await not completing in extension method but working in controller - asp.net

Question

I am using async and await in a controller.
The following code works fine
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<ActionResult> Create(CompetitionViewModel viewModel)
{
if (ModelState.IsValid)
{
User user = null;
using (var facebookClient = new FacebookClient(viewModel.AccessToken))
{
var facebookUser = await facebookClient.Me();
user = entityStorage.GetUser(facebookUser);
FormsAuthentication.SetAuthCookie(user.FacebookId, true);
}
However if I try and execute the same code in an extension method then the await never completes.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(CompetitionViewModel viewModel)
{
if (ModelState.IsValid)
{
var user = entityStorage.GetCurrentUser(viewModel.AccessToken).Result;
and
public static class Helpers
{
public async static Task<User> GetCurrentUser(this IEntityStorage entityStorage, string accessToken)
{
User user = null;
using (var facebookClient = new FacebookClient(accessToken))
{
var facebookUser = await facebookClient.Me(); //STUCK HERE!!
user = entityStorage.GetUser(facebookUser);
FormsAuthentication.SetAuthCookie(user.FacebookId, true);
}
return user;
}
I am using MVC4 and have <add key="aspnet:UseTaskFriendlySynchronizationContext" value="true" /> set in my web.config as per other threads suggestions.
Can anyone tell me why this is and how I can get it to work?

Answer 1

I have a blog post that covers this in detail.
In short, you are causing a deadlock by calling Result. Instead, make your Create method async and use await to get the user.:
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<ActionResult> Create(CompetitionViewModel viewModel)
{
if (ModelState.IsValid)
{
var user = await entityStorage.GetCurrentUser(viewModel.AccessToken);