Shopping Basket API

This is a REST API implementing an online shopping basket system using .NET 8 and C# 12. The focus is on clean architecture, domain-driven design principles, and REST API best practices. The basket and its items are stored in-memory for simplicity.

Features Implemented

Basket Management

• Add an item to the basket
• Add multiple items to the basket
• Remove an item from the basket
• Add multiple of the same item to the basket (increases quantity)
• Retrieve the basket
• Clear the basket
• Ensure all items in the basket have the same currency

Pricing

• Get the total cost of the basket with VAT (20%)
• Get the total cost of the basket without VAT

Discounts

• Add discounted items (per-item discount)
• Apply discount codes to the basket (excluding already discounted items)

Shipping

• Apply shipping cost based on country (UK, US, DE, or default cost)

Validation

• Request validation using FluentValidation
• Business rules are also validated, for example positive price and quantity greater than or equal to 1.

Error handling

• Global exception handling middleware
• Returns 400 responses for validation errors

Logging

• Integrated request/response logging middleware
• Application level logging for critical operations

Documentation

• Swagger/OpenAPI with grouped endpoints
• Explicit response types

Tests

• There are some unit tests for the Domain and Application layers.

How to run the API

1. Restore dependencies:

dotnet restore

2. Build the solution

dotnet build

3. Run the API:

dotnet run --project src/Basket.Api/ShoppingBasket.Api.csproj

4. Open the browser, and navigate to http://localhost:5132/index.html to access the Swagger page. You can find the port in the console:

Now listening on: http://localhost:5132

How to run the unit tests

dotnet test

Next steps and improvements

• Add support to multiple baskets
• Add authentication/authoriaztion
• Replace in-memory repository with a database
• Add persistence with migrations
• Remove hard-coded discount codes and replace them with codes from the database
• Remove the hard-coded list of countries and their shipping costs and replace them with data from the database
• Support multiple currencies with proper conversion rules
• Improve test coverage with integration tests for API layer
• Add metrics/telemetry
• Add API rate limits
• Provide Dockerfile for containerized deployment
• Consider using CQRS