ASP.NET Core MVC

ASP.NET Core MVC is a high-performance, cross-platform framework for building modern, cloud-enabled, internet-connected applications. It's a lightweight, open-source, and extensible framework based on the Model-View-Controller (MVC) design pattern.

What is MVC?

The Model-View-Controller (MVC) architectural pattern separates an application into three interconnected components:

Model: Represents the data and business logic of the application. It interacts with the data store and exposes data to the View.
View: Represents the user interface (UI) of the application. It's responsible for displaying the data provided by the Model in a user-friendly format. Views are typically Razor files (.cshtml).
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 render.

Key Features of ASP.NET Core MVC

Razor View Engine: A powerful and flexible templating engine for creating dynamic HTML.
Routing: A sophisticated routing system that maps incoming requests to specific actions in controllers.
Model Binding: Automatically maps incoming request data (form values, query string parameters, etc.) to action method parameters.
Data Validation: Built-in support for data annotations and custom validation logic.
Tag Helpers: Server-side HTML tag helpers that enable you to write cleaner, more declarative Razor code.
Dependency Injection: First-class support for dependency injection, making your code more modular and testable.
Cross-Platform: Runs on Windows, macOS, and Linux.
High Performance: Optimized for speed and efficiency.

Getting Started

To create an ASP.NET Core MVC application, you can use the .NET CLI:

dotnet new mvc -o MyMvcApp
cd MyMvcApp
dotnet run

This will create a new MVC project and start a development server. You can then access your application at the provided URL (usually https://localhost:5001 or http://localhost:5000).

Core Components Explained

Controllers

Controllers are C# classes that inherit from Microsoft.AspNetCore.Mvc.Controller. They contain action methods that handle incoming requests.

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();
    }

    public IActionResult Contact()
    {
        ViewData["Message"] = "Your contact page.";
        return View();
    }
}

Views

Views are typically implemented using Razor syntax (.cshtml files). They render the HTML that is sent to the client.

@model YourApp.Models.HomeViewModel

@{
    ViewData["Title"] = "Home Page";
}


    Welcome to ASP.NET Core MVC!
    @Model.Message
    Learn more »

Models

Models represent the data structure and business logic. They can be simple POCOs (Plain Old C# Objects).

namespace YourApp.Models
{
    public class HomeViewModel
    {
        public string Message { get; set; }
    }
}

Commonly Used APIs

`Controller`

Base class for controllers. Provides access to properties like Request, Response, ViewData, and methods for returning results.

Key methods: View(), RedirectToAction(), NotFound(), Ok().

`IActionResult`

Represents an action result that can be executed by the action method, typically by returning an instance of a class that implements this interface.

Common implementations: ViewResult, RedirectResult, StatusCodeResult, JsonResult.

`ViewDataDictionary`

A dictionary that allows you to pass data from the controller to the view. It's a simple key-value store.

`ModelStateDictionary`

Stores model state, including validation errors and bound values.

Microsoft Docs