Async call in MVC 4

Question

Working on MVC 4 application. I need to do certain DB calls with out blocking the current action method execution.

public ActionResult Save(Employee e){

  bool saveStatus = EmployeeService.Save(e);

  if(saveStatus){
   AuditService.Add("Employee {0} added successfully", e.Name); //want this async
  }
  return View(e);

}

In the above code I want to make the AuditService call to async.

The moment I save employee information i need to return the view instead of waiting for AuditService call.

I am new to async and await in MVC 4.

Answer 1

I think using Task is a better approach here:

if(saveStatus){
    new Task(AuditService.Add("Employee {0} added successfully", e.Name)).Start();
}  

Update:
As Stephen pointed out in his answer, this may cause your in-progress work to be lost.

Answer 2

You do it wrong. You can't run async inside any action of a simple controller. Because your client's code runs when server's code is completed and it isn't have the sense.

Depend on your target, you can do next:

• If you want to reduce the number of active connections, you have to use ASP.NET MVC asynchronous Controllers (AsyncController). Check details by the next links: Using Asynchronous Methods in ASP.NET MVC 4, Using Asynchronous Controllers, Using an Asynchronous Controller in ASP.NET MVC. There described different ways to do it. Frankly, I haven't check every of these methods, so I share all.
• If you want to load some visual elements immediately and after this make call to your DB data, you have to move DB code under Ajax calls. Check details by the next links: MVC JSON - JsonResult and jQuery, Json Method, Using JsonResult with jquery in ASP.net MVC(with example). But I recommend you try asp.net mvc web api - ASP.NET WEB API Basics (MVC 4), Your First ASP.NET Web API.

Answer 3

As I describe on my blog, async does not change the HTTP protocol. What you're asking for is how to return early from an HTTP request; this doesn't have anything to do with async/await.

Regarding returning early from HTTP requests: You almost never want to do this.

If your "audit" service is actually a log - and you are perfectly fine with the occasional log message not being logged - then (and only then) you can use an approach like I describe on my blog.

Otherwise, you shouldn't return early. I.e., if your "audit" service is actually used for auditing, or if you expect your log to be accurate. In this case, you cannot return early.