`AddHttpMessageHandler` that contains constructor dependency/reference of typed `HttpClient` solved at `AddHttpClient` method

Question

I'm trying to add AddHttpMessageHandler that uses a service resolved by AddHttpClient, but when execution call the referenced MessageHandler he throws an exception:

ValueFactory attempted to access the Value property of this instance

System.InvalidOperationException: ValueFactory attempted to access the Value property of this instance.
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.get_Value()
   at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateHandler(String name)
   at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateClient(String name)
   at Microsoft.Extensions.DependencyInjection.HttpClientBuilderExtensions.<>c__DisplayClass12_0`2.<AddTypedClientCore>b__0(IServiceProvider s)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(FactoryCallSite factoryCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitDisposeCache(ServiceCallSite transientCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitDisposeCache(ServiceCallSite transientCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass1_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.HttpClientBuilderExtensions.<>c__4`1.<AddHttpMessageHandler>b__4_1(HttpMessageHandlerBuilder b)
   at Microsoft.Extensions.Http.DefaultHttpClientFactory.<>c__DisplayClass17_0.<CreateHandlerEntry>g__Configure|0(HttpMessageHandlerBuilder b)
   at Microsoft.Extensions.Http.LoggingHttpMessageHandlerBuilderFilter.<>c__DisplayClass3_0.<Configure>b__0(HttpMessageHandlerBuilder builder)
   at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateHandlerEntry(String name)
   at Microsoft.Extensions.Http.DefaultHttpClientFactory.<>c__DisplayClass14_0.<.ctor>b__1()
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.get_Value()
   at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateHandler(String name)
   at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateClient(String name)
   at Microsoft.Extensions.DependencyInjection.HttpClientBuilderExtensions.<>c__DisplayClass12_0`2.<AddTypedClientCore>b__0(IServiceProvider s)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(FactoryCallSite factoryCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitDisposeCache(ServiceCallSite transientCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass1_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired)
   at lambda_method9(Closure , IServiceProvider , Object[] )
   at Microsoft.AspNetCore.Mvc.Controllers.ControllerActivatorProvider.<>c__DisplayClass4_0.<CreateActivator>b__0(ControllerContext controllerContext)
   at Microsoft.AspNetCore.Mvc.Controllers.ControllerFactoryProvider.<>c__DisplayClass5_0.<CreateControllerFactory>g__CreateController|0(ControllerContext controllerContext)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()

Full code:

public class AuthHeaderHandler : DelegatingHandler
{
    private readonly IMyApi _myApi;

    public AuthHeaderHandler(IMyApi myApi)
    {
        _myApi = myApi;
    }

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var accessToken = await _myApi.GetAccessToken();

        request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);

        return await base.SendAsync(request, cancellationToken).ConfigureAwait(false);
    }
}

---

public interface IMyApi
{
    Task<int[]> GetSomeInfo1();
    Task<int[]> GetSomeInfo2();
    Task<string> GetAccessToken();
}

public class MyApi : IMyApi
{
    public MyApi(HttpClient myApiHttpClient)
    {
         // omitted for brevity...
    }

    public Task<string> GetAccessToken()
    {
        // omitted for brevity...
    }

    public Task<int[]> GetSomeInfo1()
    {
        // omitted for brevity...
    }

    public Task<int[]> GetSomeInfo2()
    {
        // omitted for brevity...
    }
}

---

D.I

services
    .AddHttpClient<IMyApi, MyApi>
    (
        configureClient =>
        {
            configureClient.BaseAddress = new Uri("https://myapi.com/");
        }
    )
    .AddHttpMessageHandler<AuthHeaderHandler>();

services.AddTransient<AuthHeaderHandler>();

Well, only to be more "visual":

---

The idea of DelegatingHandler is to add authorization header on all requests made by that HttpClient (AddHttpClient<IMyApi, MyApi>).

The interface IMyApi implements/represents all methods of an Api (Auth & Others) and in this case, AuthHeaderHandler class depends/uses IMyApi at ctor to call GetAccessToken() resolved by .AddHttpClient<IMyApi, MyApi>() method.

Is .AddHttpClient() "lazy load" and only run this configuration at first http request? Why we can't: "Only AddHttpMessageHandler after resolve D.I of AddHttpClient to avoid this exception"?

Something similar here.

Any idea?

Answer 1

Add registration for Lazy<IMyApi> or Func<IMyApi> to DI container and inject it to the AuthHeaderHandler ctor. The problem is cycle dependencies: HttpClient injects MyApi(implicitly via Handler) and MyApi injects HttpClient.