How to use and configure routing in ASP .NET 8?

 Routing in ASP.NET 8 is used to define how URL requests are mapped to controller actions or Razor pages. ASP.NET Core uses endpoint routing, which provides a unified approach to handling routes for MVC, Razor Pages, and other endpoint types. Here’s a comprehensive guide on how to use and configure routing in ASP.NET 8:

Configuring Routing in ASP.NET 8

  1. Basic Routing Setup:

    • Routing is typically configured in the Program.cs file using the MapControllerRoute, MapRazorPages, or MapEndpoints methods.
    csharp

    var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.UseRouting();

app.UseEndpoints(endpoints =>
{
    endpoints.MapControllerRoute(
        name: "default",
        pattern: "{controller=Home}/{action=Index}/{id?}");

    endpoints.MapRazorPages();
});

app.Run();

1. Routing in MVC

Defining Routes in MVC

  • Default Route:

    • The default route pattern is {controller=Home}/{action=Index}/{id?}.
    csharp

    app.UseEndpoints(endpoints =>
{
    endpoints.MapControllerRoute(
        name: "default",
        pattern: "{controller=Home}/{action=Index}/{id?}");
});

  • Custom Routes:

    • You can define custom routes as needed.
    csharp

    app.UseEndpoints(endpoints =>
{
    endpoints.MapControllerRoute(
        name: "blog",
        pattern: "blog/{articleId:int}",
        defaults: new { controller = "Blog", action = "Article" });
});

Controller Actions

  • Define actions in controllers to handle routes.

    csharp

    public class HomeController : Controller
{
    public IActionResult Index()
    {
        return View();
    }

    public IActionResult About()
    {
        return View();
    }

    public IActionResult Article(int articleId)
    {
        // Fetch and display the article
        return View();
    }
}

2. Routing in Razor Pages

Basic Razor Pages Routing

  • Automatic Routing:

    • Razor Pages automatically map URLs to Razor files in the Pages directory.
    csharp

    app.UseEndpoints(endpoints =>
{
    endpoints.MapRazorPages();
});

  • Custom Routes:

    • You can customize routes using the @page directive.
    html

    @page "/custom-route"
@model YourNamespace.Pages.CustomPageModel

<h1>Custom Route Page</h1>

PageModel Class

  • Define the PageModel class for the Razor Page.

    csharp

    public class CustomPageModel : PageModel
{
    public void OnGet()
    {
        // Handle GET request
    }
}

3. Attribute Routing

  • Attribute routing allows you to define routes directly on controller actions.

Using Attribute Routing

  • Controller Actions:

    csharp

    [Route("products")]
public class ProductsController : Controller
{
    [Route("")]
    [Route("index")]
    public IActionResult Index()
    {
        return View();
    }

    [Route("{id:int}")]
    public IActionResult Details(int id)
    {
        // Fetch product by id
        return View();
    }
}

  • Route Prefix:

    csharp

    [Route("admin")]
[Route("[controller]")]
public class AdminController : Controller
{
    [Route("dashboard")]
    public IActionResult Dashboard()
    {
        return View();
    }
}

4. Advanced Routing Features

Route Constraints

  • Define constraints to restrict route parameters.

    csharp

    app.UseEndpoints(endpoints =>
{
    endpoints.MapControllerRoute(
        name: "default",
        pattern: "{controller=Home}/{action=Index}/{id:int?}");
});

Route Data Tokens

  • Data tokens provide additional data for routes.

    csharp

    app.UseEndpoints(endpoints =>
{
    endpoints.MapControllerRoute(
        name: "areaRoute",
        pattern: "{area:exists}/{controller=Home}/{action=Index}/{id?}",
        defaults: new { area = "Admin" });
});

Route Prioritization

  • Define the order of routes to handle priorities.

    csharp

    app.UseEndpoints(endpoints =>
{
    endpoints.MapControllerRoute(
        name: "blog",
        pattern: "blog/{articleId:int}",
        defaults: new { controller = "Blog", action = "Article" });

    endpoints.MapControllerRoute(
        name: "default",
        pattern: "{controller=Home}/{action=Index}/{id?}");
});

Summary

  • Basic Configuration: Set up routing in Program.cs using UseRouting and UseEndpoints.
  • MVC Routing: Use MapControllerRoute for defining routes to controllers.
  • Razor Pages Routing: Use MapRazorPages for automatic routing to Razor Pages.
  • Attribute Routing: Define routes using attributes directly on controller actions.
  • Advanced Features: Use constraints, data tokens, and route prioritization for more control.

By following these guidelines, you can effectively configure and use routing in ASP.NET 8 to manage URL requests and map them to the appropriate handlers in your application.

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