Asp.Net Mvc Internals & Extensibility

MVC Internals &
Extensibility

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

Agenda
 Routing

 Dependency Resolver

 Controller Extensibility

 Model Extensibility

 View Extensibility

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MVC in ASP.NET


MVC Execution Process
ASP.NET

IIS Routing ASP.NET
MVC 3.0


URL Routing
URL to Page
http://Domain/Path

URL to Controller

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


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 }
);
}


Route lifecycle


Routing Process

Route MvcRouteHandler MvcHandler Controller

IDependencyResolver


URL Patterns
Route definition Example of matching URL
{controller}/{action}/{id} /Products/show/beverages

{table}/Details.aspx /Products/Details.aspx

blog/{action}/{entry} /blog/show/123

{reporttype}/{year}/{month}/{day} /sales/2008/1/5

{locale}/{action} /US/show

{language}-{country}/{action} /en-US/show


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"


Adding Constraints to Routes
 Constraints are defined by using regular
expressions string or by using objects that
implement the IRouteConstraint interface.
{
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” )


IRouteConstraint
{
RouteTable
.Routes
.MapRoute(
new { controller="Calc", action="Add", id=UrlParameter.Optional },
new { action = new MyRouteConstraint() }
);
}
Custom Route Constraint


Regular Expression Route
Constraint
protected void Application_Start()
{
RouteTable
.Routes
.MapRoute(
new { controller="Calc", action="Add", id=UrlParameter.Optional },
new { action = @"d{2}-d{2}-d{4}" }
);
}
Regular Expression


Custom Route
Constraint


Dependency Resolver
 Service locator for the framework.
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
RegisterGlobalFilters(GlobalFilters.Filters);
RegisterRoutes(RouteTable.Routes);

DependencyResolver
.SetResolver(new TraceDependencyResolver() );
}


Factories and Providers


Dependency Resolver


Controller Extensibility


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


Action Method 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
{
[HandleError]
[OutputCache]
[RequireHttps]
public ActionResult Net( string name )
{
ViewBag.Course = BL.GetCourse(name);
return View();
}
}

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.


Filter Order
 Filters run in the following order:
 Authorization filters

 Action filters

 Response filters

 Exception filters


Controller Context
1 6

2 3 4 5


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


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.


The Filter Provider Interface


Model Extensibility


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


Model Binder Types
 ByteArrayModelBinder

 LinqBinaryModelBinder

 FormCollectionModelBinder

 HttpPostedFileBaseModelBinder

 DefaultModelBinder


DefaultModelBinder Class
 Translate HTTP request
information into complex
models, including nested
types and arrays.

 It does this through a naming
convention, which is supported at
both the HTML generation (HTML
helpers) and the consumption side
(model binders).


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


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();
}


View Extensibility


Asp.Net Mvc Internals & Extensibility

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