How does routing work in ASP.NET MVC? Explain attribute routing.

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ICSM Computer · Answer

In ASP.NET MVC, routing is the mechanism that maps incoming URLs to
controller actions. It’s essential to delivering requests to the right code based on URL patterns.
1. Routing Table (Convention-Based Routing)
Defined in RouteConfig.cs (inside App_Start).
The application uses URL patterns to route requests.
Example:
routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
URL: /Products/Details/5 →
Maps to: ProductsController.Details(int id = 5)
This is convention-based routing — the route depends on the folder/controller/action structure.
2. Route Matching Process
When a request comes in:
MVC reads the routing table in order.It matches the request URL to the defined route pattern.It determines:
Which controller to instantiate.Which action method to invoke.What parameters to pass.
What is Attribute Routing?
Attribute Routing lets you define routes directly on controller actions using
[Route] attributes instead of relying on the centralized route table.
Introduced in ASP.NET MVC 5.
Enabling Attribute Routing
In RouteConfig.cs:
public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
    // Enable attribute routing
    routes.MapMvcAttributeRoutes();
    // (Optional) fallback conventional route
    routes.MapRoute(
        name: "Default",
        url: "{controller}/{action}/{id}",
        defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
    );
}
Example: Attribute Routing
public class ArticlesController : Controller
{
    [Route("articles/view/{id}")]
    public ActionResult ViewArticle(int id)
    {
        // Logic
        return View();
    }
    [Route("articles/delete/{id}")]
    public ActionResult DeleteArticle(int id)
    {
        // Logic
        return View();
    }
}
URL: /articles/view/10 → hits ViewArticle(10)
URL: /articles/delete/10 → hits DeleteArticle(10)
Attribute Routing with Constraints
[Route("blog/{year:int}/{month:int}/{title}")]
public ActionResult BlogPost(int year, int month, string title) { ... }
Adds validation to ensure only integers for year and month.
Benefits of Attribute Routing
Feature
Benefit
Clarity
Routes are defined next to the action methods
Flexibility
Easily create custom and SEO-friendly URLs
Control
No need to rely on one global route template
Support
Route constraints, optional params, defaults
Summary
Routing Type
Description
Convention-based
Central route pattern (e.g., {controller}/{action}/{id})
Attribute routing
Routes defined directly on actions using [Route]
Routing = URL → Controller + Action + Parameters

Routing Type	Description
Convention-based	Central route pattern (e.g., `{controller}/{action}/{id}`)
Attribute routing	Routes defined directly on actions using `[Route]`

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How does routing work in ASP.NET MVC? Explain attribute routing.

Anubhav Kumar

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1 Answers

1. Routing Table (Convention-Based Routing)

Example:

2. Route Matching Process

What is Attribute Routing?

Enabling Attribute Routing

Example: Attribute Routing

Attribute Routing with Constraints

Benefits of Attribute Routing

Summary

Liked By

Feature	Benefit
Clarity	Routes are defined next to the action methods
Flexibility	Easily create custom and SEO-friendly URLs
Control	No need to rely on one global route template
Support	Route constraints, optional params, defaults