Introduction to Routing in .NET MVC

Routing is the backbone of the .NET MVC web application, determining how URLs map to controller actions. In this article, we will explore the different routing approaches available, from default routing to more advanced attribute-based routing, equipping you with the knowledge to create intuitive and flexible URL structures.

Table of Contents

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Convention-based

The default routing in .NET MVC follows a convention-based approach, where the URL structure maps directly to the controller and action names.

URL Pattern

Conventional routing follows a specific URL pattern, such as:

{controller}/{action}/{id}

Define the default Route

.NET MVC provides a MapRoute method to define the default route.

// Define the default route
routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);

Here, the name of the route is Default. The URL pattern is {controller}/{action}/{id} which means the URL contains the controller name, action name and an optional parameter.

Route Generation

The routing engine automatically generates the appropriate URL based on the controller and action names.

Attribute Routing

Attribute routing allows you to define your routes directly on the controller and action methods. This approach gives you more granular control over your URL structure and routing logic. Attribute routing enables the creation of more meaningful and intuitive URLs for your web application.

Defining Routes with Attributes

Let’s take a look at defining attribute routing in .NET MVC:

[Route("sports/home")]
public async Task<IActionResult> Index(int pageNumber = 1, int pageSize = 25)
{
    var articles = await _pilotService.SportsPageContent(2, pageNumber, pageSize);
    return View(articles);
}

In this example, the routes would be:

/sports/home for Index action.

Route Parameters

Attribute routing supports URL parameters, allowing you to extract values from the URL and pass them to the action method.

[Route("article/{id}")]
public async Task<IActionResult> Index(string id)
{
    var articles = await _pilotService.LoadContent(id);
    return View(articles);
}

Here, {id} is the parameter of the web page URL.

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Route Constraints in .NET MVC

MVC provides Route Constraints to restrict to match a route for a given URL on the basis of route parameters.

Basic Route Constraints

In this example, we will create routes with constraints on the parameter values.

[Route("products/details/{id:int}")]
public ActionResult Details(int id)
{
    return View();
}

Types of Route Constraints in .NET MVC

Regex Constraints

Regular expression constraints allow you to enforce specific patterns for route parameters.

Data Type Constraints

You can constrain route parameters to specific data types, such as int, decimal, or guide.

Custom Constraints

Developers can create their own custom route constraints to enforce complex business rules.

Conclusion and Best Practices

Default Routing: Use for simple, convention-based URL structures
Attribute Routing: Leverage for more complex, customized URL requirements
Routing Constraints: Implement to enforce business rules and maintain data integrity

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