.NET Core Web API

Introduction

.NET Core Web API is a framework for building scalable and high-performance RESTful services using .NET Core. It provides powerful features such as dependency injection, middleware pipeline, and built-in support for authentication and authorization.

Setting Up a .NET Core Web API Project

To create a new .NET Core Web API project, use the following command:

 dotnet new webapi -n MyApi

Navigate to the project folder:

 cd MyApi

Run the application:

 dotnet run

Folder Structure

A typical .NET Core Web API project follows this structure:

MyApi/
│-- Controllers/
│   ├── WeatherForecastController.cs
│-- Models/
│-- Services/
│-- Program.cs
│-- appsettings.json

Creating a Controller

Controllers handle incoming HTTP requests and return responses. Example:

[ApiController]
[Route("api/[controller]")]
public class ProductsController : ControllerBase
{
    [HttpGet]
    public IActionResult Get()
    {
        return Ok(new { message = "Hello from API" });
    }
}

Dependency Injection

.NET Core has built-in dependency injection. Register services in Program.cs:

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddScoped<IMyService, MyService>();

Inject into controllers:

public class MyController : ControllerBase
{
    private readonly IMyService _service;
    public MyController(IMyService service)
    {
        _service = service;
    }
}

Middleware Pipeline

Middleware are components that handle requests and responses. Configure in Program.cs:

var app = builder.Build();
app.UseRouting();
app.UseAuthorization();
app.MapControllers();
app.Run();

Authentication & Authorization

To add JWT authentication:

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

Apply [Authorize] to controllers:

[Authorize]
public class SecureController : ControllerBase
{
    [HttpGet]
    public IActionResult GetSecureData()
    {
        return Ok("This is a secured endpoint");
    }
}

Configuring Swagger

Add Swagger for API documentation:

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

Enable it in Program.cs:

app.UseSwagger();
app.UseSwaggerUI();

Run the application and access https://localhost:<port>/swagger.

Conclusion

.NET Core Web API is a powerful framework for building RESTful services. It provides built-in support for dependency injection, middleware, authentication, and more. By following best practices, you can build scalable and maintainable APIs efficiently.

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Happy coding! 🚀