Model-View-Controller (MVC) in ASP.NET Core

The Model-View-Controller (MVC) architectural pattern separates an application into three interconnected components: the Model, the View, and the Controller. This separation of concerns helps manage the complexity of web applications. ASP.NET Core MVC provides a robust framework for building these applications.

What is MVC?

• Model: Represents the application's data and business logic. It's responsible for retrieving, storing, and manipulating data.
• View: Represents the user interface (UI) of the application. It displays data to the user and sends user input to the Controller. In ASP.NET Core, Views are typically written using Razor syntax.
• Controller: Acts as an intermediary between the Model and the View. It handles user input, interacts with the Model to retrieve or update data, and selects the appropriate View to display the results.

Key Concepts in ASP.NET Core MVC

Controllers

Controllers are C# classes that inherit from Controller. They contain action methods, which are public methods that handle incoming HTTP requests. Each action method typically corresponds to a specific task or functionality in the application.

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

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

Views

Views are typically implemented as .cshtml files, which combine HTML markup with C# code using the Razor syntax. They are responsible for rendering the UI and displaying data passed from the Controller.

@* Views/Home/Index.cshtml *@
@{
    ViewData["Title"] = "Home Page";
}


    
ASP.NET Core MVC
    
Welcome to your new ASP.NET Core MVC application!



    

        
Application uses
        

            
Sample pages using HTML, CSS, and JavaScript
            
Tag Helpers
            
Model binding
            
Client-side validation
        
    
    

        
Build tools
        

            
See the .csproj file for a list of NuGet packages.
            
Dynamically content generated by ASP.NET Core.
            
Web SDK and .NET CLI for building and publishing.
        
    
    

        
Overview
        
Learn more about ASP.NET Core at https://docs.microsoft.com/aspnet/core.
    

Models

Models can be simple C# classes (POCOs) that represent the data structure of your application. They can also include validation logic and methods for data access.

public class MessageViewModel
{
    public string Title { get; set; }
    public string Content { get; set; }
}

Routing

Routing in ASP.NET Core MVC maps incoming HTTP requests to specific action methods on Controllers. This is typically configured in the Startup.cs file using middleware like MapControllerRoute.

// In Startup.cs
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    // ...
    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllerRoute(
            name: "default",
            pattern: "{controller=Home}/{action=Index}/{id?}");
    });
    // ...
}

Further Reading

• Controllers in ASP.NET Core MVC
• Views in ASP.NET Core MVC
• Models in ASP.NET Core MVC
• Routing in ASP.NET Core MVC