Complete ASP.NET Core Tutorial: Beginner to Expert

1. Introduction to ASP.NET Core

ASP.NET Core is a cross-platform, high-performance framework for building modern web applications. It supports MVC, API development, microservices, authentication, and more.

Why Choose ASP.NET Core?

✅ Cross-platform (Windows, Linux, macOS)
✅ Open-source and high-performance
✅ Supports dependency injection and middleware
✅ Built-in security and authentication
✅ Seamless integration with databases and cloud services

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2. Setting Up the Development Environment

Install Required Tools

• Visual Studio 2022 (or Visual Studio Code)
• .NET SDK (latest version)
• SQL Server (for database)
• Postman or Swagger (for API testing)

Creating Your First ASP.NET Core Project

1. Open Visual Studio and select Create a new project.
2. Choose ASP.NET Core Web App (MVC or API).
3. Configure project name and click Create.
4. Run the project using dotnet run to check setup.

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3. Understanding the ASP.NET Core Architecture

Project Structure

• Controllers/ – Handles user requests.
• Models/ – Defines data structures.
• Views/ – UI (for MVC projects).
• wwwroot/ – Static files (CSS, JS, Images).
• appsettings.json – Configuration settings.
• Program.cs – Configures the application.

Middleware and Dependency Injection

Middleware processes requests and responses. Example:

app.Use(async (context, next) => {
    Console.WriteLine("Middleware before request");
    await next();
    Console.WriteLine("Middleware after response");
});

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4. Building a Web Application with MVC

Creating a Controller

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

Creating a View (Index.cshtml)

<h1>Welcome to ASP.NET Core</h1>

Routing in ASP.NET Core

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

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5. Working with Databases (Entity Framework Core & SQL Server)

Setting Up Database Connection

1. Install EF Core package:

   dotnet add package Microsoft.EntityFrameworkCore.SqlServer
   

2. Configure appsettings.json:

   "ConnectionStrings": {
       "DefaultConnection": "Server=your-server;Database=your-db;User Id=your-user;Password=your-password;"
   }
   

3. Add DbContext in Program.cs:

   builder.Services.AddDbContext<ApplicationDbContext>(options =>
       options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));
   

4. Create a model:

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

5. Create database migration:

   dotnet ef migrations add InitialCreate
   dotnet ef database update
   

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6. Building a REST API in ASP.NET Core

Creating an API Controller

[Route("api/[controller]")]
[ApiController]
public class ProductController : ControllerBase {
    private readonly ApplicationDbContext _context;

    public ProductController(ApplicationDbContext context) {
        _context = context;
    }

    [HttpGet]
    public async Task<ActionResult<IEnumerable<Product>>> GetProducts() {
        return await _context.Products.ToListAsync();
    }
}

Testing the API with Swagger

Enable Swagger in Program.cs:

builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

Run the project and visit /swagger.

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7. Authentication & Authorization

Adding Authentication Using OAuth/JWT

builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
    .AddJwtBearer(options => {
        options.Authority = "https://your-oauth-provider.com";
        options.Audience = "your-api-audience";
    });

Use [Authorize] to protect API endpoints:

[Authorize]
[HttpGet]
public IActionResult GetSecureData() {
    return Ok("This is a protected resource.");
}

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8. Advanced Topics

Microservices with ASP.NET Core

• Use Docker to containerize ASP.NET Core apps.
• Implement gRPC or RESTful APIs for communication.
• Use RabbitMQ/Kafka for event-driven architecture.

Performance Optimization

• Enable Response Caching:

  builder.Services.AddResponseCaching();
  app.UseResponseCaching();
  

• Use Compression to reduce payload size:

  builder.Services.AddResponseCompression();
  

Deployment to Cloud (Azure/AWS)

• Azure App Service: Publish from Visual Studio.
• Docker & Kubernetes: Deploy microservices.
• CI/CD Pipelines: Use GitHub Actions or Azure DevOps.

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9. Conclusion

By following this tutorial, you have learned: ✅ How to build a web app using ASP.NET Core & MVC.
✅ How to integrate SQL Server with Entity Framework Core.
✅ How to build REST APIs with authentication and security.
✅ How to optimize, deploy, and scale your ASP.NET Core applications.

Now, start building your own ASP.NET Core projects!