Difference Between ViewResult() and ActionResult()

What is the difference between ViewResult() and ActionResult() in ASP.NET MVC?

public ViewResult Index()
{
    return View();
}

public ActionResult Index()
{
  开发者_StackOverflow中文版  return View();
}

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ActionResult is an abstract class that can have several subtypes.

ActionResult Subtypes

• ViewResult - Renders a specifed view to the response stream

• PartialViewResult - Renders a specifed partial view to the response stream

• EmptyResult - An empty response is returned

• RedirectResult - Performs an HTTP redirection to a specifed URL

• RedirectToRouteResult - Performs an HTTP redirection to a URL that is determined by the routing engine, based on given route data

• JsonResult - Serializes a given ViewData object to JSON format

• JavaScriptResult - Returns a piece of JavaScript code that can be executed on the client

• ContentResult - Writes content to the response stream without requiring a view

• FileContentResult - Returns a file to the client

• FileStreamResult - Returns a file to the client, which is provided by a Stream

• FilePathResult - Returns a file to the client

Resources

• What's the difference between ActionResult and ViewResult for action method? [ASP.NET Forums]

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ActionResult is an abstract class.

ViewResult derives from ActionResult. Other derived classes include JsonResult and PartialViewResult.

You declare it this way so you can take advantage of polymorphism and return different types in the same method.

e.g:

public ActionResult Foo()
{
   if (someCondition)
     return View(); // returns ViewResult
   else
     return Json(); // returns JsonResult
}

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It's for the same reason you don't write every method of every class to return "object". You should be as specific as you can. This is especially valuable if you're planning to write unit tests. No more testing return types and/or casting the result.

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ViewResult is a subclass of ActionResult. The View method returns a ViewResult. So really these two code snippets do the exact same thing. The only difference is that with the ActionResult one, your controller isn't promising to return a view - you could change the method body to conditionally return a RedirectResult or something else without changing the method definition.

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While other answers have noted the differences correctly, note that if you are in fact returning a ViewResult only it is better to return the more specific type rather than the base ActionResult type. An obvious exception to this principle is when your method returns multiple types deriving from ActionResult.

For a full discussion of the reasons behind this principle please see the related discussion here: Must ASP.NET MVC Controller Methods Return ActionResult?

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In the Controller , one could use the below syntax

public ViewResult EditEmployee() {
    return View();
}

public ActionResult EditEmployee() {
    return View();
}

In the above example , only the return type varies . one returns ViewResult whereas the other one returns ActionResult.

ActionResult is an abstract class . It can accept:

ViewResult , PartialViewResult, EmptyResult , RedirectResult , RedirectToRouteResult , JsonResult , JavaScriptResult , ContentResult, FileContentResult , FileStreamResult , FilePathResult etc.

The ViewResult is a subclass of ActionResult.

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In Controller i have specified the below code with ActionResult which is a base class that can have 11 subtypes in MVC like: ViewResult, PartialViewResult, EmptyResult, RedirectResult, RedirectToRouteResult, JsonResult, JavaScriptResult, ContentResult, FileContentResult, FileStreamResult, FilePathResult.

    public ActionResult Index()
                {
                    if (HttpContext.Session["LoggedInUser"] == null)
                    {
                        return RedirectToAction("Login", "Home");
                    }

                    else
                    {
                        return View(); // returns ViewResult
                    }

                }
//More Examples

    [HttpPost]
    public ActionResult Index(string Name)
    {
     ViewBag.Message = "Hello";
     return Redirect("Account/Login"); //returns RedirectResult
    }

    [HttpPost]
    public ActionResult Index(string Name)
    {
    return RedirectToRoute("RouteName"); // returns RedirectToRouteResult
    }

Likewise we can return all these 11 subtypes by using ActionResult() without specifying every subtype method explicitly. ActionResult is the best thing if you are returning different types of views.

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To save you some time here is the answer from a link in a previous answer at https://forums.asp.net/t/1448398.aspx

ActionResult is an abstract class, and it's base class for ViewResult class.

In MVC framework, it uses ActionResult class to reference the object your action method returns. And invokes ExecuteResult method on it.

And ViewResult is an implementation for this abstract class. It will try to find a view page (usually aspx page) in some predefined paths(/views/controllername/, /views/shared/, etc) by the given view name.

It's usually a good practice to have your method return a more specific class. So if you are sure that your action method will return some view page, you can use ViewResult. But if your action method may have different behavior, like either render a view or perform a redirection. You can use the more general base class ActionResult as the return type.