As you cannot run async methods from child window (@Html.Action) calls, I have been searching for the simplest way to run async tasks from a non-async method. This will allow my MainMenu controller Menu action to still work when injected like this (rather than have to move to a VM or Ajax solution):
<div class="row">
@Html.Action("MainMenu", "Menu")
</div>
I tried this promising approach using a copy of the code MS use themselves: How to call asynchronous method from synchronous method in C#?
AsyncHelper code:
public static class AsyncHelper
{
private static readonly TaskFactory _myTaskFactory = new
TaskFactory(CancellationToken.None,
TaskCreationOptions.None,
TaskContinuationOptions.None,
TaskScheduler.Default);
public static TResult RunSync<TResult>(Func<Task<TResult>> func)
{
return AsyncHelper._myTaskFactory
.StartNew<Task<TResult>>(func)
.Unwrap<TResult>()
.GetAwaiter()
.GetResult();
}
public static void RunSync(Func<Task> func)
{
AsyncHelper._myTaskFactory
.StartNew<Task>(func)
.Unwrap()
.GetAwaiter()
.GetResult();
}
}
and I am consuming it like this:
public async Task<ActionResult> MainMenu()
{
if (_currentCandidate == null)
{
throw new ArgumentNullException("_currentCandidate");
}
var candidateId = AsyncHelper.RunSync<int>(() => _currentCandidate.CandidateIdAsync());
[snip]
}
Which calls this async method:
public async Task<int> CandidateIdAsync()
{
var applicationUser = await this.ApplicationUserAsync();
if (applicationUser != null)
{
return applicationUser.CandidateId.GetValueOrDefault();
}
return 0;
}
Only when I run this I get the following error:
What am I missing here? The code looks like it should work, but I am not familiar enough with it yet to figure it out.
Update:
For reference the MainMenu controller class looks like this:
public class MenuController : Controller
{
readonly ICurrentCandidate _currentCandidate;
public MenuController(ICurrentCandidate currentCandidate)
{
_currentCandidate = currentCandidate;
}
// GET: MainMenu
public ActionResult MainMenu()
{
if (_currentCandidate == null)
{
throw new ArgumentNullException("_currentCandidate");
}
var candidateId = AsyncHelper.RunSync<int>(() => _currentCandidate.CandidateIdAsync());
[snip]
return View(vm);
}
}
Another update:
The failure appears to be inside the related IF code as a simplified CandidateIdAsnyc works:
// This works
public async Task<int> CandidateIdAsync()
{
return 0;
}
Here is the rest of that code:
public class CurrentCandidate : ICurrentCandidate
{
private readonly ApplicationDbContext _applicationDbContext;
private readonly IApplicationUserManager _userManager;
private readonly ICandidateStore _candidateStore;
public CurrentCandidate(ApplicationDbContext applicationDbContext, ICandidateStore candidateStore, IApplicationUserManager userManager)
{
this._candidateStore = candidateStore;
this._applicationDbContext = applicationDbContext;
this._userManager = userManager; // new ApplicationUserManager(new UserStore<ApplicationUser>(this._applicationDbContext));
}
public async Task<ApplicationUser> ApplicationUserAsync()
{
var applicationUser = await this._userManager.FindByIdAsync(HttpContext.Current.User.Identity.GetUserId());
return applicationUser;
}
public bool IsAuthenticated()
{
return HttpContext.Current.User.Identity.IsAuthenticated;
}
public async Task<int> CandidateIdAsync()
{
var applicationUser = await this.ApplicationUserAsync();
if (applicationUser != null)
{
return applicationUser.CandidateId.GetValueOrDefault();
}
return 0;
}
}
