Routing in ASP.NET MVC

Remember, browsers make HTTP requests

HTTP requests use a verb to communicate their intent

� GET � POST � PUT � DELETE

� asdf

Alright. Got that out of the way. Now back to our regularly-scheduled lecture.

Which is better? This …

http://www.tic.com/Report.aspx?

Type=Sales&year=2012&month=07!

… or this …

http://www.tic.com/Sales/2012/7!

Why?

Reasons � SEO � Easy to type � Easy to remember � Hides implementation stack � URLs don’t have to change when the site

changes. � Hackable

URLs point to resources. � Uniform ________________ locator � They don’t point to pages � So RESTful URLs are more accurate,

actually

REST is … � an architectural style … �  for addressing resources … �  in a stateless environment … �  that reduces coupling

A RESTful URL is one that conforms to all of the constraints � Separation between client and server � Stateless communication � Cacheable � A layered system � A uniform interface

A layered system has predictable parts

The usual method

Category

Thing

Action

ID

Properly RESTful url

Category

Thing

ID

(Use HTTP method as action)

Use the HTTP requests to specify the action

� GET � POST � PUT � DELETE

The URL should act as an API

� http://tic.com/Associate/List � http://tic.com/Associate/Create � http://tic.com/Associate/Details/71 � http://tic.com/Associate/Edit/71 � http://tic.com/Associate/Delete/71 � http://tic.com/Department � http://tic.com/Customer � http://tic.com/AddToCart/17

There are certain things you can do to make a URL RESTful � Give every “thing” an ID � Link things together � Use standard methods � Resources with multiple representations � Communicate statelessly

Give every thing an ID

� Easy to do if you're using a primary key and a database behind it

Link things together

� Also easy to do if you're using HTML

Use standard methods

Resources with multiple representations

� HTML � XML � VCard

Communicate statelessly � Aaaand yet again, the web makes this easy.

Okay, I'm sold on RESTful urls. How do I get them into MVC?

Registering routes tells IIS that if a user asks for X, send them to Y

We use the MapRoute() method to create these routes MyRoutes.MapRoute(! string RouteName,! string URL,! object Defaults);!� Says when URL comes through, what do

we do with it?

Routing in ASP.NET MVC are set in Application_Start � Pulled out into a static method by default. public static void RegisterRoutes(RouteCollection routes)!{! routes.IgnoreRoute("{resource}.axd/{*pathInfo}");! routes.MapRoute(! "Default", // Route name! "{controller}/{action}/{id}", // URL with parms! new { controller = "Home", action = "Index", ! id = UrlParameter.Optional } // defaults! );!}!

Routes are matched in order that they appear

These routes work for WebForms also � They're exactly the same.

Hardcoded routes are easy routes.MapRoute(! "ListAllProducts",! "Product/List",! "~/Admin/Products.aspx?id=all",! false! );!

Hands-on literal routes

We put placeholders in curly braces � aka. URL Parameters

Examples Route definition Example of matching url

{controller}/{action}/{category}

/Products/show/beverage

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

blog/{action}/{entry} blog/read/1234

{reportType}/{year}/{month}/{day}

/sales/2012/7/15

{locale}/{action} en-US/show

Hands-on matching routes

Optional parameters can save you from creating a lot of routes � Example: you want to match � Clients/Miller � Clients/Miller/Harold � Clients/Miller/Harold/Dr � … with the same route � Simply make first name and title optional

with: � new { FirstName = UrlParameter.Optional,

Title = UrlParameter.Optional }

Hands-on optional parameters

Hands-on default values

The parameters can have one of two types of constraints 1.  Regular expressions 2.  An IRouteConstraint

Regular expression constraints routes.MapRoute(! "BlogArchive",! "Archive/{entryDate}",! new { controller="Blog", action="Archive" }, ! new { entryDate=@"\d{2}-\d{2}-\d{4}" }!);!

Hands-on constraints

Conclusion � RESTful urls are easier to use, therefore

better � MVC lends itself well to REST; in fact REST is

pretty much required to get to controllers and actions

� Routes are set up in the global.asax file

Further study �  Intro to REST

�  http://www.infoq.com/articles/rest-introduction