Crystal E-Commerce (Kemal)

A lightweight e-commerce backend built with Crystal, Kemal and SQLite.

This project started from the e-commerce example available in the Kemal by Example repository and has been significantly extended to provide a richer backend suitable for framework migration benchmarks and architecture evaluation.

The goal of this repository is to serve as a realistic backend application for evaluating framework migrations (e.g. Kemal → Lucky) while preserving application behavior and business rules.

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Original Reference

This project was originally based on:

https://github.com/sdogruyol/kemal-by-example

Specifically, the ecommerce example.

The original implementation has been extensively modified and expanded.

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Technology Stack

• Crystal
• Kemal
• SQLite
• crystal-db
• kemal-session

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Features

Authentication

• User registration
• Login
• Session-based authentication
• Logout

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Authorization

• User roles
• Administrator access (is_admin)
• Protected administrative routes

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Product Management

• Product catalog
• Product inventory
• Product availability validation
• Product creation (Admin only)
• Product updates (Admin only)
• Product deletion (Admin only)

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Categories

• Category model
• Product categorization
• Category filtering
• Category listing

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Shopping Cart

• Add products
• Remove products
• Quantity updates
• Cart persistence

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Orders

• Checkout flow
• Order history
• Order items

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Search

• Product search
• Category filtering
• Search combined with filters

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Pagination

• Product pagination
• Public product listings show 8 products per page
• Admin product listings show 10 products per page

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Project Structure

src/
│
├── config/
├── helpers/
├── models/
├── routes/
└── views/

db/

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Database

SQLite

Current entities:

• Users
• Products
• Categories
• CartItems
• Orders
• OrderItems

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Business Rules

• Authentication required for shopping features.
• Only administrators can create, update, and delete products.
• Products belong to a category.
• Orders preserve purchased item information.
• Product searches support category filtering.
• Pagination is applied to product listings.

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Running

Install dependencies:

shards install

Run:

crystal run src/ecommerce.cr

Open:

http://127.0.0.1:5000

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Purpose

This repository is intended for:

• Framework migration evaluation
• Crystal ecosystem experimentation
• Backend architecture comparison
• AI coding model benchmarking

It intentionally contains multiple interacting backend features to create a migration task that requires understanding of routing, persistence, business rules, authentication and project organization rather than simple code translation.

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License

This project is derived from the MIT licensed example available in the Kemal by Example repository.

Additional modifications and new features were implemented independently.