ASP.NET Core MVC

ASP.NET Core MVC is a framework for building web applications that use the Model-View-Controller (MVC) pattern. This pattern separates concerns, making applications easier to maintain, test, and scale.

Key Concepts

Model

The Model represents the data and the business logic of the application. It's responsible for managing the data, responding to requests for information from the view, and updating the view when the data changes.

View

The View is responsible for presenting the data to the user. It typically contains HTML, CSS, and client-side scripts. In ASP.NET Core MVC, Views are often implemented using Razor syntax, which allows embedding C# code within HTML.

Controller

The Controller acts as an intermediary between the Model and the View. It receives user input, interacts with the Model to retrieve or update data, and then selects the appropriate View to display the results to the user.

Getting Started with ASP.NET Core MVC

To create an ASP.NET Core MVC application, you can use the .NET CLI or Visual Studio.

Using the .NET CLI:

dotnet new mvc -n MyMvcApp
cd MyMvcApp
dotnet run

This command creates a new MVC project named "MyMvcApp" and then runs it.

Core Components

Controllers

Controllers are classes that handle incoming requests. They contain actions, which are methods that perform specific tasks. For example, a controller might have an action to display a list of products or process a form submission.

Example Controller:

public class HomeController : Controller
{
    public IActionResult Index()
    {
        return View(); // Returns the Index.cshtml view
    }

    public IActionResult About()
    {
        ViewData["Message"] = "Your application description page.";
        return View();
    }
}
 Views

Views are responsible for the UI. They are typically Razor files (.cshtml) that combine HTML with C# code to dynamically generate content.

Example View (Views/Home/Index.cshtml):

<h1>Welcome!</h1>
<p>This is the homepage of your ASP.NET Core MVC application.</p>
 Models

Models represent the application's data. They can be simple Plain Old CLR Objects (POCOs) or more complex classes that include data validation logic and interact with a data source.

Example Model:

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
}
 Routing

Routing maps incoming request URLs to controller actions. ASP.NET Core MVC uses a convention-based routing system, but it can also be configured with attribute routing.

The default route template in Program.cs (or Startup.cs in older versions):

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

Important Note on MVC Lifecycle

Understanding the request lifecycle in ASP.NET Core MVC is crucial. A request travels through various middleware, routing, controller action invocation, model binding, action filters, and finally, view rendering.