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Data Layer

Model categories and products with migrations and seeds.

Goal

This snapshot advances Cobblecart Market by teaching you to model categories and products with migrations and seeds.

Every numbered folder is a complete app. Run this stage independently, then compare it with the previous folder.

Prerequisites

Use Ruby 3.2+, Bundler, Node.js 20+, and Docker for Postgres stages.

Port 3010 must be free. Copy .env.example before database stages.

  • Ruby and Bundler
  • Node.js and npm
  • Docker from part 4 onward

Concepts

Each snapshot uses an isolated cobble_NN database so stages stay independent.

Turbo keeps interactive UI on the server; Tailwind styles the storefront; Active Record owns persistence and authorization checks.

Walkthrough

Migrate Category and Product tables, relate them, and seed Ada, Grace, and a starter catalog.

Read the example, then open the matching snapshot. The repository includes validation, CSRF, and the surrounding structure.

create_table :products do |t|
  t.references :user, null: false, foreign_key: true
  t.references :category, null: false
  t.string :name, null: false
  t.string :slug, null: false
  t.integer :price_cents, null: false
  t.integer :stock, default: 0
end

Run and verify

Enter 04-Data-Layer, bundle install, copy .env.example, migrate, seed, and boot Puma on port 3010.

Open http://127.0.0.1:3010. From data lessons onward, Ada and Grace use password123.

docker compose up -d
git clone https://github.com/michaeldunga1/fcc-rails-ecommerce.git
cd fcc-rails-ecommerce/04-Data-Layer
bundle install
npm install
cp .env.example .env
bin/rails db:prepare
bin/rails server -b 0.0.0.0 -p 3010

Troubleshooting

Connection refused usually means Docker is down or the database name does not match this folder's index.

For database failures, confirm Docker and the cobble_NN name. Never commit .env, vendor/bundle, or node_modules.

  • Read the first exception first
  • Rebuild assets after Tailwind class changes
  • Never commit secrets

Try this

Add a nullable sku column through a new migration.

Test a happy path and one invalid or unauthorized request.

  • Make one small change
  • Test it in the browser
  • Compare with the next snapshot only after it works

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