ASP.NET Routing & MVC

Emad Alashi
ASP.NET/IIS MVP
Jordev
Readify
www.DotNetArabi.com
www.EmadAshi.com
@emadashi

URL Routing & MVC
ALL YOUR URL ARE BELONG TO YOU!

Agenda
• Why understanding Routing is important
• What is Routing?
• How it works
• How to test it
• Best Some practices

Why understanding Routing
• The entry to your web app
• HyperTextTransferProtol
• Strongly relates to Binding
• Never stay in doubt

History
/store/products.aspx?key=value
Store Page life cycle

QueryString*“..”+
Products.aspx

Handlers
Store/products/apples

• Parse
• Extract variables OtherHttpHandler

• Route to Handler URL

MVCHttpHandler

Handlers
Options?
• Rigid (absolute string comparison):
e.g. “http://store/products/view” ===> invoke method “view” in class “products”

• Pattern base:
1. http://store/{classX}/{methodY} ===> use MvcHttpHandler => Invoke method “Y” in class “X”
2. http://p/sub}/{module} ===> use MagicHttpHandler => invoke crazy code

Priority
We have to choose between patterns!
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/",
defaults: new { controller = "Home", action = "Index"}
);
routes.MapRoute(
name: "My2ndRoute",
url: "special{awesome}Pattern/{anotherVariable}",
defaults: new { awesome = "magic"}
);

Segmentation
http://store.com/home/index

First segment Second segment

Static words
“,controller- /,action-”
“home/index”
“anything/willdo”
=============================
“abc,controller- / ,action-”
“abchome / whatever”
==================
“abc,controller- / ,action-”
“home / whatever”

RouteData.Values
“,controller}/{action-/,id-”
“product/index/3”

Variable value
controller Product
action Index
id 3

Defaults
Or Defaults: Variable Value
“product/index” controller Product

? action Index
routes.MapRoute( id
Id !
3

name: "Default",

url: "{controller}/{action}/{id}",

defaults: new { id=3 }

);

UrlParameter.Optional
routes.MapRoute(

name: "Default",

url: "{controller}/{action}/{id}", Variable value
defaults: new {action = "Index“, id=UrlParameter.Optinal} controller Product

); action Index
id 3
• Supplied: “product/index/3”
• Not supplied: Variable value
“product/index” controller Product
action index

No excessive number of segments
“,controller-/,action-/,id-”
“products/oranges/edit/3”
Unless:
“,controller}/{action}/{id}/{*catchall-”
“product/oranges/edit/3/something’
Variable value
controller Product
action Index
id edit
Catchall 3/something

Constraints
1. Regular Expressions:
routes.MapRoute( name: "Default", url: "{controller}/{action}/{id}", …

constraints: new { controller = "^H.*" } );
2. Specific values:
constraints: new { action = "^Index$|^About$*" }
3. HTTP methods:
constraints: new { httpMethod= new HttpMethodConstraint("GET") }
4. Custom constraints:

bool IRouteConstraint.Match(HttpContextBase, Route, stringParameterName, RouteValueDictionary,
RouteDireciont)

Notes (Incoming)
• Reserved custom variables: “controller, action, area”
• routes.RouteExistingFiles = true;
• routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
• Last segment includes the QueryString

How Routing works
(Outgoing)

Helpers
1. Html.ActionLink(text, nameOfAction, nameOfController, RouteValues, HtmlAttributes)
2. Url.Action(text, nameOfAction, nameOfController, RouteValues)
3. @Html.RouteLink(text, RouteValues, HtmlAttributes)
4. Url.RouteLink(text, AnonymouseTypeValues)

• You can use Route name

Rules
1. All variables should have values: “,controller-/,action-/,id-”
a) Supplied
b) Current request
c) Default values

2. Should not dis-agree with default-only variables:
routes.MapRoute("MyRoute", "{controller}/{action}", new { myVar = "true" });

3. Satisfy constraints

Notes (Outgoing)
• Tricky: Reuse values of the current request URL:
url: "{controller}/{action}/{id}/{forth}",

defaults: new { controller = "Home", action = "Index", id = 3, forth=8},
------------
@Html.ActionLink("this is the link", "Index", new {id=5 });
@Html.ActionLink("this is the link", "Index", new {forth=8 });

• Url’s generated will try to produce the shortest url

Areas
public class AdminAreaRegistration : AreaRegistration {
public override string AreaName { get {
return "Admin"; } }
public override void RegisterArea(AreaRegistrationContext context)
{
context.MapRoute(
"Admin_default",
"Admin/{controller}/{action}/{id}",
new { action = "Index", id = UrlParameter.Optional }
);
}
}

Areas
AreaRegistration.RegisterAllAreas();

RouteConfig.RegisterRoutes(RouteTable.Routes);

Unit-Testing Routes (Incoming)
What do we want to test?

That the url patterns we want to support in our web app would populate the RouteData variables
as expected.

• Incoming:
• HttpRequestBase
• HttpContextBase
• HttpResponseBase

• Outcoing:
• +
• UrlHelper


Demo


MvcContrib
http://mvccontrib.codeplex.com/

"~/Products/View/44/offer".ShouldMapTo<ProductsController>(action => action.View(44, “offer"));

Design Guidelines
• Content vs Implementation
• Human friendly: content titles vs id’s
• Hackable
• Sense of hierarchy
• Static strings at the beggning of routes
• Dash instead of underscore
• Not too long
• Avoid complexity
• Be consistent

ASP.NET

It’s all open source!
http://aspnetwebstack.codeplex.com/

Q&A

www.emadashi.com
@EmadAshi

ASP.NET Routing & MVC

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