Make sure the controller has a hassle-free public constructor in the web api?

Question

I am struggling with this problem of dependency injection using untiy . I implemented this link https://www.asp.net/web-api/overview/advanced/dependency-injection

But this error turned out:

{ "Message": "An error has occurred.", "ExceptionMessage": "An error occurred when trying to create a controller of type 'WebAPIController'. Make sure that the controller has a parameterless public constructor.", "ExceptionType": "System.InvalidOperationException", "StackTrace": " at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)\r\n at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request)\r\n at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()", "InnerException": { "Message": "An error has occurred.", "ExceptionMessage": "Type 'Fairmoves.Controllers.WebAPIController' does not have a default constructor", "ExceptionType": "System.ArgumentException", "StackTrace": " at System.Linq.Expressions.Expression.New(Type type)\r\n at System.Web.Http.Internal.TypeActivator.Create[TBase](Type instanceType)\r\n at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator)\r\n at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)" } } 

My Web Api Controller:

 [RoutePrefix("api/WebAPI")] public class WebAPIController : ApiController { private readonly IUserBusinessService UserBusinessService; private readonly ILoginBusinessService LoginBusinessService; //public WebAPIController():base() //{ //} public WebAPIController(IUserBusinessService UserBusinessService, ILoginBusinessService LoginBusinessService) { this.UserBusinessService = UserBusinessService; this.LoginBusinessService = LoginBusinessService; } [HttpPost] public IHttpActionResult Login([FromBody]AuthModels.LoginModel model) { // string strUserId = credentials.LoginName; //string strPassword = credentials.Password; var serviceResultDAO1 = LoginBusinessService.LoginUserSubmit(model.LoginName); } } 

UnityResolver.cs

 public class UnityResolver:IDependencyResolver { protected IUnityContainer container; public UnityResolver(IUnityContainer container) { if (container == null) { throw new ArgumentNullException("container"); } this.container = container; } [DebuggerStepThrough] public object GetService(Type serviceType) { try { return container.Resolve(serviceType); } catch (ResolutionFailedException) { return null; } } [DebuggerStepThrough] public IEnumerable<object> GetServices(Type serviceType) { try { return container.ResolveAll(serviceType); } catch (ResolutionFailedException) { return new List<object>(); } } public IDependencyScope BeginScope() { var child = container.CreateChildContainer(); return new UnityResolver(child); } public void Dispose() { container.Dispose(); } } 

}

WebApiConfig.cs

 public static class WebApiConfig { public static void Register(HttpConfiguration config) { //config.DependencyResolver = new NinjectResolver(); var container = new UnityContainer(); container.RegisterType<ILoginBusinessService, LoginBusinessService>(new HierarchicalLifetimeManager()); container.RegisterType<IUserBusinessService, UserBusinessService>(new HierarchicalLifetimeManager()); config.DependencyResolver = new UnityResolver(container); //DependencyResolver.SetResolver(new UnityDependencyResolver(container)); config.MapHttpAttributeRoutes(); config.Routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{action}/{id}", defaults: new { id = RouteParameter.Optional } ); } } 

Unable to determine where the problem is? Please, enter the code and inform me. I followed all of these links below

Make sure that the controller does not have a constructor without parameters?

Autofac - make sure the controller does not have a constructor without parameters

Make sure the controller does not have a constructor without parameters without using Ninject

Make sure the controller has an error without a constructor

But not one of them solved my problem.

Answer 1

Since I use both MVC and WebAPI in one project, I realized using this one that I need to resolve both dependencies.

So, I deleted the code below in the WebAPIConfig.cs file

 var container = new UnityContainer(); container.RegisterType<ILoginBusinessService, LoginBusinessService>(new HierarchicalLifetimeManager()); container.RegisterType<IUserBusinessService, UserBusinessService>(new HierarchicalLifetimeManager()); config.DependencyResolver = new UnityResolver(container); 

After one package was installed in my project with the name Unity.WebAPI .

Added below code in UnityConfig.cs file

 GlobalConfiguration.Configuration.DependencyResolver = new Unity.WebApi.UnityDependencyResolver(container); 

That he solved my problem!