Asp.net mvc internals & extensibility

MVC Internals &Extensibility Eyal Vardi CEO E4D Solutions LTD Microsoft MVP Visual C# blog: www.eVardi.com

Routes  A route is a URL pattern that is mapped to a handler.  The handler can be a physical file, such as an .aspx file in a Web Forms application.  A handler can also be a class that processes the request, such as a controller in an MVC application. protected void Application_Start() Global.asax { RouteTable .Routes .MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL template new { controller="Calc", action="Add", id=UrlParameter.Optional } ); }© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

URL Patterns in MVC Applications  {Controller} / {Action} / {id}  Query / {queryname} / {*queryvalues}  “*” This is referred to as a catch-all parameter.  /query/select/bikes/onsale  queryname = "select" , queryvalues = "bikes/onsale"© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Adding Constraints to Routes  Constraints are defined by using regular expressions string or by using objects that implement the IRouteConstraint interface. protected void Application_Start() Global.asax { RouteTable .Routes .MapRoute( "Blog", "Posts/{postDate}", new { controller="Blog",action="GetPosts" } ); } /Posts/28-12-71 => BlogController,GetPosts( “28-12-1971” ) /Post/28 => BlogController,GetPosts( “28” ) /Post/test => BlogController,GetPosts( “test” )© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

IRouteConstraint protected void Application_Start() Global.asax { RouteTable .Routes .MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL template new { controller="Calc", action="Add", id=UrlParameter.Optional }, new { action = new MyRouteConstraint() } ); } Custom Route Constraint© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Regular Expression Route Constraint protected void Application_Start() { RouteTable .Routes .MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL template new { controller="Calc", action="Add", id=UrlParameter.Optional }, new { action = @"d{2}-d{2}-d{4}" } ); } Regular Expression© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Dependency Resolver  Service locator for the framework. protected void Application_Start() { ... DependencyResolver.SetResolver(new TraceDependencyResolver() ); }© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Understanding Controllers  MVC controllers are responsible for responding to requests made against an ASP.NET MVC website.© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Creation of the Controller  IControllerFactory Responsible for determining the controller to service the request.  IControllerActivator Responsible for creating the controller  DefaultControllerFactory has internal class called DefaultControllerActivator.© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Creation of the Controller Request Routing MvcRouteHandler MvcHandler Dependency Controller Dependency Controller Resolver Resolver Controller Factory Activator© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

The Action Execution Request Routing MvcRouteHandler MvcHandler Dependency Controller Dependency Controller Resolver Resolver Controller Factory Activator Action Action Invoker Method© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

The Action Execution  Once the controller has been instantiated, the specified action has to be executed, and this is handled by the IActionInvoker.  If you derived your controller from the Controller class, then this is the responsibility of an action invoker.© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Custom Action Name  You can then accept an action name that wouldn’t be legal as a C# method name.  [ActionName("User-Registration")]  [ActionNameSelector]© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Action Method Selection  The action invoker uses an action method selector to remove ambiguity when selecting an action.  The invoker gives preference to the actions that have selectors.© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Custom Action Method Selector  You return true from IsValidForRequest if the method is able to process a request, and false otherwise.© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

HTTP to .NET Classes public ActionResult Index(Reservation reservation) { // TODO BL. return View( reservation ); } Deserialization© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Model Binders  Binders are like type converters, because they can convert HTTP requests into objects that are passed to an action method.© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

DefaultModelBinder Class  Translate HTTP request into complex models, including nested types and arrays.  URL  Form data, Culture - Sensitive 1. Request.Form 2. RoutedData.Values (Key,Value) 3. Request.QueryString 4. Request.Files© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Model Binder Types  ByteArrayModelBinder  LinqBinaryModelBinder  FormCollectionModelBinder  HttpPostedFileBaseModelBinder  DefaultModelBinder© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Binding to Complex Types [DisplayName("Book")] Model public class E4DBook { [Display(Name = "Title")] public string E4DTitle { get; set; } public Reservation MyReservation { get; set; } } @Html.LabelFor(model => model.MyReservation.FlightNum) View @Html.EditorFor(model => model.MyReservation.FlightNum) Html <label for="MyReservation_FlightNum">FlightNum</label> <input type="text" value="" id = "MyReservation_FlightNum" name = "MyReservation.FlightNum" />© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Specifying Custom Prefixes Controller public ActionResult Index( Reservation res1 , [Bind(Prefix="myRes")] Reservation res2 ) { ... } <!– First Arg --> Html <label for="FlightNum">FlightNum</label> <input type="text" id="FlightNum" name="FlightNum" /> ... <!– Second Arg --> <label for="MyRes_FlightNum">FlightNum</label> <input type="text" id="MyRes_FlightNum" name="MyRes.FlightNum" />© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Bind Attribute (“View”)  Represents an attribute that is used to provide details about how model binding to a parameter should occur. [Bind(Include = "FlightNum, TravelDate)] public class Reservation { public int FlightNum { get; set; } public DateTime TravelDate { get; set; } public int TicketCount { get; set; } public int DiscountPercent { get; set; } }© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Binding to a String Collections Controller public ActionResult Index( List< string > reservation ) { ... } Html <input type="text" name="reservation" /> <input type="text" name="reservation" /> <input type="text" name="reservation" /> <input type="text" name="reservation" />© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Binding to a Collections Controller public ActionResult Index( List<Reservation> reservation ) { ... } <!– Option I--> Html <input type="text" name="[0].Name" /> <input type="text" name="[1].Name" /> <!– Option II --> <input type="hidden" name="Index" value="f1" /> <input type="text" name="[f1].Name" /> <input type="hidden" name="Index" value="f2" /> <input type="text" name="[f2].Name" />© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Binding to a Dictionary Controller public ActionResult Index( Dictionary<Reservation> reservation ) { ... } Html <input type="hidden" name="[0].key" value="f1" /> <input type="text" name="[0].value.Name" /> <input type="hidden" name="[1].key" value="f2" /> <input type="text" name="[1].value.Name" />© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Custom Model Binders  ASP.NET MVC allows us to override both the default model binder, as well as add custom model binders. ModelBinders.Binders.DefaultBinder = new CustomDefaultBinder(); ModelBinders.Binders.Add( typeof(DateTime), new DateTimeModelBinder() );© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

ModelBinder Attribute  Represents an attribute that is used to associate a model type to a model-builder type. public ActionResult Contact( [ModelBinder(typeof(ContactBinder))] Contact contact ) { ViewData["name"] = contact.Name; ViewData["email"] = contact.Email; ViewData["message"] = contact.Message; ViewData["title"] = "Succes!"; return View(); }© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Model Summary  Http to .NET Classes  IModelBinder  IValueProvider  ModelMetadataProvider  BindAttribute  Validation  Data Annotations  IValidateObject© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Action Results  A controller action returns something called an action result.  Action results types:  ViewResult  FileContentResult  EmptyResult  FilePathResult  RedirectResult  FileStreamResult  JsonResult  HttpNotFoundResult  JavaScriptResult  HttpRedirectResult  ContentResult  HttpStatusCodeResult© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

ASP.NET MVC Filters  Filters are custom classes that provide both a declarative and programmatic means to add pre-action and post-action behavior to controller action methods. [HandleError] [Authorize] public class CourseController : Controller { [OutputCache] [RequireHttps] public ActionResult Net( string name ) { ViewBag.Course = BL.GetCourse(name); return View(); } }© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Filter Order  Filters run in the following order:  Authorization filters  Action filters  Response filters  Exception filters© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Controller & Filters  The Controller class implements each of the filter interfaces.  You can implement any of the filters for a specific controller by overriding the controllers On<Filter> method.  OnAuthorization  OnActionExecuting  OnActionExecuted  OnResultExecuting  OnResultExecuted  OnException© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

IAuthorizationFilter  Make security decisions about whether to execute an action method.  AuthorizeAttribute  RequireHttpsAttribute© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

IActionFilter Interface  OnActionExecuting  Runs before the action method.  OnActionExecuted  Runs after the action method© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

IResultFilter Interface  OnResultExecuting  Runs before the ActionResult object is executed.  OnResultExecuted  Runs after the result.  Can perform additional processing of the result.  The OutputCacheAttribute is one example of a result filter.© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

IExceptionFilter  Execute if there is an unhandled exception thrown during the execution of the ASP.NET MVC pipeline.  Can be used for logging or displaying an error page.  HandleErrorAttribute is one example of an exception filter.© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Handle Error Attribute  You can specify an exception and the names of a view and layout.  Works only when custom errors are enabled in the Web.config file  <customErrors mode="On" /> inside the <system.web>  The view get HandleErrorInfo© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

First Global Controller Action Last Filter I Filter I Filter I Filter I Filter I Filter II Filter II Filter II Filter II Filter II Action Method Action Result Authorization Action Result Exception Filter I Filter I Filter I Filter I Filter I Filter II Filter I Filter II Filter I Filter II Filter I Filter I Filter I Filter I Filter I Filter II Filter I Filter II Filter I Filter I Filter I Filter I Filter II Filter II Filter I Filter I Filter I Filter I Filter II Filter I Filter I Filter II Filter I Filter II Filter I Filter I Filter I Filter I Filter I Filter I© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Action Before After Filter I Filter II Filter I Filter II Filter I Filter II Filter I Filter II Filter I Filter II Filter II Filter I Filter II Filter I Filter II Filter I Filter II Filter I Filter II Filter I© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Custom Filter  You can create a filter in the following ways:  Override one or more of the controllers On<Filter> methods.  Create an attribute class that derives from ActionFilterAttribute or FilterAttribute.  Register a filter with the filter provider (the FilterProviders class).  Register a global filter using the GlobalFilterCollection class.© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Filter Providers  By default, ASP.NET MVC registers the following filter providers:  Filters for global filters.  FilterAttributeFilterProvider for filter attributes.  ControllerInstanceFilterProvider for controller instances.  The GetFilters method returns all of the IFilterProvider instances in the service locator.© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

Filter Summary  Custom Filters  IAuthorizationFilter  IActionFilter  IResultFilter  IExceptionFilter  IFilterProvider© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

MVC Internals & Extensibility Summary Mvc Routing RouteHandler MvcHandler Dependency Controller Dependency Controller Resolver Resolver Controller Factory Activator Action Name Method Authorization Model Invoker Selector Selectror Filter Bind Action Action Action Result View Filer Method Filer Filter Engine Result Exception View Filter Filter© 2010 E4D LTD. All rights reserved. Tel: 054-5-767-300, Email: Eyal@E4D.co.il

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Asp.net mvc internals & extensibility

by Eyal Vardi on Oct 10, 2011

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