Extending ASP.NET MVCPart 1

Simone ChiarettaArchitect, Council of the EUhttp://codeclimber.net.nzTwitter: @simonech

June 23rd, 2010

Who the hell am I?

► Simone Chiaretta► Microsoft MVP ASP.NET► ASP Insider► Blogger – http://codeclimber.net.nz ► Italian ALT.NET UG Founder► OpenSource developer► Climber► All Around Nice Guy

Disclaimer:"The views expressed are purely those of the speaker and may not in any circumstances be regarded as stating an official position of the Council"

Agenda

► The default ASP.NET MVC Pipeline► Extensibility points’ list► The Most important extensibility points

The Default ASP.NET MVC Pipeline

The default ASP.NET MVC Pipeline

Request

URLRouting

Route RouteHandler

HttpHandler

Controller Factory Controller

Action

ViewFactory View

Response

5

The default components

► URL Routing:– Parses the URL, and instantiate the MvcHandler

► Controller Factory– Takes URL parameters, create controller via reflection based on Controller name

► Action Invoker– Invokes the action based on the name, with the filters before and after

► View Engine– WebForms view engine

► Template– Renders a TextBox almost for everything

► HtmlHelper– Has a bunch of standard methods

ASP.NET MVC IS extensible

► If you don’t like them► If you need something else► Change them

ASP.NET MVC IS extensible

► Almost every aspect of the framework can be extented/replaced

Extensibility points’ list

Routing extensibility

► RouteConstraint– Validates route parameters with code

► RouteHandler– Defines how the request must be handled

Controller Extensibility

► ControllerFactory– Responsible for creating Controllers

► ActionInvoker– Invokes an action, based only on its name

► ActionMethodSelector Attribute– Helps the action invoker decide which action to invoke when the name is not unique

► Controller– The base class for every controller

► ActionResult– Decides how to send the output to the user

Action Filter Extensibility

► AuthorizationFilter– Makes sure the current request is allowed

► Action Filters– Executed before or after the action executes

► Result Filters– Executed before or after an action result executes

Binding/Validation Extensibility

► ModelBinder– Populates the action method parameters from the request

► ModelValidator Provider– Retrieves the validation rules

► Server-side Validation Rules– The actual server-side validation rule

View Extensibility

► ViewEngine– The service that transforms in HTML the data for the user

► HtmlHelpers– Utility functions that hide away the generation of some HTML markup or JavaScript code

► Client-side Validation Rules– Client-side validation rules

► ModelMetadata Provider– Retrieves the metadata needed for the templated helpers

► Custom Templates– Renders the html to edit/display specific types

The Most important extensibility points

The Most important Extensibilit points► The ones you will definitely use► The ones you have to start using► The ones you might or might not need to use

► The ones you most likely will not write yourself– but probably use written by others

Extensibility points you will use

Custom Templates

Custom Templates

► WHAT: Renders the html to edit/display specific types

► DEFAULT: Everything is a label or a textbox

► WHY: Add your own to customize specific data-types

Custom Templates

► Add PartialViews in:– /Views/Shared/DisplayTemplates– /Views/Shared/EditorTemplates

Demo

Server-side Validation Rules

Server-side Validation Rules

► WHAT: Define how a property is validated in the server side validation

► DEFAULT: Required, Length, wrong type► WHY: Add your own rules

Server-side Validation Rules

► Write a new ValidationAttribute► Implement the IsValid method► Apply attribute to your model

Demo

Client-side Validation Rules

Client-side Validation Rules

► WHAT: Define how a property is validated in the client-side validation

► DEFAULT: Client-side counterparts of the default server-side validators

► WHY: Add your own validators

Client-side Validation Rules

► First make a server-side validator► Make validation logic in JavaScript► Write adapter to push validation rules to client-side

► Register validation function via JS► Register adapter in Global.asax

Demo

Extensibility points you have to start using

Base Controller

Base Controller

► WHAT: The base class for every Controller► DEFAULT: Default implementation of helper methods

► WHY: Extend if you want to enforce you own conventions

Base Controller

► Override Controller► Your controllers override from BaseController instead of Controller

Demo

HtmlHelpers

HtmlHelpers

► WHAT: Utility functions that hide away the generation of HTML markup or JavaScript code

► DEFAULT: Html.TextBox, Html.Encode, Html.Partial, …

► WHY: “If there is an if, write an Helper”

HtmlHelpers

► Add new methods as extension methods

Demo

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34 Disclaimer:"The views expressed are purely those of the speaker and may not in any circumstances be regarded as stating an official position of the Council"

Extending ASP.NET MVCPart 2

Simone ChiarettaArchitect, Council of the EUhttp://codeclimber.net.nzTwitter: @simonech

June 23rd, 2010

Filters

Authorization Filter

► WHAT: Makes sure the current request is allowed

► DEFAULT: It is based on the ASP.NET Membership provider

► WHY: Change if you want not to use ASP.NET MVC or if you want to enhance the route dictionary

Action Filters

► WHAT: Executed before or after the action executes

► DEFAULT: Output cache► WHY: Add your own based on your needs

Result Filters

► WHAT: Executed before or after an action result executes

► DEFAULT: No default result filters► WHY: Add your own based on your needs

Authorization Filter

► Implement IAuthorizationFilter– OnAuthorization

Filters

► Implement IActionFilter + IResultFilter► Make new ActionFilterAttribute

– OnActionExecuting– OnActionExecuted

► Implement IResultFilter– OnResultExecuting– OnResultExecuted

Extensibility points you might want to use

RouteConstraint

RouteConstraint

► WHAT: Validates route parameters► DEFAULT: No default implementation► WHY: Add your own when needed

RouteConstraint

► Implement– IRouteConstraint.Match

► Inspect request and return true or false

Demo

RouteHandler

RouteHandler

► WHAT: Defines how the request must be handled

► DEFAULT: Routes the request to MvcHandler► WHY: Change if you want not to use ASP.NET MVC

RouteHandler

► Implement– IRouteHandler.GetHttpHandler

Demo

ActionMethodSelector Attribute

ActionMethodSelector Attribute

► WHAT: Helps the action invoker decide which action to invoke when the name is not unique

► DEFAULT: HttpMethod attributes: decide based on the HttpMethod

► WHY: Add your own to support different scenarios

ActionMethodSelector Attribute

► Create new Attibute inheriting from– ActionMethodSelectorAttribute

► Implement:– IsValidForRequest

Demo

ActionResult

ActionResult

► WHAT: Sends the output to the user► DEFAULT: ViewResult, RedirectResult, FileResult, JsonResult, etc…

► WHY: Add your own if you need an output not available in the default results

ActionResult

► Create a new result inheriting from:– ActionResult

► Implement:– ExecuteResult

► Optionally create an helper method in you “base controller”

Demo

ModelBinder

ModelBinder

► WHAT: Populates the action method parameters from the request

► DEFAULT: Binds request’s values based on names

► WHY: Extend if you need to add other way of binding

ModelBinder

► Implement IModelBinder– BindModel

► Inherit from DefaultModelBinder– BindProperty– OnModelUpdated– OnModelUpdating

► Register the ModelBinder

Demo

Very unlikely to write your own

ControllerFactory

Controller Factory

► WHAT: Responsible for creating Controllers► DEFAULT: Create an instance of the Controller via Reflection based on its name

► WHY: Change if you want to create the controller in other ways or if you want to add some funtionalities

► Most of the main IoC container have a custom ControllerFactory

Controller Factory

► Implement IControllerFactory– CreateController– ReleaseController

► Override DefaultControllerFactory– GetControllerInstance(Type controllerType)

Demo

ActionInvoker

ActionInvoker

► WHAT: Invokes an action, based only on its name

► DEFAULT: Call the action method, via reflection, based on its name, gathering filters via attributes and calling them before and after

► WHY: Change if you want to change the way methods are called, or want different way to configure Filters

ActionInvoker

► Implement IActionInvoker– InvokeAction

► Override ControllerActionInvoker– InvokeActionMethodWithFilters– InvokeActionResultWithFilters– GetFilters– …

Demo

ViewEngine

View Engine

► WHAT: The service that transforms in HTML the data for the user

► DEFAULT: WebForm view engine► WHY: Change if you don’t like the WebForm approach

View Engine

► IViewEngine:– Usually override VirtualPathProviderViewEngine– CreateView

► IView:– Render

Demo

ModelValidator Provider

ModelValidator Provider

► WHAT: Retrieves the validation rules► DEFAULT: Validation rules are defined with DataAnnotation attributes

► WHY: Change if you want to specify validation rules in other ways (XML, Database, etc…)

ModelValidator Provider

► Override from ModelValidatorProvider► Implement GetValidators

ModelMetadata Provider

ModelMetadata Provider

► WHAT: Retrieves the metadata needed for the templated helpers

► DEFAULT: Metadata are defined with DataAnnotation attributes

► WHY: Change if you want to specify metadata in other ways (XML, Database, etc…)

ModelMetadata Provider

► Inherit from ModelMetadataProvider► Implement

– GetMetadataForType– GetMetadataForProperty– GetMetadataForProperties

Contacts – Simone Chiaretta

► MSN: simone_ch@hotmail.com► Blog:

– English: http://codeclimber.net.nz/– Italian: http://blogs.ugidotnet.org/piyo/

► Twitter: @simonech

74

Rating

If you liked this talk, please consider rating it:

http://speakerrate.com/talks/3669-asp-net-mvc-extensibility

75 Disclaimer:"The views expressed are purely those of the speaker and may not in any circumstances be regarded as stating an official position of the Council"