Creating ASP.NET Core Applications

ASP.NET Core is a cross-platform, high-performance, open-source framework for building modern, cloud-enabled applications. This document provides a detailed overview of how to create and structure your ASP.NET Core projects.

Getting Started with ASP.NET Core

The primary tools for developing ASP.NET Core applications are:

• .NET SDK: Essential for building, running, and publishing .NET applications.
• Integrated Development Environment (IDE): Visual Studio (Windows) or Visual Studio Code (cross-platform) are highly recommended.

Creating a New Project

You can create a new ASP.NET Core project using the .NET CLI or your preferred IDE.

Using the .NET CLI

Open your terminal or command prompt and use the dotnet new command:

dotnet new webapp -o MyAspNetCoreApp
cd MyAspNetCoreApp
dotnet run
            

This command creates a new web application project named MyAspNetCoreApp. The webapp template is a good starting point for most web applications, including Razor Pages.

Using Visual Studio

1. Launch Visual Studio.
2. Select "Create a new project".
3. Search for "ASP.NET Core Web App" and select the appropriate template.
4. Configure your project name and location.
5. Choose your desired .NET version and framework (e.g., .NET 6.0, .NET 7.0, .NET 8.0).
6. Click "Create".

Project Structure

A typical ASP.NET Core project has a well-defined structure:

• Pages/ (for Razor Pages) or Controllers/ and Views/ (for MVC)
• wwwroot/: Static files (CSS, JavaScript, images).
• appsettings.json: Application configuration.
• Program.cs: Application entry point and host configuration.
• Startup.cs (in older .NET Core versions): Middleware configuration and service registration.

The Program.cs file is the heart of your application's setup in modern ASP.NET Core versions. It defines the web host builder, configures services, and sets up the request pipeline.

// Program.cs
var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddRazorPages(); // Or builder.Services.AddControllersWithViews();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthorization();

app.MapRazorPages(); // Or app.MapControllerRoute(...)

app.Run();
            

Common Project Templates

ASP.NET Core provides several templates to accelerate development:

Configuration and Dependency Injection

ASP.NET Core has built-in support for configuration and dependency injection (DI). Services are registered in Program.cs (or Startup.cs) and can be injected into controllers, Razor Pages, and other components.

public interface IMyService { string GetMessage(); }
public class MyService : IMyService { public string GetMessage() => "Hello from MyService!"; }
                

// In Program.cs:
builder.Services.AddSingleton<IMyService, MyService>();

// In a Razor Page or Controller:
public class IndexModel : PageModel
{
    private readonly IMyService _myService;

    public IndexModel(IMyService myService)
    {
        _myService = myService;
    }

    public string Message { get; private set; }

    public void OnGet()
    {
        Message = _myService.GetMessage();
    }
}
                

Best Practices

• Use the right template: Choose the template that best fits your application's requirements.
• Embrace Dependency Injection: Design your components to be loosely coupled and leverage DI for testability and maintainability.
• Separate concerns: Use MVC patterns or Razor Pages conventions to keep your code organized.
• Secure your application: Implement appropriate authentication and authorization mechanisms.
• Optimize for performance: Leverage caching, efficient data access, and other performance-tuning techniques.

By following these guidelines, you can build robust, scalable, and maintainable web applications with ASP.NET Core.