ASP.NET Core Tutorial for Beginners | .NET 7

Introduction

This tutorial provides a step-by-step guide for beginners to build a complete REST API using ASP.NET Core and C#. By following this guide, you'll learn the essential concepts, tools, and best practices necessary for creating robust web applications with .NET 7.

Step 1: Set Up Your Development Environment

• Install Prerequisites

  • Ensure you have the following software installed:
    • .NET SDK
    • A code editor like Visual Studio or Visual Studio Code
    • Postman for testing your API

• Create a New Project

  • Open your terminal or command prompt.
  • Run the following command to create a new ASP.NET Core Web API project:

    dotnet new webapi -n YourApiName
    

  • Change directory into your project folder:

    cd YourApiName
    

Step 2: Understand Web API Essentials

• Learn Key Concepts
  • REST (Representational State Transfer) is an architectural style for designing networked applications.
  • Identify HTTP methods commonly used in REST APIs:
    • GET: Retrieve data
    • POST: Create new data
    • PUT: Update existing data
    • DELETE: Remove data

Step 3: Build Your API

• Add the Game Entity

  • Create a model class for your entity (e.g., Game):

    public class Game
    {
        public int Id { get; set; }
        public string Title { get; set; }
        public string Genre { get; set; }
    }
    

• Implementing Endpoints

  • GET ALL Endpoint

    • Create a method to retrieve all games:

      [HttpGet]
      public IEnumerable<Game> GetAllGames()
      {
          return _context.Games.ToList();
      }
      

  • GET BY ID Endpoint

    • Create a method to retrieve a game by ID:

      [HttpGet("{id}")]
      public ActionResult<Game> GetGameById(int id)
      {
          var game = _context.Games.Find(id);
          if (game == null) return NotFound();
          return game;
      }
      

  • POST Endpoint

    • Create a method to add a new game:

      [HttpPost]
      public ActionResult<Game> CreateGame(Game game)
      {
          _context.Games.Add(game);
          _context.SaveChanges();
          return CreatedAtAction(nameof(GetGameById), new { id = game.Id }, game);
      }
      

  • PUT Endpoint

    • Create a method to update a game:

      [HttpPut("{id}")]
      public IActionResult UpdateGame(int id, Game game)
      {
          if (id != game.Id) return BadRequest();
          
          _context.Entry(game).State = EntityState.Modified;
          _context.SaveChanges();
          return NoContent();
      }
      

  • DELETE Endpoint

    • Create a method to delete a game:

      [HttpDelete("{id}")]
      public IActionResult DeleteGame(int id)
      {
          var game = _context.Games.Find(id);
          if (game == null) return NotFound();
          _context.Games.Remove(game);
          _context.SaveChanges();
          return NoContent();
      }
      

Step 4: Organize Your Code and Validate Inputs

• Use Route Groups

  • Group related endpoints for better organization.

• Implement Server-Side Validation

  • Validate incoming data to ensure it meets your criteria before processing.

Step 5: Utilize Design Patterns and Best Practices

• Understand the Repository Pattern

  • Implement a repository to abstract data access logic.

• Use Dependency Injection

  • Leverage dependency injection to manage services and improve code testability.

Step 6: Configure SQL Server

• Set Up SQL Server with Docker

  • Run SQL Server as a Docker container:

    docker run -e "ACCEPT_EULA=Y" -e "SA_PASSWORD=Your_password123" -p 1433:1433 --name sqlserver -d mcr.microsoft.com/mssql/server
    

• Connect Your API to SQL Server

  • Store your connection string in appsettings.json:

    "ConnectionStrings": {
        "DefaultConnection": "Server=localhost;Database=YourDatabase;User Id=sa;Password=Your_password123;"
    }
    

Step 7: Use Entity Framework Core

• Set Up DBContext

  • Create a DbContext class to manage entity objects:

    public class ApplicationDbContext : DbContext
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options) { }
        public DbSet<Game> Games { get; set; }
    }
    

• Generate Migrations

  • Use the following command to create a migration:

    dotnet ef migrations add InitialCreate
    

  • Apply the migration:

    dotnet ef database update
    

Conclusion

This tutorial guides you through the foundational steps needed to create a REST API using ASP.NET Core and C#. You learned to set up your environment, implement CRUD operations, utilize design patterns, and configure your API with SQL Server.

For further learning, consider exploring advanced topics like authentication, authorization, and deploying your application. Happy coding!