Question

I am trying to use Async controller and am not able to figure out how would one validate the user input.

Following are the two async methods defined in my controller. Should I check for ModelState.IsValid in the SearchAsync method or SearchCompleted method. If SearchAsync then how will return the view result as its return type is void. If SearchCompleted then how will the method know about searchForm parameter.

[HttpPost]
[ValidateAntiForgeryToken]
public void SearchAsync(BusinessSearchForm searchForm)
{
    AsyncManager.OutstandingOperations.Increment();
    new Thread(() =>
    {
        var suggestions = _searchSvc.GetSuggestions(searchForm.BusinessName, searchForm.StreetAddress, searchForm.City, searchForm.PostalCode);
        AsyncManager.Parameters["suggestions"] = suggestions;                   
        AsyncManager.OutstandingOperations.Decrement();
    }).Start();
}

public ActionResult SearchCompleted(IEnumerable<BusinessSuggestionBase> suggestions)
{
    return View(suggestions);
}

Answer 1

The following seems to work for me. I end up checking for modelstate in both methods. Added the initial model as a param to the completed method. Asp.net Mvc seemed to persist the modelstate between the two methods

    [HttpPost]
    [ValidateAntiForgeryToken]
    public void SearchAsync(BusinessSearchForm searchForm)
    {
        if (ModelState.IsValid)
        {
            AsyncManager.OutstandingOperations.Increment();
            new Thread(() =>
            {
                if (ModelState.IsValid)
                {
                    var suggestions = _searchBusinessSvc.GetSuggestions(searchForm.BusinessName, searchForm.StreetAddress, searchForm.City, searchForm.PostalCode);
                    AsyncManager.Parameters["suggestions"] = suggestions;
                }
                AsyncManager.Parameters["searchForm"] = searchForm;
                AsyncManager.OutstandingOperations.Decrement();
            }).Start();             
        }
    }

    public ActionResult SearchCompleted(BusinessSearchForm searchForm,IEnumerable<BusinessSuggestionBase> suggestions)
    {
        if (ModelState.IsValid)
        {
            TempData["suggestions"] = suggestions;
            return RedirectToAction("SearchResult");
        }
        return View(searchForm);
    }