Asp.net mvc internals & extensibility

MVC Internals & Extensibility

Eyal Vardi

CEO E4D Solutions LTD

Microsoft MVP Visual C#

blog: www.eVardi.com

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

Agenda

Routing

Dependency Resolver

Controller Extensibility

Model Extensibility

View Extensibility


MVC in ASP.NET


ASP.NET vs. ASP.NET MVC


MVC Execution Process

ASP.NET

IIS Routing ASP.NET

MVC 3.0


URL Routing

http://Domain/Path

http://Domain/.../..

URL to Controller

URL to Page


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() { RouteTable .Routes .MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL template new { controller="Calc", action="Add", id=UrlParameter.Optional } ); }

Global.asax


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"


URL Routing Pipeline


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() { 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” )

Global.asax


IRouteConstraint

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 = new MyRouteConstraint() } ); }

Custom Route Constraint

Global.asax


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


Route lifecycle


Route

IDependencyResolver

MvcRouteHandler MvcHandler Controller

Routing Process


Custom Route Constraint


Routing Summary

URL Templates Default values

Namespaces

Constraint

IRouteHandler

RouteBase


Dependency Resolver

Service locator for the framework.

protected void Application_Start() { ... DependencyResolver.SetResolver(new TraceDependencyResolver() ); }


Trace Dependency Resolver


Dependency Resolver


Controller Extensibility


Understanding Controllers

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


Controller Class


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.


Creation of the Controller

Routing

Controller

Factory

Controller

Activator Controller

Dependency

Resolver

MvcRouteHandler MvcHandler Request

Dependency

Resolver


How Controller Created?


Controller Summary

MvcHandler

IControllerFactory

IControllerActivator


The Action Execution

Routing

Controller

Factory

Controller


Action

Invoker

Action

Method

Dependency

Resolver

MvcRouteHandler MvcHandler Request

Dependency

Resolver



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.


Built-In Action Invoker

Finds a method that has the same name as the requested action.


Custom Action Name

You can then accept an action name that wouldn’t be legal as a C# method name. [ActionName("User-Registration")]

[ActionNameSelector]


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.


Custom Action Method Selector

You return true from IsValidForRequest if the method is able to process a request, and false otherwise.


Custom Method Selector


Handling Unknown Actions


Action Summary

IActionInvoker

Action Name Selector

Action Method Selector

Handling Unknown Actions


Model Extensibility


Model Binding

What Is a Model?

Model

Controller View HTTP HTML

Deserialization

Template


HTTP to .NET Classes

public ActionResult Index(Reservation reservation) { // TODO BL. return View( reservation ); }

Deserialization


HTTP to .NET Args


Model Binders

Binders are like type converters, because they can convert HTTP requests into objects that are passed to an action method.


DefaultModelBinder Class

Translate HTTP request into complex models, including nested types and arrays. URL

Form data, Culture - Sensitive

1. Request.Form

2. RoutedData.Values

3. Request.QueryString

4. Request.Files

(Key,Value)


Model Binder Types

ByteArrayModelBinder

LinqBinaryModelBinder

FormCollectionModelBinder

HttpPostedFileBaseModelBinder

DefaultModelBinder


Binding to Complex Types [DisplayName("Book")] public class E4DBook { [Display(Name = "Title")] public string E4DTitle { get; set; } public Reservation MyReservation { get; set; } }

Model

<label for="MyReservation_FlightNum">FlightNum</label> <input type="text" value="" id = "MyReservation_FlightNum" name = "MyReservation.FlightNum" />

Html

@Html.LabelFor(model => model.MyReservation.FlightNum) @Html.EditorFor(model => model.MyReservation.FlightNum)

View


Specifying Custom Prefixes

<!– First Arg --> <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" />

Html

public ActionResult Index( Reservation res1 , [Bind(Prefix="myRes")] Reservation res2 ) { ... }

Controller


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; } }


Bind Attribute


<input type="text" name="reservation" /> <input type="text" name="reservation" /> <input type="text" name="reservation" /> <input type="text" name="reservation" />

Html

public ActionResult Index( List< string > reservation ) { ... }

Controller

Binding to a String Collections


Binding to a Collections

<!– Option I--> <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" />

Html

public ActionResult Index( List<Reservation> reservation ) { ... }

Controller


Binding to a Dictionary

<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" />

Html

public ActionResult Index( Dictionary<Reservation> reservation ) { ... }

Controller


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() );


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(); }


Custom Binder


Model Summary

Http to .NET Classes

IModelBinder

IValueProvider

ModelMetadataProvider

BindAttribute

Validation

Data Annotations

IValidateObject


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


Custom Action Result


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(); } }


Action Method Action Result

Filter Interfaces


Filter Order

Filters run in the following order:

Authorization filters

Action filters

Response filters

Exception filters


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 controller's On<Filter> method. OnAuthorization

OnActionExecuting

OnActionExecuted

OnResultExecuting

OnResultExecuted

OnException


IAuthorizationFilter

Make security decisions about whether to execute an action method.

AuthorizeAttribute

RequireHttpsAttribute


IActionFilter Interface

OnActionExecuting Runs before the action method.

OnActionExecuted Runs after the action method


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.


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.


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


Action Method Action Result

First Global Controller Action Last

Filter I

Filter II

Filter I

Filter II

Filter I

Filter II

Filter I

Filter II

Filter I

Filter II

Action

Filter I

Filter I

Filter I

Filter I

Filter I

Filter I

Filter I

Filter I

Filter I

Filter I

Result

Filter I

Filter I

Filter I

Filter I

Filter I

Filter I

Filter I

Filter I

Filter I

Filter I

Exception

Filter II Filter II

Filter II Filter II

Filter II

Filter I Filter I

Filter I Filter I

Filter I

Authorization

Filter I Filter I

Filter I Filter I

Filter I

Filter II Filter II

Filter II Filter II

Filter II


Action

Before After

Filter I

Filter I

Filter I

Filter I

Filter I

Filter II

Filter II

Filter II

Filter II

Filter II

Filter II

Filter II

Filter II

Filter II

Filter II

Filter I

Filter I

Filter I

Filter I

Filter I


Controller Context

1

2 3 4 5

6


Filters


Custom Filter

You can create a filter in the following ways:

Override one or more of the controller's 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.


Custom Filter


The Filter Provider Interface


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.


Filter Summary

Custom Filters IAuthorizationFilter

IActionFilter

IResultFilter

IExceptionFilter

IFilterProvider


View Extensibility


Creating a Custom View Engine


View Summary

IViewEngine How to find the view?

IView Render


MVC Internals & Extensibility Summary

Routing

Controller

Factory

Controller


Action

Method

Dependency

Resolver

Mvc

RouteHandler MvcHandler

Dependency

Resolver

Authorization

Filter

Action

Filer

Result

Filter

Exception

Filter View

Action

Invoker Method

Selectror

Name

Selector

Model

Bind

Action

Filer

Result

Filter

View

Engine

Asp.net mvc internals & extensibility

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