Login and Session Cart

Goal

This snapshot advances Emberquay Market by teaching you to authenticate users and keep a session shopping cart.

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

Session auth restores the user; the cart lives in session as product id to quantity until checkout.

LiveView keeps interactive UI on the server; Tailwind styles the storefront; Ecto owns persistence and authorization checks.

Walkthrough

Add login/logout and an Add to Cart action that updates session state.

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

cart = get_session(socket, :cart) || %{}
put_session(socket, :cart, Map.update(cart, id, 1, &(&1 + 1)))

Run and verify

Enter 07-Login-And-Cart, 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/07-Login-And-Cart
mix deps.get
npm --prefix assets install
cp .env.example .env
mix ecto.setup
mix phx.server

Troubleshooting

A changed session secret invalidates sessions; clear cookies and try again.

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

Log in as Ada, add two items, refresh, and confirm the cart badge persists.

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