ASP.NET WebApi + Autofac not finding ApiControllers

Question

I'm trying to get Autofac to work with WebApi. I have my ApiControllers in a separate project from the main web project.

InventorySystem.Web.UI InventorySystem.Web.Api.Controllers

Whenever i try to browse to an api route i get the response:

<Exception xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <ExceptionType>System.ArgumentNullException</ExceptionType>
    <Message>Value cannot be null. Parameter name: value</Message>
    <StackTrace>
at System.Web.Http.Controllers.HttpControllerContext.set_Controller(IHttpController value)
at System.Web.Http.Dispatcher.DefaultHttpControllerFactory.CreateInstance(HttpControllerContext controllerContext, HttpControllerDescriptor controllerDescriptor)
at System.Web.Http.Dispatcher.DefaultHttpControllerFactory.CreateController(HttpControllerContext controllerContext, String controllerName)
at Autofac.Integration.WebApi.AutofacControllerFactory.CreateController(HttpControllerContext controllerContext, String controllerName)
at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsyncInternal(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    </StackTrace>
</Exception>

When i step through the Autofac code I see that my controller has been registered, but the AutofacControllerActivator.Create() returns null. Specifically the line return (ResolutionExtensions.ResolveOptional(scope, controllerType) as IHttpController);

The autofac code: string binDirectory = Path.Combine(HttpRuntime.AppDomainAppPath, "bin");

        var builder = new ContainerBuilder();

        builder.ConfigureWebApi(GlobalConfiguration.Configuration);

        builder.RegisterControllers(Assembly.GetExecutingAssembly()).PropertiesAutowired();
        builder.RegisterApiControllers(Assembly.LoadFile(Path.Combine(binDirectory, "InventorySystem.Web.Api.dll"))).PropertiesAutowired();
        builder.RegisterFilterProvider();            

        var container = builder.Build();

        DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
        GlobalConfiguration.Configuration.ServiceResolver.SetResolver(new AutofacWebApiDependencyResolver(container));

Am i missing something?

Thanks

Is the assembly location you are providing to RegisterAPIControllers definitely correct? I got the same error when I made a mistake with my assembly name. — Gavin
– Gavin, Commented Apr 29, 2012 at 13:27
@Gavin yes, because my apicontroller does get registerred. It's just the resolving which seems to fail. — user695595
– user695595, Commented Apr 29, 2012 at 14:45

Alex Meyer-Gleaves · Accepted Answer · 2012-05-03 13:27:39Z

2

The RegisterApiControllers registration extension looks for types that implement the IHttpController interface and have a name that ends with "Controller". Do your controller class names have a suffix of "Controller"?

answered May 3, 2012 at 13:27

Alex Meyer-Gleaves

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3 Comments

user695595 Over a year ago

Yes, it implements IHttpController eventually and the name also ends with Controller. Also, if i put my api controller in the main project it works fine. I'll try to create a test project to demonstrate the problem.

user695595 Over a year ago

I'm also not sure if lifetimeScope.ResolveOptional(controllerType) returns null or the cast to IHttpController. Any way I could check this easily?

Dennis Smit Over a year ago

(we work at the same place, thus I have access to the code): builder.RegisterApiControllers(typeof(InventorySystem.Web.Api.Controllers.InventoryController).Assembly).PropertiesAutowired(); fixed the issue, however we would like to be able to use Assembly.Load so we can switch between implementations and what not. Please advice why we see this behavior. (And: Thanks for the Autofac integration module! We love Autofac and all that integrates well with it)

Community · Accepted Answer · 2017-05-23 12:25:26Z

2

You might want to give a look at this SO question, where the other assembly is picked up starting from one of the references API Controllers.

edited May 23, 2017 at 12:25

CommunityBot

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answered Mar 6, 2013 at 11:13

superjos

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Comments

Jeremy Bell · Accepted Answer · 2012-05-03 00:28:02Z

0

Are you forgetting to register constructor dependencies for your Api controllers with the build container?

HostingEnvironment.MapPath("~/bin") is another good way to get the path to a file in the bin directory.

answered May 3, 2012 at 0:28

Jeremy Bell

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1 Comment

user695595 Over a year ago

Unfortunately that did not help.

Dharmesh Kumar Laxkar · Accepted Answer · 2016-06-07 09:34:53Z

-1

var builder = new ContainerBuilder();   
builder.Update(container);
 var webApiResolver = new Autofac.Integration.WebApi.AutofacWebApiDependencyResolver(container);
    System.Web.Http.GlobalConfiguration.Configuration.DependencyResolver = webApiResolver;

answered Jun 7, 2016 at 9:34

Dharmesh Kumar Laxkar

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