Microsoft.AspNetCore.Mvc

Namespace for ASP.NET Core MVC components, enabling the creation of powerful, data-driven applications using the Model-View-Controller pattern.

Core Concepts

The Microsoft.AspNetCore.Mvc namespace provides the building blocks for developing web applications with ASP.NET Core that follow the MVC architectural pattern. This includes controllers, actions, views, models, routing, and model binding.

Controllers

Controllers are responsible for handling incoming HTTP requests, processing them, and returning responses. They act as the entry point for your application's logic.

Key features of controllers include:

• Action Methods: Public methods within a controller that are invoked in response to specific HTTP requests.
• Model Binding: Automatically maps incoming request data (query strings, form data, route data) to action method parameters.
• View Rendering: Facilitates rendering views (HTML, JSON, etc.) to be sent back to the client.

Actions

Action methods are the specific functions within a controller that handle a particular request. They are typically public methods that return an IActionResult.

Common IActionResult implementations include:

• OkResult: Returns an HTTP 200 OK status.
• NotFoundResult: Returns an HTTP 404 Not Found status.
• JsonResult: Returns JSON data.
• ViewResult: Renders a view.

Views

Views are responsible for presenting data to the user, typically as HTML. They are often created using Razor syntax (.cshtml files).

Model Binding and Validation

ASP.NET Core MVC automatically binds incoming request data to your controller action parameters. You can also apply validation attributes to your models to ensure data integrity.

Routing

The routing system maps incoming URL requests to specific action methods in your controllers. Convention-based routing and attribute routing are supported.

Key Classes and Interfaces

• ControllerBase: A base class for controllers that does not include view support, ideal for API controllers.
• IController: Interface implemented by all controllers.
• ActionContext: Provides context for action execution.
• ModelStateDictionary: Manages the state of model binding and validation.

Example: A Simple API Controller

Here's a basic example of an API controller that returns a list of items:

using Microsoft.AspNetCore.Mvc;
using System.Collections.Generic;

[ApiController]
[Route("api/[controller]")]
public class ProductsController : ControllerBase
{
    [HttpGet]
    public ActionResult<IEnumerable<string>> Get()
    {
        var products = new List<string> { "Laptop", "Keyboard", "Mouse" };
        return Ok(products);
    }

    [HttpGet("{id}")]
    public ActionResult<string> Get(int id)
    {
        if (id == 1)
        {
            return Ok("Laptop");
        }
        return NotFound();
    }
}