Solve the Problems Related to automatic injection of Autofac MVC when Areas is split into different dll versions.

Due to the complexity of the project business, multiple Areas are created and placed in different projects. The project uses IOC implemented by AutoFac.

Configure the code

1 public class MvcApplication: System. web. httpApplication 2 {3 protected void Application_Start () 4 {5 // dependency injection 6 var builder = new ContainerBuilder (); 7 builder. registerModule (new ConfigurationSettingsReader ("autofac"); 8 builder. registerControllers (Assembly. getExecutingAssembly (); 9 10 var container = builder. build (); 11 DependencyResolver. setResolver (new AutofacDependencyResolver (container); 12 13 AreaRegistration. registerAllAreas (); 14 WebApiConfig. register (GlobalConfiguration. configuration); 15 FilterConfig. registerGlobalFilters (GlobalFilters. filters); 16 RouteConfig. registerRoutes (RouteTable. routes); 17} 18}

Using constructor in Controllers for Injection

Namespace xxx. web. person. controllers {// <summary> // positioning module // </summary> public class LocationController: Controller {private ILocationService _ location; public LocationController (ILocationService location) {_ location = location ;}}}

Error message after startup:

[MissingMethodException: No constructor without parameters is defined for this object.] System. runtimeTypeHandle. createInstance (RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean & canBeCached, RuntimeMethodHandleInternal & ctor, Boolean & bNeedSecurityCheck) + 0 System. runtimeType. createInstanceSlow (Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache) + 98 System. runtimeType. createInstanceDefaultCtor (Boolean publicOnly, Boolean skipVisibilityChecks, Boolean skipCheckThis, Boolean fillCache) + 241 System. activator. createInstance (Type type, Boolean nonPublic) + 69 System. web. mvc. defaultControllerActivator. create (RequestContext requestContext, Type controllerType) + 67

[InvalidOperationException: An error occurred while trying to create a controller of the "xxx. Web. Person. Controllers. HomeController" type. Make sure that the controller has a public constructor without parameters.]

The error message shows that the RegisterControllers of AutoFac only injects Controllers of xxx. Web into the referenced Controller of xxx. web. Person. dll.
The solution is as follows:

Public class MvcApplication: System. web. httpApplication {protected void Application_Start () {// dependency injection var builder = new ContainerBuilder (); builder. registerModule (new ConfigurationSettingsReader ("autofac"); builder. registerControllers (Assembly. getExecutingAssembly (); // solves the Areas injection problem in different Dll var assemblies = new DirectoryInfo (HttpContext. current. server. mapPath ("~ /Bin /")). getFiles ("*. dll "). select (r => Assembly. loadFrom (r. fullName )). toArray (); builder. registerAssemblyTypes (assemblies ). where (r => r. baseType = typeof (Controller )). instancePerHttpRequest (); var container = builder. build (); DependencyResolver. setResolver (new AutofacDependencyResolver (container); AreaRegistration. registerAllAreas (); WebApiConfig. register (GlobalConfiguration. configuration); FilterConfig. registerGlobalFilters (GlobalFilters. filters); RouteConfig. registerRoutes (RouteTable. routes );}}

Recompile and run normally.