Track E – Tutorial 1: ASP.NET Core Fundamentals

Overview

ASP.NET Core is Microsoft's cross‑platform framework for building modern cloud‑based applications. This tutorial covers the essentials: project setup, building REST APIs with controllers, Entity Framework Core for data access, and dependency injection.

Why this matters: ASP.NET Core is a first‑class framework for building high‑performance, secure, and scalable APIs. It's widely used in enterprise and cloud environments.

1. Project Setup

Use the .NET CLI to create a project:

                        dotnet new webapi -n MyApi
                        cd MyApi
                        dotnet run
                    

Project structure:

Controllers/ – API controllers
Models/ – entity models
Data/ – DbContext and repositories
Program.cs – application entry point
appsettings.json – configuration

2. Controllers & Routing

Use [ApiController] and [Route] attributes.

                        // Controllers/ProductsController.cs
                        [ApiController]
                        [Route("api/[controller]")]
                        public class ProductsController : ControllerBase {
                        [HttpGet]
                        public IActionResult GetAll() {
                        return Ok(new[] { new { Id = 1, Name = "Laptop" } });
                        }

                        [HttpGet("{id}")]
                        public IActionResult GetById(int id) {
                        return Ok(new { Id = id, Name = "Laptop" });
                        }

                        [HttpPost]
                        public IActionResult Create([FromBody] Product product) {
                        return CreatedAtAction(nameof(GetById), new { id = product.Id }, product);
                        }
                        }
                    

Attributes: [HttpGet], [HttpPost], [HttpPut], [HttpDelete], [FromBody], [FromQuery].

3. Entity Framework Core

EF Core is the ORM for .NET. Use code‑first approach.

                        dotnet add package Microsoft.EntityFrameworkCore.SqlServer
                        dotnet add package Microsoft.EntityFrameworkCore.Tools
                    

                        // Models/Product.cs
                        public class Product {
                        public int Id { get; set; }
                        public string Name { get; set; }
                        public decimal Price { get; set; }
                        }

                        // Data/AppDbContext.cs
                        public class AppDbContext : DbContext {
                        public AppDbContext(DbContextOptions options) : base(options) { }
                            public DbSet Products { get; set; }
                                }
                    

                        // Program.cs – register DbContext
                        builder.Services.AddDbContext(options =>
                            options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));
                    

Migrations

                        dotnet ef migrations add InitialCreate
                        dotnet ef database update
                    

4. Dependency Injection

ASP.NET Core has built‑in DI. Register services in Program.cs.

                        // Register a service
                        builder.Services.AddScoped();

                            // Use in controller
                            public class ProductsController : ControllerBase {
                            private readonly IProductService _productService;

                            public ProductsController(IProductService productService) {
                            _productService = productService;
                            }
                            }
                    

Service lifetimes: AddTransient, AddScoped, AddSingleton.

Quiz

Question 1

Which attribute marks a controller for API endpoints?

[Controller]
[ApiController]
[Route]
[WebApi]

Show answer

B. [ApiController].

Question 2

Which command creates a new database migration in EF Core?

dotnet ef migration add
dotnet ef migrations add
dotnet ef update
dotnet ef db

Show answer

B. dotnet ef migrations add.

Question 3

What is the default lifetime of a service registered with AddScoped?

Singleton
Transient
Scoped (per request)
Per method

Show answer

C. Scoped (per request).

Exercises

Exercise 1

Create a Category model with Id, Name, Description. Add a DbSet to the DbContext.

Sample answer

                                    public class Category {
                                    public int Id { get; set; }
                                    public string Name { get; set; }
                                    public string Description { get; set; }
                                    }
                                    // In AppDbContext: public DbSet Categories { get; set; }
                                

Exercise 2

Add a PUT /api/products/{id} endpoint that updates an existing product.

Sample answer

                                    [HttpPut("{id}")]
                                    public IActionResult Update(int id, [FromBody] Product product) {
                                    if (id != product.Id) return BadRequest();
                                    // Update logic
                                    return NoContent();
                                    }
                                

Homework

Homework 1

Build a complete CRUD API for Order with fields: Id, CustomerName, OrderDate, TotalAmount. Use EF Core and a service layer.

Sample outline

Model: Order (Id, CustomerName, OrderDate, TotalAmount)
DbContext: Orders DbSet
Service: IOrderService with CRUD methods
Controller: OrdersController with all endpoints
Migrations: Add and update database

Mini‑Project

Inventory Management API

Build an Inventory Management API with:

Product: Id, Name, SKU, Price, Stock
Category: Id, Name
Relationship: Product belongs to Category
CRUD for both
Search endpoint: GET /api/products?search=...&category=...

Sample outline

Models: Product, Category
DbContext: Configure relationships using Fluent API or attributes
Services: ProductService with search functionality
Controllers: ProductController, CategoryController
Migrations: Add and apply

Tutorial Summary

You learned the fundamentals of ASP.NET Core: project setup, building REST APIs with controllers, Entity Framework Core for data persistence, and dependency injection. You built a solid foundation for enterprise .NET development.

Key takeaway: ASP.NET Core is a modern, high‑performance framework with excellent tooling. Its dependency injection and ORM make it a joy to build maintainable applications.