确保控制器在Web API中具有无参数的公共构造函数?

本文介绍了确保控制器在Web API中具有无参数的公共构造函数?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在努力解决使用 uniy 进行依赖项注入的问题.我已根据此链接实现 www.asp/web-api/overview/advanced/dependency-injection

I am struggling with this problem of dependency injection using untiy. I have implemented according to this link www.asp/web-api/overview/advanced/dependency-injection

但是出现了这个错误:

{ "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)" } }

我的Web Api控制器:

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 } ); } }

无法确定问题出在哪里?能否请您进入代码并让我知道. 我关注了以下所有这些链接

Unable to identify where the problem is? Can please get into the code and let me know. I have followed all these below links

确保控制器具有无参数的public构造函数?

Autofac-确保控制器有一个无参数的公共构造函数

确保控制器有一个使用Ninject的无参数公共构造函数

请确保控制器具有无参数的公共构造函数错误

但是这些都不能解决我的问题.

But none of these solved my problem.

推荐答案

当我在一个项目中同时使用MVC和WebAPI时，通过使用此链接，我需要解决这两个依赖关系.

As i am using both MVC and WebAPI in one project, i understood by using this link that i need to resolve both dependencies.

因此，我删除了WebAPIConfig.cs文件中的以下代码

So, i removed below code in WebAPIConfig.cs file

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

在我的项目中安装了一个名为 Unity.WebAPI 的软件包之后.

After i installed one package called Unity.WebAPI in my project.

在UnityConfig.cs文件中添加了以下代码

Added below code in UnityConfig.cs file

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

就是这样，解决了我的问题！

That's it, solved my problem!