controllers & actions

Controllers & Actions in MVC

Eyal VardiCEO E4D Solutions LTDMicrosoft MVP Visual C#blog: www.eVardi.com

© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: [email protected]

Agenda

Controllers Overview

ViewData vs. ViewBag

Action & ActionResult

Controller Attributes

Async Controller


Understanding Controllers

MVC controllers are responsible for responding to requests made against an ASP.NET MVC website.


The Controller Responsibility

Execute the right action method and validating that it can be called.

Getting the values to use as the action method's arguments.

Handling all errors that might occur during the execution of the action method.

Providing the default WebFormViewEngine class for rendering ASP.NET page types (views).


Controller Sample

http://E4D.co.il / Course / Net / MVC / http://E4D.co.il / Course/ Net ? name=MVC

public class CourseController : Controller{ public ActionResult Net( string name ) { var course = BL.GetCourse(name); return View( course ); }}


ViewData Property

Used to set view-specific data in a dictionary object that can hold multiple name/value pairs.

public class CourseController : Controller{ public ActionResult Net( string name ) { ViewData["Course"] = BL.GetCourse(name); return View(); }}


ViewBag Property

Used to set view-specific data in a dictionary object that can hold multiple name/value pairs.

public class CourseController : Controller{ public ActionResult Net( string name ) { ViewBag.Course = BL.GetCourse(name); return View(); }}


Actions Action == Method

Action must meet certain requirements:

Must be public.

Cannot be a static method.

Cannot be an extension method.

Cannot have open generic types.

The method is not a method of the controller base class.

The method cannot contain ref or out parameters.


Preventing an Action to Invoke

Prevent the method from being invoked by using the [NonAction] attribute.

public class HomeController : Controller{ [NonAction] public string CompanySecrets() { return "This information is secret."; } ...}


Action Results

A controller action returns something called an action result.

Action results types:

ViewResult

EmptyResult

RedirectResult

JsonResult

JavaScriptResult

ContentResult

FileContentResult

FilePathResult

FileStreamResult

HttpNotFoundResult

HttpRedirectResult

HttpStatusCodeResult


Controller “View” Methods

Normally, you do not

return an action result

directly. Instead, you call

one of the following

methods of the

Controller base class.


Controller “View”Methods


Controller Class


Controller Attributes

[ActionName]

[NonAction]

[AcceptVerbs] [HttpGet]

[HttpPost]

[HttpPut]

[HttpDelete]

[ChildActionOnly

]

[SessionState]

[OutputCache]


SessionState Attribute

Using the attribute, you can completely turn on or off session state, adjust it to read-only, or make it required. Default, Required, ReadOnly & Disabled.

[SessionState( SessionStateBehavior.Disabled )]public class HomeController : Controller { public ActionResult Index() { Session["E4D"] = "E4D Learning"; return View(); } }


OutputCache Attribute[ChildActionOnly][OutputCache( Duration = 20 )]public ActionResult CurrentTime() { return PartialView(); }

<h2>OutputCache Sample</h2> View Time: @DateTime.Now.ToString("h:mm:ss")<br /> Partial View Time: @{ Html.RenderAction("CurrentTime"); }


Async Controller

The AsyncController class enables you to write asynchronous action methods.


Async Action

public class PortalController : AsyncController{ [AsyncTimeout(Duration = 5000 )] public void NewsAsync(string city) { AsyncManager.OutstandingOperations.Increment(); NewsService newsService = new NewsService(); newsService.GetHeadlinesCompleted += (sender, e) => { AsyncManager.Parameters["headlines"] = e.Value; AsyncManager.OutstandingOperations.Decrement(); }; newsService.GetHeadlinesAsync(city); } public ActionResult NewsCompleted(NewsHeadline[] headlines) { return View( "News", new ViewStringModel { Headlines = headlines } ); }}

Async Action


Async Action

controllers & actions

Technology

controller class

controller samplehttp

controller viewmethods

right action method

controller base class

action results types

asynchronous action

action methods arguments