MVC Architecture

60 min

MVC (Model-View-Controller) is a design pattern that separates an application into three main components, enabling organized, maintainable code. The MVC pattern promotes separation of concerns: models handle data and business logic, views handle presentation, and controllers handle user input and coordination. This separation makes applications easier to test, maintain, and extend. Understanding MVC is fundamental to ASP.NET Core development. MVC is one of the most widely used architectural patterns in web development.

Models represent the data and business logic of the application, defining data structures, validation rules, and business operations. Models are typically classes that represent entities in your application (users, products, orders). They can include data annotations for validation, relationships with other models, and methods for business logic. Understanding models enables you to structure your application's data layer. Models are the foundation of your application's data structure.

Views handle the display and user interface, rendering HTML to present data to users. Views in ASP.NET Core use Razor syntax, which combines HTML with C# code. Views receive data from controllers via ViewBag, ViewData, or strongly-typed models. Views should contain minimal logic—mostly presentation. Understanding views enables you to create user interfaces. Views are templates that generate HTML responses.

Controllers process user input and coordinate between models and views, handling HTTP requests and returning responses. Controllers contain action methods that respond to specific URLs and HTTP verbs (GET, POST, etc.). Controllers retrieve data from models, process requests, and return views or data. Understanding controllers enables you to handle user interactions. Controllers are the entry point for user requests.

MVC benefits include separation of concerns (easier maintenance), testability (components can be tested independently), scalability (components can be scaled independently), and team collaboration (different developers can work on different components). Understanding MVC benefits helps you appreciate the pattern. MVC is particularly powerful for large applications where organization matters.

Best practices include keeping controllers thin (delegate to services), keeping views simple (minimal logic), keeping models focused (single responsibility), using ViewModels for complex views, and following naming conventions. Understanding MVC best practices enables you to build maintainable applications. MVC is powerful when used correctly but can become messy if not organized properly.

Key Concepts

MVC separates application into Model, View, and Controller components.
Models represent data and business logic.
Views handle display and user interface.
Controllers process user input and coordinate between models and views.
MVC promotes separation of concerns and maintainability.

Learning Objectives

Master

Understanding MVC architecture and its components
Creating models, views, and controllers
Coordinating between MVC components
Following MVC best practices

Develop

Understanding architectural patterns
Designing maintainable application structure
Appreciating MVC's benefits for web development

Tips

Keep controllers thin—delegate business logic to services.
Use ViewModels for complex views instead of passing models directly.
Keep views simple—minimal logic, mostly presentation.
Follow naming conventions (Controllers end with 'Controller', Views match action names).

Common Pitfalls

Putting business logic in controllers, making them hard to test.
Putting business logic in views, violating separation of concerns.
Not using ViewModels, passing complex models to views.
Not following MVC conventions, making code hard to navigate.

Summary

MVC separates application into Model, View, and Controller components.
Models handle data, views handle presentation, controllers handle coordination.
MVC promotes separation of concerns and maintainability.
Understanding MVC enables building organized, maintainable applications.
MVC is fundamental to ASP.NET Core development.

Exercise

Create a simple MVC application with a controller that returns a view with a message.

// HomeController.cs
using Microsoft.AspNetCore.Mvc;

public class HomeController : Controller
{
    public IActionResult Index()
    {
        ViewBag.Message = "Welcome to ASP.NET Core MVC!";
        return View();
    }
}

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

<h1>@ViewBag.Message</h1>

MVC Architecture