Is it possible to use async/await in MVC 4 AuthorizeAttribute?

Question

The only override I see exposed on MVC's AuthorizeAttribute is public override void OnAuthorization( AuthorizationContext filterContext ) which is not suitable for use with async/await because it doesn't return a Task. Is there another way to create an AuthorizeAttribute in MVC that allows the use of async/await?

Answer 1

ASP.NET MVC today does not support asynchronous filters. Please vote.

However, ASP.NET "vNext", announced at TechEd this week, will support asynchronous filters for MVC.

Answer 2

With asp.net core being released, Stephen Cleary's answer is correct and the ideal way to go if you are running the latest asp.net core.

For those that haven't updated yet, I was able to work around my issue using an async HttpModule that passes state into the AuthorizationFilter via HttpContext.Items. I added more detail about my solution here - http://evandontje.com/2017/08/15/solutions-for-async-await-in-mvc-action-filters/

Answer 3

For those who do not yet have the joy of being on .NET core, you can use this method from ASP.NET Web API 2 :

OnAuthorizationAsync override :

public override async Task OnAuthorizationAsync(HttpActionContext actionContext, CancellationToken cancellation)

for example, you can call an async webapi service like this :

 public override async Task OnAuthorizationAsync(HttpActionContext actionContext, CancellationToken cancellation)
    {
        await base.OnAuthorizationAsync(actionContext, cancellation);

        if (await IsUserAdminAsync()) /* call any async service */
            return;
        this.HandleUnauthorizedRequest(actionContext);
    }