PageNumber = source.Tasks.PageNumber
                },
                httpContextAccessor.HttpContext.Request)
            {
                Id = source.Id,
                OwnerId = source.OwnerId,
                OwnerName = source.OwnerName
            };
            return worklistPagedTasksHalRepresentation;
        }
    }

The Convert method is called by a controller method.

David Fowler · Answer 1 · Mon Dec 17 2018 13:42:51 GMT+0800 (China Standard Time)

Can you show your controller method? The one that calls this convert method?

Cosmin Petrenciuc · Answer 2 · Mon Dec 17 2018 16:44:31 GMT+0800 (China Standard Time)

Sure I can post the controller method calling the Convert method but it is a little bit more complicated than just that since I'm using Automapper Nuget package to convert from one type instance to another and the Automapper is the one that is actually calling the Convert method.

I was planning to create a simplified project that could be used to replicate this issue.

You need to have the following Nuget package reference:
<PackageReference Include="AutoMapper" Version="8.0.0" />

Then you would need the following classes

   public class AutoMapperConfiguration
   {
        public static void Configure(IMapperConfigurationExpression config)
        {
           config.AddProfile<WorklistMappingProfile>();
        }
   }

    public class WorklistMappingProfile : AutoMapper.Profile
    {
        public WorklistMappingProfile()
        {
            CreateMap<WorklistWithPagedTasks, WorklistPagedTasksHalRepresentation>().ConvertUsing<WorklistPagedTasksHalRepresentationConverter>();
        }
    }

    public class WorklistSummary
    {
        public Guid Id { get; set; }

        public Guid? OwnerId { get; set; }

        public string OwnerName { get; set; }
    }

    public class WorklistWithPagedTasks : WorklistSummary
    {
        public PaginatedResult<TaskSummary> Tasks { get; set; }
    }

    public class PaginatedResult<TEntity>
    {
        public IQueryable<TEntity> ResultPage { get; set; }

        public int TotalCount { get; set; }

        public int PageNumber { get; set; }
    }

    [Serializable]
    public class BaseEntity
    {
        public Guid Id { get; set; }

        public string DisplayName { get; set; }

        public bool Active { get; set; }

        public string HelpTextHref { get; set; }
        
        public int Order { get; set; }
    }

    [Serializable]
    public class TaskSummary : BaseEntity
    {
        public TaskSummary()
        {
        }

        public TaskSummary(string taskLibraryEntryId)
        {
            TaskLibraryEntryId = taskLibraryEntryId;
        }

        public byte Priority { get; set; }

        public string Note { get; set; }

        public bool Reminder { get; set; }

        public DateTime DueAt { get; set; }

        public Guid? OwnerId { get; set; }

        public Guid? SenderId { get; set; }

        public string SenderName { get; set; }

        public string OwnerName { get; set; }
        
        public string SenderUsername { get; set; }

        public string OwnerUsername { get; set; }

        public string CaseId { get; set; }

        public bool Completed { get; set; }

        public string TaskLibraryEntryId { get; set; }

        public DateTime? Created { get; set; }

        public string TaskDefinitionId { get; set; }

        public bool Accessed { get; set; }
    }

    public class TaskSummaryHalRepresentation
    {
        protected readonly HttpRequest httpRequest;

        private string href;

        public TaskSummaryHalRepresentation(HttpRequest httpRequest)
        {
            this.httpRequest = httpRequest;
        }

        [JsonProperty("id")]
        public Guid Id { get; set; }

        [JsonProperty("caseId", NullValueHandling = NullValueHandling.Include)]
        public string CaseId { get; set; }

        [JsonProperty("displayName", NullValueHandling = NullValueHandling.Include)]
        public string DisplayName { get; set; }

        [JsonProperty("active", NullValueHandling = NullValueHandling.Include)]
        public bool Active { get; set; }

        [JsonProperty("dueAt", NullValueHandling = NullValueHandling.Include)]
        public DateTime DueAt { get; set; }

        [JsonProperty("note", NullValueHandling = NullValueHandling.Include)]
        public string Note { get; set; }

        [JsonProperty("priority", NullValueHandling = NullValueHandling.Include)]
        public int Priority { get; set; }

        [JsonProperty("reminder", NullValueHandling = NullValueHandling.Include)]
        public bool Reminder { get; set; }

        [JsonProperty("ownerName", NullValueHandling = NullValueHandling.Include)]
        public string OwnerName { get; set; }

        [JsonProperty("senderName", NullValueHandling = NullValueHandling.Include)]
        public string SenderName { get; set; }

        [JsonProperty("completed", NullValueHandling = NullValueHandling.Include)]
        public bool Completed { get; set; }

        [JsonIgnore]
        public string OwnerUserName { get; set; }

        [JsonIgnore]
        public string SenderUserName { get; set; }

        [JsonProperty("ownerId", NullValueHandling = NullValueHandling.Include)]
        public Guid? OwnerId { get; set; }

        [JsonProperty("senderId", NullValueHandling = NullValueHandling.Include)]
        public Guid? SenderId { get; set; }

        [JsonProperty("created", NullValueHandling = NullValueHandling.Include)]
        public DateTime? Created { get; set; }

        [JsonProperty("accessed")]
        public bool Accessed { get; set; }
        
        [JsonProperty("taskDefinitionId", NullValueHandling = NullValueHandling.Include)]
        public string TaskDefinitionId { get; set; }
    }

    public class HalRepresentationPagedList<TResource> where TResource : class
    {
        private readonly HttpRequest httpRequest;

        private double maxPage;

        public HalRepresentationPagedList(HttpRequest httpRequest)
        {
            ResourceList = new List<TResource>();
            this.httpRequest = httpRequest;
            Count = 0;
        }

        public HalRepresentationPagedList(PaginatedResult<TResource> paginatedResource, HttpRequest httpRequest) : this(httpRequest)
        {
            ResourceList = paginatedResource.ResultPage?.ToList() ?? new List<TResource>();
            Count = ResourceList.Count();
            Total = paginatedResource.TotalCount;
            Page = paginatedResource.PageNumber;
        }

        [JsonIgnore]
        public int Page { get; }

        [JsonIgnore]
        public int InitialCount { get; set; }

        [JsonIgnore]
        public bool HasDefaultCount { get; set; }

        [JsonIgnore]
        public int DefaultCount { get; set; }

        [JsonProperty("count")]
        public int Count { get; }

        [JsonProperty("pageSize")]
        public int PageSize { get; set; }

        [JsonProperty("total")]
        public int Total { get; }

        public virtual List<TResource> ResourceList { get; set; }

        [JsonIgnore]
        public List<KeyValuePair<string, string>> QueryParams { get; }
    }

    public sealed class WorklistPagedTasksHalRepresentation : HalRepresentationPagedList<TaskSummaryHalRepresentation>
    {
        public WorklistPagedTasksHalRepresentation(PaginatedResult<TaskSummaryHalRepresentation> paginatedTasks, HttpRequest httpRequest) : base(paginatedTasks, httpRequest)
        {
        }

        [JsonProperty("id")]
        public Guid Id { get; set; }

        [JsonProperty("ownerName", NullValueHandling = NullValueHandling.Include)]
        public string OwnerName { get; set; }

        [JsonProperty("ownerId", NullValueHandling = NullValueHandling.Include)]
        public Guid? OwnerId { get; set; }

        [JsonProperty("tasks")]
        public override List<TaskSummaryHalRepresentation> ResourceList { get; set; }
    }

    public class WorklistPagedTasksHalRepresentationConverter : ITypeConverter<WorklistWithPagedTasks, WorklistPagedTasksHalRepresentation>
    {
        private readonly IHttpContextAccessor httpContextAccessor;

        private readonly IMapper mapper;

        public WorklistPagedTasksHalRepresentationConverter(IHttpContextAccessor httpContextAccessor, IMapper mapper)
        {
            this.httpContextAccessor = httpContextAccessor;
            this.mapper = mapper;
        }

        public WorklistPagedTasksHalRepresentation Convert(WorklistWithPagedTasks source, WorklistPagedTasksHalRepresentation destination, ResolutionContext context)
        {
            var tasks = mapper.Map<IList<TaskSummaryHalRepresentation>>(source.Tasks.ResultPage.ToList());
            var worklistPagedTasksHalRepresentation = new WorklistPagedTasksHalRepresentation(
                new PaginatedResult<TaskSummaryHalRepresentation>
                {
                    ResultPage = tasks.AsQueryable(),
                    TotalCount = source.Tasks.TotalCount,
                    PageNumber = source.Tasks.PageNumber
                },
                httpContextAccessor.HttpContext.Request)
            {
                Id = source.Id,
                OwnerId = source.OwnerId,
                OwnerName = source.OwnerName
            };
            return worklistPagedTasksHalRepresentation;
        }
    }

    public class WorklistPostInput
    {
        public string OwnerUsername { get; set; }

        [JsonProperty("ownerId")]
        public string OwnerId { get; set; }
    }

After that in ConfigureServices method of your Startup class you need to add the following code:

services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.AddScoped<WorklistPagedTasksHalRepresentationConverter>();
Mapper.Initialize(AutoMapperConfiguration.Configure);
services.AddSingleton(Mapper.Configuration);
services.AddScoped<IMapper>(
    serviceProvider => new Mapper(serviceProvider.GetRequiredService<AutoMapper.IConfigurationProvider>(), serviceProvider.GetService));

And now the controller method:

    [ApiController]
    [Route("fs/rest/worklists")]
    [Produces("application/json")]
    public class WorklistsController : ControllerBase
    {
        private readonly IMapper mapper;

        public WorklistsController(IMapper mapper)
        {
            this.mapper = mapper;
        }

        [HttpPost("")]
        [ProducesResponseType(typeof(WorklistPagedTasksHalRepresentation), (int)HttpStatusCode.Created)]
        public async Task<ActionResult<WorklistPagedTasksHalRepresentation>> PostWorklistAsync([FromBody]WorklistPostInput worklist)
        {
            var newWorklist = new WorklistWithPagedTasks();
            if (worklist != null)
            {
                if (!string.IsNullOrWhiteSpace(worklist.OwnerId))
                {
                    Guid.TryParse(worklist.OwnerId, out var ownerid);
                    newWorklist.OwnerId = ownerid; 
                }
            }

            newWorklist.Tasks = new PaginatedResult<TaskSummary> { PageNumber = 1, ResultPage = new List<TaskSummary>().AsQueryable(), TotalCount = 0 };
            var worklistHalRepresentationPaged = mapper.Map<WorklistPagedTasksHalRepresentation>(newWorklist);
            return Created("myUrl", worklistHalRepresentationPaged);
        }
    }

Cosmin Petrenciuc · Answer 3 · Mon Dec 17 2018 20:49:20 GMT+0800 (China Standard Time)

I've done some more tests. It seems that if you alter the value of HttpContext.TraceIdentifier property in a middleware, the HttpContextAccessor.HttpContext property will become null.

I'm attaching a sample web application which can be used to reproduce the error. If you'll make the following HTTP request:

POST http://localhost:65448/api/worklists HTTP/1.1
X-Correlation-ID: 80000024-0007-fa00-b63f-84710c7967bc
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36 Edge/17.17134
accept: application/json
content-type: application/json
Accept-Language: en-US,en;q=0.8,nb;q=0.6,ro-RO;q=0.4,ro;q=0.2
Accept-Encoding: gzip, deflate
Connection: Keep-Alive
Host: localhost:65448
Content-Length: 0

you'll reproduce the error.

WebApplication1.zip

Cosmin Petrenciuc · Answer 4 · Mon Dec 17 2018 22:06:10 GMT+0800 (China Standard Time)

@davidfowl: I have made another web application project, even simpler, that can be used to reproduce the problem. I am 100% convinced that if you alter the HttpContext.TraceIdentifier from the middleware code you force HttpContextAccessor instance to set its HttpContext property to null.

Please see the attached sample application.
WebApplication2.zip

If you call GET api/values without specifying the HTTP header X-Correlation-ID everything works fine. But if you make the following request:

GET http://localhost:60065/api/values HTTP/1.1
X-Correlation-ID: myCorrelationId
accept: application/json
Accept-Language: en-US,en;q=0.8,nb;q=0.6,ro-RO;q=0.4,ro;q=0.2
Host: localhost:60065

the HttpContext property of IHttpContextAccessor becomes null. This happens because in CurrentRequestMiddleware I'm setting the value of HttpContext.TraceIdentifier to the value of X-Correlation-ID header.

Thank you.

Kieron Lanning · Answer 5 · Mon Dec 17 2018 22:18:27 GMT+0800 (China Standard Time)

@cosmin-ciuc Thanks for investigating that - I've had exactly the same problem, but haven't had a chance to figure out why it's happening.

I've delayed our upgrade to 2.2 because of this exact problem.

Cosmin Petrenciuc · Answer 6 · Mon Dec 17 2018 22:29:51 GMT+0800 (China Standard Time)

You're welcome @kieronlanning.

Cosmin Petrenciuc · Answer 7 · Mon Dec 17 2018 23:29:22 GMT+0800 (China Standard Time)

I would try to fix this problem myself but it's going to take me a while until I familiarize myself with the projects and classes structure. I think it would be much more efficient if the developers of ASP.NET Core 2.2 would look into the issue and they would make a fix for it.

David Fowler · Answer 8 · Tue Dec 18 2018 00:14:02 GMT+0800 (China Standard Time)

Yes this is a change made in 2.2. It’s fixed in 3.0, maybe we should backport that’s change to 2.2.x.

cc @muratg

Murat Girgin · Answer 9 · Tue Dec 18 2018 00:48:46 GMT+0800 (China Standard Time)

@davidfowl where's the fix in master?

Kieron Lanning · Answer 10 · Tue Dec 18 2018 01:19:00 GMT+0800 (China Standard Time)

@davidfowl / @muratg We 100% need this fix back ported, please!

Chris Ross · Answer 11 · Tue Dec 18 2018 01:27:02 GMT+0800 (China Standard Time)

Here's the regression: 0f4f195

Here's the 3.0 fix: 49d785c

Murat Girgin · Answer 12 · Tue Dec 18 2018 01:31:48 GMT+0800 (China Standard Time)

@davidfowl Are you able to send a 2.2.2 PR?

David Fowler · Answer 13 · Tue Dec 18 2018 01:38:26 GMT+0800 (China Standard Time)

No I’m on vacation, have somebody backport the PR 😬

Murat Girgin · Answer 14 · Tue Dec 18 2018 01:42:12 GMT+0800 (China Standard Time)

@davidfowl Since 2.2.1 is done, earliest this can go in is 2.2.2. Plenty of time in January to do it. Please make sure to fill out the shiproom template.

Murat Girgin · Answer 15 · Wed Dec 19 2018 00:56:28 GMT+0800 (China Standard Time)

@JunTaoLuo Could you prepare this for 2.2.2 please?

Work is backporting Ben's PR from master and filling out the shiproom template.

Kieron Lanning · Answer 16 · Wed Jan 16 2019 03:27:21 GMT+0800 (China Standard Time)

@JunTaoLuo Is there an ETA for GA? Thanks!

Murat Girgin · Answer 17 · Wed Jan 16 2019 03:29:44 GMT+0800 (China Standard Time)

@kieronlanning Should be sometime in February.

Kieron Lanning · Answer 18 · Wed Jan 16 2019 03:44:54 GMT+0800 (China Standard Time)

@muratg Thanks!

Tom Robinson · Answer 19 · Thu Jan 24 2019 01:00:14 GMT+0800 (China Standard Time)

Worth adding a mention on the known issues page? https://github.com/dotnet/core/blob/master/release-notes/2.2/2.2-known-issues.md

rajesh-rajendran-ascendlearning-com · Answer 20 · Mon Jan 28 2019 22:55:06 GMT+0800 (China Standard Time)

Will this issue be fixed sometime by February? Is my understanding right ?
Right now we have upgraded to Aps.NetCore 2.2 and we are experiencing this issue, so do you think we need to downgrade to 2.1.7 ?

John Luo · Answer 21 · Tue Jan 29 2019 02:13:38 GMT+0800 (China Standard Time)

Correct, the fix will be released in February. Downgrading to 2.1 is also possible to work around the issue.

Chris Paynter · Answer 22 · Sat Feb 02 2019 21:38:55 GMT+0800 (China Standard Time)

Looking forward to this fix!

Fernando Nunes · Answer 23 · Fri Feb 08 2019 00:14:21 GMT+0800 (China Standard Time)

We have a solution that uses X-Correlation-ID and we need to set the TraceIdentifier badly.
Hope this gets fixed on 2.2.2.

Murat Girgin · Answer 24 · Fri Feb 08 2019 00:59:38 GMT+0800 (China Standard Time)

@FernandoNunes it's coming in a week or so :)

Fernando Nunes · Answer 25 · Fri Feb 08 2019 01:16:55 GMT+0800 (China Standard Time)

@muratg Thats great news, however we do are in a migration process and we did found a workaround after looking at how the "issued" HttpContextAcessor is implemeted, so we inject the HttpContextAcessor when we affect the TraceIdentifier and imediatly reset it so that it is available for the rest of the HttpRequest execution. We don't see any side-effects and after preliminary tests, seems a suitable workaround while we don't have 2.2.2 ready.

public class CorrelationIdMiddleware
{
    private readonly RequestDelegate _next;
    private readonly IHttpContextAccessor _httpAccessor;

    public CorrelationIdMiddleware(RequestDelegate next, IHttpContextAccessor httpAccessor)
    {
        _next = next;
        _httpAccessor = httpAccessor;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        if (context.Request.Headers.ContainsKey("X-Correlation-ID"))
        {
            context.TraceIdentifier = context.Request.Headers["X-Correlation-ID"];
            // WORKAROUND: On ASP.NET Core 2.2.1 we need to re-store in AsyncLocal the new TraceId, HttpContext Pair
            _httpAccessor.HttpContext = context;
        }

        // Call the next delegate/middleware in the pipeline
        await _next(context);
    }
}

Hope this helps.

Best Regards,
Fernando Nunes

Andrii Kovtun · Answer 26 · Mon Feb 11 2019 22:59:02 GMT+0800 (China Standard Time)

_httpAccessor.HttpContext = context;

Thank you @FernandoNunes!
Faced the same issue in my current project.
Your shared solution was very useful. It's simple and works.
Moreover, it was provided at a very actual time.

Adam Schueller · Answer 27 · Thu Feb 14 2019 09:20:16 GMT+0800 (China Standard Time)

@muratg not sure if you guys are planning to backport the fix further, but just a heads up: this exact same issue is present in v2.1.X as well. All the documentation on the bug I've seen assumes it started in 2.2.0 (e.g., one of the packages we're using: https://github.com/stevejgordon/CorrelationId#known-issue-with-aspnet-core-220) but we've confirmed the same behavior in several versions:

2.1.0 : OK
2.1.1, 2.1.2 : Untested
2.1.3 : Bug present
2.1.4, 2.1.6 : Untested, assuming is present
2.1.7 (latest stable 2.1.X) : Bug present

Luckily @FernandoNunes's workaround works on those versions as well 👍

Murat Girgin · Answer 28 · Thu Feb 14 2019 09:36:02 GMT+0800 (China Standard Time)

Folks, 2.2.2 (with the fix) was released yesterday!

@AdamSchueller thanks for the update. @davidfowl were you aware that this is broken in 2.1.x as well?

David Fowler · Answer 29 · Thu Feb 14 2019 09:49:50 GMT+0800 (China Standard Time)

It’s not broken in 2.1 AFAIK. Would love a fully isolated repro. Even stranger is that the above claims it was broken in a 2.1 patch which seems unlikely (unless we backported it to a patch). Moving to mondo repo makes it hard to track these changes.

Adam Schueller · Answer 30 · Sat Feb 16 2019 08:05:31 GMT+0800 (China Standard Time)

@davidfowl Apologies, you are correct: the bug is 2.2.0+ only. I was seeing the behavior in our mega-app after we upgraded from ASP.NET to ASP.NET Core 2.1 (ugh). When I tried to recreate in a isolated repo, I could not -- until I added the package references from the app.

The problem was one of the (many) references was silently bumping the version of Microsoft.AspNetCore.Http.dll (where this bug must live) to v2.2.0:

Removing the CookiePolicy reference shows that AspNetCore depends on that assembly as well, but now it's the expected version:

Updating to AspNetCore.App -- which lists an explicit dependency on Microsoft.AspNetCore.Http (>= 2.1.1 && < 2.2.0) -- gives an error that makes it obvious what's happening:

And of course, downgrading the CookiePolicy assembly fixes everything:

I did not mean to cry wolf :) Probably should have tested this outside of a project with 12,000+ files before making any claims. Microsoft.AspNetCore not explicitly declaring a dependency on the assembly with the bug made this trickier to find!

Here's the repo with the issue I was messing around with, just in case (though it's clearly not a bug in 2.1.X): https://github.com/AdamSchueller/HttpContextAccessor-Not-A-Bug

Kayton Parekh · Answer 31 · Sat Feb 16 2019 09:02:26 GMT+0800 (China Standard Time)

We are currently using 2.2.101 SDK with 2.2.0 runtime. I updated my machine to be 2.2.104 SDK and 2.2.2 Runtime. Things seem to work fine when I run my web service and hit it locally, however when I run Integration tests, which set up a TestServer, I run into this failure.

Murat Girgin · Answer 32 · Sat Feb 16 2019 09:18:34 GMT+0800 (China Standard Time)

@parekhkb are you sure you're running 2.2.2 in your test setup?

Kayton Parekh · Answer 33 · Sun Feb 17 2019 01:44:31 GMT+0800 (China Standard Time)

@muratg Yes, the tests are running locally as well. I tried in CI as well and when I upgrade CI to 2.2.2 it fails there as well.

David Fowler · Answer 34 · Sun Feb 17 2019 01:55:54 GMT+0800 (China Standard Time)

@parekhkb Can you provide a minimal repro of the problem?

Chris Ross · Answer 35 · Sun Feb 17 2019 05:49:08 GMT+0800 (China Standard Time)

@parekhkb please open a new issue with the details for your scenario.

Kayton Parekh · Answer 36 · Sun Feb 17 2019 06:12:57 GMT+0800 (China Standard Time)

@Tratcher once I get an isolated Repo I will. Thanks

brandonpollett · Answer 37 · Wed Feb 27 2019 05:00:59 GMT+0800 (China Standard Time)

@Tratcher I believe we have run into a similar issue with TestServer and I opened a new issue with a repro here: #7975

Herb Stahl · Answer 38 · Fri May 10 2019 22:52:25 GMT+0800 (China Standard Time)

@brandonpollett @Tratcher I have a repo case using TestServer. From what I can tell, the HttpContext turns to null after I make an outbound HttpClient call from the app to a REST endpoint in the same app under test. I hope that makes sense. My unit test calls a Rest endpoint on the app and HttpContext is good, then I make an outbound call to another REST endpoint on the same app and when it comes back HttpContext is null.

public async Task<List<TokenExchangeResponse>> ProcessExchangeAsync(TokenExchangeRequest tokenExchangeRequest)
{
// _httpContextAssessor.HttpContext is good
      
            if (tokenExchangeRequest.Extras == null || tokenExchangeRequest.Extras.Count == 0)
            {
                throw new Exception($"{Name}: We require that extras be populated!");
            }
            List<ValidatedToken> validatedIdentityTokens = new List<ValidatedToken>();
            foreach (var item in tokenExchangeRequest.Tokens)
            {
// this following call makes an outbound call to an OAuth2 discovery endpoint to get certs
                var principal = await _tokenValidator.ValidateTokenAsync(new TokenDescriptor
                {
                    TokenScheme = item.TokenScheme,
                    Token = item.Token
                });
// principal is good
// _httpContextAssessor.HttpContext is NULL... ouch!.....
            }
}

Chris Ross · Answer 39 · Fri May 10 2019 23:02:44 GMT+0800 (China Standard Time)

@ghstahl this is a known issue with TestServer and is tracked here: #7975 (comment)

Herb Stahl · Answer 40 · Sat May 11 2019 00:46:25 GMT+0800 (China Standard Time)

@brandonpollett Thank you so much for the workaround code at microsoft/fhir-server#418
@Tratcher looking forward to something going into TestServer. Setting up this workaround would have killed my day had it not been for @brandonpollett and @anurse

Aaron Bauman · Answer 41 · Mon Jun 03 2019 21:17:21 GMT+0800 (China Standard Time)

We are running SDK v2.2.105 and are still seeing this problem.
I believe my injection is wired up correctly

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc();
    services.AddHttpContextAccessor();
    services.AddTransient<IAppIdentity, AppIdentity>();
}

public class AppIdentity : IAppIdentity
{
    private readonly List<Claim> _claims;

    public AppIdentity(IHttpContextAccessor accessor)
    {
        var context = accessor.HttpContext;
        if (context == null)
        {
			throw new ArgumentNullException(nameof(context));
        }

        _claims = context.User?.Claims == null ? new List<Claim>() : context.User.Claims.ToList();
    }
            
    public int AppSourceKey => Convert.ToInt32(_claims.SingleOrDefault(w => w.Type == nameof(AppSourceKey))?.Value);
    public string AppSourceName => _claims.SingleOrDefault(w => w.Type == nameof(AppSourceName))?.Value ?? string.Empty;
}

Here's the SDK's reference on our project

What else should I check?

dillinzser · Answer 42 · Mon Jun 03 2019 21:57:13 GMT+0800 (China Standard Time)

As a simple workaround you can also create your own implementation of IHttpContextAccessor:

namespace MyComponents
{
    public class HttpContextAccessor : IHttpContextAccessor
    {
        private static AsyncLocal<HttpContext> _httpContextCurrent = new AsyncLocal<HttpContext>();

        public HttpContext HttpContext
        {
            get => _httpContextCurrent.Value;
            set => _httpContextCurrent.Value = value;
        }
    }
}

and register that instead:

//services.AddHttpContextAccessor();
services.TryAddSingleton<IHttpContextAccessor, MyComponents.HttpContextAccessor>();

Aaron Bauman · Answer 43 · Mon Jun 03 2019 22:13:57 GMT+0800 (China Standard Time)

@dillinzser Thanks, but HttpContext is still null when I try to access it.

Ashley Stanton-Nurse · Answer 44 · Mon Jun 03 2019 23:12:49 GMT+0800 (China Standard Time)

@Airn5475 can you open a new issue and include a complete runnable sample project? Since this issue is now closed we don't track it as closely and it seems like what you are seeing may be a new problem. We need a complete sample because AsyncLocals can be very dependent on how the code accessing them was launched (see below).

If @dillinzser 's workaround didn't work though, that strongly indicates that something in your app is dumping the AsyncLocal values. Do you have any code in your application that uses ThreadPool.UnsafeQueueUserWorkItem or calls ExecutionContext.SuppressFlow? Both of those would cause AsyncLocal values to be reset in the code that runs inside.

Aaron Bauman · Answer 45 · Tue Jun 04 2019 04:43:45 GMT+0800 (China Standard Time)

@anurse Thanks, I attempted to put together a complete running sample...and it worked fine. I tore apart my project and isolated the issue to Middleware and not doing my injection correctly.

I was passing in a dependency that depended on my aforementioned IAppIdentity into the constructor, when I should have been passing it to the Invoke method.

Posting this to perhaps help someone else.

public class ExceptionMiddleware
{
     private readonly RequestDelegate _next;

     public ExceptionMiddleware(RequestDelegate next /*, IAppLoggingRepository logger*/)
     {
         _next = next;
     }

     public async Task InvokeAsync(HttpContext httpContext, IAppLoggingRepository logger)
     {
         try
         {
             await _next(httpContext);
         }
         catch (Exception ex)
         {
             logger.LogException(ex);
             await HandleExceptionAsync(httpContext, ex);
         }
     }

     //...
}

David Fowler · Answer 46 · Tue Jun 04 2019 05:15:06 GMT+0800 (China Standard Time)

Either should work

Aaron Bauman · Answer 47 · Tue Jun 04 2019 20:46:51 GMT+0800 (China Standard Time)

@davidfowl the constructor level injection doesn't work and I believe the explanation is here:
https://docs.microsoft.com/en-us/aspnet/core/fundamentals/middleware/write?view=aspnetcore-2.2#per-request-dependencies

Because middleware is constructed at app startup, not per-request, scoped lifetime services used by middleware constructors aren't shared with other dependency-injected types during each request. If you must share a scoped service between your middleware and other types, add these services to the Invoke method's signature.

In my example, the injected IAppLoggingRepository depends on IAppIdentity, which as a Transient per-request scope.