Retail Monolith App

A lightweight ASP.NET Core 9 Razor Pages application that simulates a retail monolith before decomposition.
It includes product listing, shopping cart, checkout, and inventory management — built to demonstrate modernisation and refactoring patterns.

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Features

• ASP.NET Core 9 (Razor Pages)
• Entity Framework Core (SQL Server LocalDB)
• Dependency Injection with modular services:
  • CartService
  • CheckoutService
  • MockPaymentGateway
• 50 sample seeded products with random inventory
• End-to-end retail flow:
  • Products → Cart → Checkout → Orders
• Minimal APIs:
  • POST /api/checkout
  • GET /api/orders/{id}
• Health-check endpoint at /health
• Ready for decomposition into microservices

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🏠 Home Page

🛍 Products

🧺 Cart

💳 Checkout

📦 Orders

📦 Order Details

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Development Setup

You can run and edit this application in three different ways:

1. Local Development Environment

Run the application directly on your local machine with your preferred IDE or editor.

Prerequisites:

• .NET 9 SDK installed (download)
• SQL Server LocalDB (included with Visual Studio) or SQL Server instance
• Your favorite code editor (Visual Studio, VS Code, Rider, etc.)

Steps:

git clone https://github.com/lavann/ads_monotlith_app.git
cd ads_monotlith_app
dotnet restore
dotnet ef database update
dotnet run

2. Docker-Hosted Dev Container

Use a Docker container with a pre-configured development environment. This ensures consistency across different machines without installing dependencies locally.

Prerequisites:

• Docker Desktop installed and running
• Visual Studio Code with the Dev Containers extension

Steps:

1. Clone the repository
2. Open the folder in VS Code
3. When prompted, click "Reopen in Container" (or use Command Palette: Dev Containers: Reopen in Container)
4. VS Code will build and start the dev container with all dependencies pre-installed
5. Run dotnet ef database update and dotnet run inside the container terminal

3. GitHub Codespaces

Develop entirely in the cloud with zero local setup. Codespaces provides a full VS Code environment in your browser.

Prerequisites:

• GitHub account with Codespaces access

Steps:

1. Navigate to the repository on GitHub
2. Click the green "Code" button
3. Select the "Codespaces" tab
4. Click "Create codespace on main"
5. Wait for the environment to initialize
6. Run dotnet ef database update and dotnet run in the integrated terminal

All three environments provide the same development experience with the .NET SDK, C# extension, and all necessary tools pre-configured.

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Database & Migrations

Apply existing migrations

dotnet ef database update

Create a new migration

• If you modify models:

  • dotnet ef migrations add <MigrationName>
  • dotnet ef database update

• EF Core uses DesignTimeDbContextFactory (Data/DesignTimeDbContextFactory.cs) with the connection string:

  • Server=(localdb)\MSSQLLocalDB;Database=RetailMonolith;Trusted_Connection=True;MultipleActiveResultSets=true

Seeding Sample Data

At startup, the app automatically runs await AppDbContext.SeedAsync(db); which seeds 50 sample products with random categories, prices, and inventory.

To reseed manually:

dotnet ef database drop -f
dotnet ef database update
dotnet run

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Running the Application

Start the application:

dotnet run

Access the app at https://localhost:5001 or http://localhost:5000.

Available Endpoints

Path	Description
/	Home Page
/Products	Product catalogue
/Cart	Shopping cart
/api/checkout	Checkout API
/api/orders/{id}	Order details API
/health	Health check endpoint

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Environment Variables (optional)

You can override the default connection string by setting the ConnectionStrings__DefaultConnection environment variable.

Variable	Description	Default
ConnectionStrings__DefaultConnection	Database connection string	LocalDB instance
ASPNETCORE_ENVIRONMENT	Environment mode	Development