EF 6 + MVC Controller Actions

A controller action is a method on a controller that gets called when you enter a particular URL in your browser address bar. For example, you make a request for the following URL.

http://localhost:58379/Author/Edit/3

In this case, the Edit() action method is called on the AuthorController.

public ActionResult Edit(int? id)
{
    if (id == null)
    {
        return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
    }
    Author author = db.Authors.Find(id);
    if (author == null)
    {
        return HttpNotFound();
    }
    return View(author);
}

• A controller action must be a public method of a controller class.
• When you add a public method to a controller class is exposed as a controller action automatically.
• A method used as a controller action cannot be overloaded.
• Controller action cannot be a static method.
• You can use just about any method as a controller action.

Action Results

A controller action returns an action result in response to a browser request. The ASP.NET MVC framework supports several types of action results including:

• ViewResult: Represents HTML and markup.
• EmptyResult: Represents no result.
• RedirectResult: Represents a redirection to a new URL.
• JsonResult: Represents a JavaScript Object Notation result that can be used in an AJAX application.
• JavaScriptResult: Represents a JavaScript script.
• ContentResult: Represents a text result.
• FileContentResult: Represents a downloadable file (with the binary content).
• FilePathResult: Represents a downloadable file (with a path).
• FileStreamResult: Represents a downloadable file (with a file stream).

All of these action results inherit from the base ActionResult class, and mostly a controller action returns a ViewResult.

Controller Base Class

Normally, you do not return an action result directly, instead, you can call one of the following methods of the Controller base class:

• View: Returns a ViewResult action result.
• Redirect: Returns a RedirectResult action result.
• RedirectToAction: Returns a RedirectToRouteResult action result.
• RedirectToRoute: Returns a RedirectToRouteResult action result.
• Json: Returns a JsonResult action result.
• JavaScriptResult: Returns a JavaScriptResult.
• Content: Returns a ContentResult action result.
• File: Returns a FileContentResult, FilePathResult, or FileStreamResult depending on the parameters passed to the method.

For example, the Index() action in AuthorController does not return a ViewResult(). Instead, the View() method of the Controller base class is called.

public ActionResult Index()
{
    return View(db.Authors.ToList());
}

So, if you want to return a View to the browser, you call the View() method. If you want to redirect the user from one controller action to another, you call the RedirectToAction() method.

public ActionResult Create([Bind(Include = "AuthorId,FirstName,LastName,BirthDate")] Author author)
{
    try
    {
        if (ModelState.IsValid)
        {
            db.Authors.Add(author);
            db.SaveChanges();
            return RedirectToAction("Index");
        }
    }
    catch (DataException)
    {
        ModelState.AddModelError("", "Unable to save changes. Try again, and if the problem persists see your system administrator.");
    }
    return View(author);
}

The Create action in AuthorController either redirects the user to the Index() action or displays a view depending on whether the model state is valid.