Data Layer

Goal

This snapshot advances Emberquay 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 Elixir 1.15+, Mix, Node.js 20+, and Docker for Postgres stages.

Port 4002 must be free. Copy .env.example before database stages.

• Elixir and Mix
• Node.js and npm
• Docker from part 4 onward

Concepts

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

LiveView keeps interactive UI on the server; Tailwind styles the storefront; Ecto 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.

schema "products" do
  belongs_to :user, User
  belongs_to :category, Category
  field :name, :string
  field :slug, :string
  field :price_cents, :integer
  field :stock, :integer, default: 0
end

Run and verify

Enter 04-Data-Layer, mix deps.get, copy .env.example, migrate, seed, and start Phoenix on port 4002.

Open http://127.0.0.1:4002. From data lessons onward, Ada and Grace use password123.

docker compose up -d
git clone https://github.com/michaeldunga1/fcc-phoenix-ecommerce.git
cd fcc-phoenix-ecommerce/04-Data-Layer
mix deps.get
npm --prefix assets install
cp .env.example .env
mix ecto.setup
mix phx.server

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 ember_NN name. Never commit .env, _build, deps, 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