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Exercise 1: Minimal API Basics

Objective​

Build a simple Minimal API for managing a product catalog.

Requirements​

  1. Create a new ASP.NET Core Web API project
  2. Implement CRUD endpoints using Minimal APIs
  3. Use in-memory storage (List<Product>)
  4. Return appropriate HTTP status codes

Steps​

1. Create Project​

dotnet new web -n MinimalApiBasics
cd MinimalApiBasics

2. Create Product Model​

public record Product(int Id, string Name, decimal Price);

3. Implement Endpoints​

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

// In-memory storage
var products = new List<Product>();
var nextId = 1;

// GET all products
app.MapGet("/api/products", () => Results.Ok(products));

// GET product by ID
app.MapGet("/api/products/{id:int}", (int id) =>
{
    var product = products.FirstOrDefault(p => p.Id == id);
    return product is null ? Results.NotFound() : Results.Ok(product);
});

// POST create product
app.MapPost("/api/products", (Product product) =>
{
    var newProduct = product with { Id = nextId++ };
    products.Add(newProduct);
    return Results.Created($"/api/products/{newProduct.Id}", newProduct);
});

// PUT update product
app.MapPut("/api/products/{id:int}", (int id, Product updated) =>
{
    var index = products.FindIndex(p => p.Id == id);
    if (index == -1) return Results.NotFound();

    products[index] = updated with { Id = id };
    return Results.Ok(products[index]);
});

// DELETE product
app.MapDelete("/api/products/{id:int}", (int id) =>
{
    var removed = products.RemoveAll(p => p.Id == id);
    return removed > 0 ? Results.NoContent() : Results.NotFound();
});

app.Run();

4. Test with curl​

# Create products
curl -X POST http://localhost:5000/api/products \
  -H "Content-Type: application/json" \
  -d '{"name":"Laptop","price":999.99}'

# Get all
curl http://localhost:5000/api/products

# Get by ID
curl http://localhost:5000/api/products/1

# Update
curl -X PUT http://localhost:5000/api/products/1 \
  -H "Content-Type: application/json" \
  -d '{"name":"Gaming Laptop","price":1299.99}'

# Delete
curl -X DELETE http://localhost:5000/api/products/1

Challenge​

  1. Add input validation
  2. Implement search/filter by name
  3. Add pagination support
  4. Group endpoints using MapGroup

Expected Outcome​

  • Working CRUD API with Minimal APIs
  • Proper HTTP status codes (200, 201, 204, 404)
  • Clean, readable code