Asp.Net Core Conventional Vs Attribute Routing Complete Guide

Step-by-Step Guide

1. Create a new ASP.NET Core Web Application

First, let's create a new ASP.NET Core Web Application project. You can do this with Visual Studio or using the .NET CLI.

Using Visual Studio:

• Open Visual Studio.
• Click on Create a new project.
• Choose ASP.NET Core Web App (Model-View-Controller).
• Click Next.
• Configure your project name and location.
• Click Create.
• Select .NET 6.0 (Long-term support) or later as your target framework.
• Click Create.

Using .NET CLI:

• Open your command line interface (CLI).
• Navigate to the directory where you want to create the project.
• Run the following command:

  dotnet new mvc -o ConventionalVsAttributeRoutingExample
  cd ConventionalVsAttributeRoutingExample
  

2. Set Up Conventional Routing

In ASP.NET Core, conventional routing is configured usually in the Program.cs (or Startup.cs for older versions). By default, the MVC template sets up conventional routing for us in Program.cs.

Let's ensure the conventional routing set up:

Open Program.cs:

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddControllersWithViews();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Home/Error");
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthorization();

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

app.Run();

This setup configures conventional routing using the route template {controller=Home}/{action=Index}/{id?}. This means:

• The default controller is Home.
• The default action is Index.
• The id segment is optional.

3. Create a New Controller with Conventional Routing

Let's create a ProductController that we'll access via conventional routing.

Create ProductController.cs: Navigate to the Controllers folder and add a new controller class.

using Microsoft.AspNetCore.Mvc;

public class ProductController : Controller
{
    public IActionResult Index()
    {
        return View("Index", new List<string> { "Laptop", "Smartphone", "Tablet" });
    }

    public IActionResult Details(int id)
    {
        var products = new Dictionary<int, string>
        {
            { 1, "Laptop" },
            { 2, "Smartphone" },
            { 3, "Tablet" }
        };

        if (products.TryGetValue(id, out var productName))
        {
            ViewBag.ProductName = productName;
            return View();
        }

        return NotFound();
    }
}

Create Views: Now, navigate to the Views folder and create a Product folder inside it. Inside this folder, add two views: Index.cshtml and Details.cshtml.

Index.cshtml:

@model IEnumerable<string>

<h2>Product List</h2>
<ul>
@foreach (var product in Model)
{
    <li>@product</li>
}
</ul>

<h3>Link to individual Products:</h3>
<ul>
<li><a href="/Product/Details/1">Laptop</a></li>
<li><a href="/Product/Details/2">Smartphone</a></li>
<li><a href="/Product/Details/3">Tablet</a></li>
</ul>

Details.cshtml:

<h2>Product Details</h2>
<p>Product Name: @ViewBag.ProductName</p>
<a href="@Url.Action("Index")">Back to List</a>

4. Set Up Attribute Routing

Attribute routing allows us to specify routes directly over actions within the controller. Let's modify our HomeController to use attribute routing.

Open HomeController.cs: Add the [Route] attribute above the controller class and [HttpGet] or other specific HTTP method attributes above the actions.

using Microsoft.AspNetCore.Mvc;

[Route("[controller]/[action]")]
public class HomeController : Controller
{
    [HttpGet]
    public IActionResult Index()
    {
        return View();
    }

    [HttpGet]
    public IActionResult AboutUs()
    {
        return View();
    }

    [HttpGet("{id}")]
    public IActionResult Customer(int id)
    {
        ViewBag.CustomerId = id;
        switch (id)
        {
            case 1:
                ViewBag.CustomerName = "John Doe";
                break;
            case 2:
                ViewBag.CustomerName = "Jane Smith";
                break;
            default:
                ViewBag.CustomerName = "Unknown";
                break;
        }
        return View();
    }
}

Create Views: Ensure you have views Index.cshtml, AboutUs.cshtml, and Customer.cshtml in the Views/Home folder.

Index.cshtml:

<h2>Welcome to Home Page</h2>
<a href="/Home/AboutUs">Go to About Us</a>
<a href="/Home/Customer/1">Customer John Doe Info</a>

AboutUs.cshtml:

<h2>About Us</h2>
<p>This is our About Us page.</p>
<a href="@Url.Action("Index", "Home")">Back Home</a>

Customer.cshtml:

<h2>Customer Details</h2>
<p>Customer ID: @ViewBag.CustomerId</p>
<p>Customer Name: @ViewBag.CustomerName</p>
<a href="@Url.Action("Index", "Home")">Back Home</a>

5. Combine Both Routing Methods

You can also combine these methods to use both conventional and attribute routing in the same application.

For example, we can keep the ProductController using conventional routing but add some actions with attribute routing.

Modify ProductController.cs:

using Microsoft.AspNetCore.Mvc;

public class ProductController : Controller
{
    [HttpGet]
    [Route("store/[action]")]
    public IActionResult Catalog()
    {
        return View("Catalog", new List<string> { "Headset", "Mouse", "Keyboard" });
    }

    public IActionResult Index()
    {
        return View("Index", new List<string> { "Laptop", "Smartphone", "Tablet" });
    }

    public IActionResult Details(int id)
    {
        var products = new Dictionary<int, string>
        {
            { 1, "Laptop" },
            { 2, "Smartphone" },
            { 3, "Tablet" }
        };

        if (products.TryGetValue(id, out var productName))
        {
            ViewBag.ProductName = productName;
            return View();
        }

        return NotFound();
    }
}

Create Catalog view: Inside Views/Product, add a file named Catalog.cshtml.

Catalog.cshtml:

@model IEnumerable<string>

<h2>Store Catalog</h2>
<ul>
@foreach (var product in Model)
{
    <li>@product</li>
}
</ul>

<h3>Link to individual Products:</h3>
<ul>
<li><a href="/store/details/1">Catalog Laptop</a></li>
<li><a href="/store/details/2">Catalog Smartphone</a></li>
<li><a href="/store/details/3">Catalog Tablet</a></li>
</ul>

Now, the Catalog action in the ProductController uses attribute routing with the route template store/[action].

6. Build and Run the Project

Once you've set up both types of routing, let's build and run the project to see the results.

Using Visual Studio:

• Click on the Run button, or press F5, to start debugging the application.
• Observe the browser URL and the response generated.
• Try visiting /Home/Index, /Home/AboutUs, /Home/Customer/1, /Product/Index, /Product/Details/1, and /store/catalog.

Using .NET CLI:

• Run the following command to build and launch the application: