Dependency Injection with Ninject and Filter attribute for asp.net mvc

Question

I'm writing a custom Authorization Filter for asp.net mvc 3. I need to inject a userservice into the class but I have no idea how to do this.

public class AuthorizeAttribute : FilterAttribute, IAuthorizationFilter {     private IUserService userService;     private string[] roles;      public AuthorizeAttribute(params string[] roles)     {         this.roles = roles;     }      public void OnAuthorization(AuthorizationContext filterContext)     {         throw new NotImplementedException();     } } 

I'm using ninject for dependency injection. I do not want to use a Factory or service locator pattern.

My bindings look like this in the global.acsx:

    internal class SiteModule : NinjectModule     {         public override void Load()         {             Bind<IUserService>().To<UserService>();         }     } 

Answer 1

See this answer: Custom Authorization MVC 3 and Ninject IoC

If you want to use constructor injection then you need to create an attribute and a filter.

/// Marker attribute public class MyAuthorizeAttribute : FilterAttribute { }  /// Filter public class MyAuthorizeFilter : IAuthorizationFilter {       private readonly IUserService _userService;       public MyAuthorizeFilter(IUserService userService)       {           _userService = userService;       }        public void OnAuthorization(AuthorizationContext filterContext)       {           var validUser = _userService.CheckIsValid();            if (!validUser)           {               filterContext.Result = new RedirectToRouteResult(new RouteValueDictionary { { "action", "AccessDenied" }, { "controller", "Error" } });           }       } } 

Binding:

this.BindFilter<MyAuthorizeFilter>(System.Web.Mvc.FilterScope.Controller, 0).WhenControllerHas<MyAuthorizeAttribute>(); 

Controller:

[MyAuthorizeAttribute] public class YourController : Controller {     // ... } 

Answer 2

I would highly recommend B Z's answer. DO NOT use [Inject]!

I used an [Inject] like Darin Dimitrov said was possible and it actually caused threading issues under high load, high contention situations in conjunction with .InRequestScope.

B Z's way is also what is on the Wiki and I have seen many places where Remo Gloor (Ninject author) says this is the correct way to do it, e.g. https://github.com/ninject/ninject.web.mvc/wiki/Filter-configurations.

Downvote [Inject] answers in here because seriously you will get burned (probably in production if you don't load test properly beforehand!).