ASP.NET MVC Controllers & Actions

ControllersResponsible for controlling the flow of applicationExposes public methods as actionsEach action returns different results typesInherits from System.Web.Mvc.Controller

Returning Action ResultsViewResult View()PartialViewResult PartialView()RedirectResult Redirect()ContentResult Content()JsonResult Json()FileResult File()EmptyResult HttpUnauthorizedResultJavaScriptResult JavaScript()RedirectToRouteResult RedirectToRoute()

Returning View ResultsReturns HTML to the browserImplicit vs Explicit view namingreturn View();return View(‘’ViewName’’)Specifying pathsreturn View(‘’SubFolder/ViewName’’)return View(‘’~/View.aspx’’)

Returning Redirect ResultsSame controllerreturn RedirectToAction(‘’Index’’);Different controllerreturn RedirectToAction(‘’Product’’, ‘’List’’);Providing route valuesreturn RedirectToAction(‘’Product’’, ‘’Details’, new { id = 20 });

Returning Content Resultsreturn Content(‘’Hello’’);Returning .Net typespublic string HelloAction() {return ‘’Hello’’;}ToString() and wrapping with ContentResult

Returning Json ResultsReturns result in JavaScript Object Notation (JSON) formatUses JavaScriptSerializer{ id: 10, name: ‘SharePoint 2010’, authors: [{ ‘onsela’, ‘mehmeta’ }]}var books = new List<Book>();return Json(books);

Returning JavaScriptpublic ActionResult ShowMessage() {return JavaScript(‘’alert(‘Message!’);’’);}// View.aspx<%: Ajax.ActionLink(‘’Show message’’, ‘’ShowMessage’’, null) %>

Action Method Parameters – 1public ActionResult ShowInfo(string city) { // Equivalent tovar tempCity = Request.Form[‘’city’’];}Optional ParametersNullable typesDefaultValueAttributeOptional Parameters with C# 4.0Complex Parameterspublic ActionResult Update(Product p) { .... }

Action Method Parameters – 2Invoking model binding manuallypublic ActionResult Update(int productID) {var product = repository.Get(productID);UpdateModel(product);repository.Update(product);return View(product);}

Passing Data to Views – 1Controllers and views are totally independentControllers suply data to viewsNo way to access controllers from viewsSupplying data from a controllerViewData[‘’product’’] = productObject;Accessing data from the view<%: ((Product)ViewData[‘’product’’]).Name %>

Passing Data to Views – 2Sending strongly typed objects to viewspublic ActionResult ProductInfo(int id) {var product = repository.Get(id);return View(product);}// View.aspxProduct Name: <%: Model.Name %>

Passing Data to Views – 3Passing dynamic objects to viewspublic ActionResult ProductDetails(int id) {dynamic model = new ExpandoObject();model.Product = repository.Get(id);model.Message = ‘’Out of Stock’;return View(model);}// View.aspx<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<dynamic>" %>Product: <%: Model.Product.Name %>Message: <%: Model.Message %>

Using TempDataSimilar usage with ViewDataPreserves data across redirectionspublic ActionResult Update(Product product) {repository.Update(product);TempData[‘’message’’] = ‘’Product ‘’ + product.Name + ‘’ updated.’’;return RedirectToAction(‘’Success’’);}// Success action view.aspx<% if (TempData[‘’message’’] != null) %><p><%: TempData[‘’message’’] %></p><% } %>

Using FiltersInjects extra behaviors to controller and actionsDerive from FilterAttribute classBasic types of filters

Applying Filters[Authorize(Roles=‘’Administrator’’)]public class ProductController : Controller { [OutputCache(Duration=30)]public ActionResult Save(Product p) {}}

How Filters are Executedtry{Run each IAuthorizationFilter'sOnAuthorization() methodif(none of the IAuthorizationFilters cancelled execution) {Run each IActionFilter'sOnActionExecuting() method Run the action methodRun each IActionFilter'sOnActionExecuted() method (in reverse order)Run each IResultFilter'sOnResultExecuting() method Run the action resultRun each IResultFilter'sOnResultExecuted() method (in reverse order) } else {Run any action result set by the authorization filters }}catch(exception not handled by any action or result filter){Run each IExceptionFilter'sOnException() methodRun any action result set by the exception filters}

IActionFilter, IResultFilter Methods

Authorize FilterRun early in the requestUsers propertyRoles propertyOrder property[Authorize(Roles=‘’SalesRep’’, Users=‘’onsela’’)]public ActionResult ProductList() { return View();}

HandleError FilterDetects exceptionsRenders a specific viewReturns HTTP status code 500 to clients[HandleError(View=‘’ErrorPage’’, ExceptionType=typeof(SqlException)]public ActionResult ProductList() { return View();}

Handling Unknown Actionspublic class HomeController : Controller{ protected override void HandleUnknownAction(string actionName) { ..... }}

ASP.NET MVC Controllers & Actions

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