Is it possible to use Dependency Injection/IoC on an ASP.NET MVC FilterAttribute?

Question

I've got a simple custom FilterAttribute which I use decorate various ActionMethods.

eg.

[AcceptVerbs(HttpVerbs.Get)]
[MyCustomFilter]
public ActionResult Bar(...)
{ ... }

Now, I wish to add some logging to this CustomFilter Action .. so being a good boy, I'm using DI/IoC ... and as such wish to use this pattern for my custom FilterAttribute.

So if i have the following...

ILoggingService

and wish to add this my custom FilterAttribute .. i'm not sure how. Like, it's easy for me to do the following...

public class MyCustomFilterAttribute : FilterAttribute
{
    public MyCustomFilterAttribute(ILoggingService loggingService)
    { ... }
}

But the compiler errors saying the attribute which decorates my ActionMethod (listed above...) requires 1 arg .. so i'm just not sure what to do :(

Answer 1

I've got property injection working with Ninject and the Ninject.Web.MVC.

As long as you've got the controller factory from Ninject.Web.MVC, it's rather simple.

E.g.

public class EventExistsAttribute : FilterAttribute, IActionFilter
{
    [Inject]
    public IEventRepository EventRepo { private get; set; }

    public void OnActionExecuting(ActionExecutingContext filterContext)
    {
        //Do stuff
    }

    public void OnActionExecuted(ActionExecutedContext filterContext)
    {
        //Do something else if you so wish...
    }
}

It has the drawback of essentially having a 'hidden' dependency, so to say... but there ain't much you can do about that.

HTHs,
Charles

Answer 2

You need to write your own IActionInvoker and do property injection. Have a look at this post by Jimmy Bogard for ideas.

Answer 3

Yes it is possible to use dependency injection on a FilterAttribute. However it not possible to use constructor injection on a FilterAttribute. This is not a limitation of ASP.NET MVC, it is a common to all .Net code, as the values passed into an attributes constuctor are limited to simple types.

[MyFilter(ILogger logger)] // this will not compile
public ActionResult Index()
{
    return View();
}

So the common practice is to make the dependency a property of your filter, as in @Charlino's example. You can then use property injection. You can use Ninject to decorate the filter property as in @Charlino's example. Or as suggested by @mrydengren, you can do this in a custom subclass of ControllerActionInvoker.