Data Layer

Goal

This snapshot advances Canopy Journal by teaching you to persist authors and posts with Lucid and PostgreSQL.

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

Prerequisites

Use Node.js 20+, npm, and Docker for Postgres stages. You should recognize async functions and HTTP verbs.

Port 3002 must be free. Copy .env.example before starting database stages.

• Node.js and npm
• A code editor and terminal
• Docker from part 4 onward

Concepts

Lucid models map tables. Each snapshot uses its own canopy database.

Keep controllers thin: routes accept input, Lucid models enforce rules, and Edge escapes output by default.

Walkthrough

Connect DATABASE_URL, create User and Post models, seed Ada and Grace.

Read the example, then open the matching snapshot. The repository includes the surrounding setup and error handling.

const posts = await Post.query().preload('author').orderBy('created_at', 'desc')

Run and verify

Enter 04-Data-Layer, install dependencies, copy .env.example when present, and start Ace on port 3002.

Open http://127.0.0.1:3002. Watch the terminal for validation and database errors.

docker compose up -d
git clone https://github.com/michaeldunga1/fcc-adonis-blog.git
cd fcc-adonis-blog/04-Data-Layer
npm install
cp .env.example .env
node ace serve --watch

Troubleshooting

Connection refused usually means Docker Postgres is stopped or the port is not 5440.

For database failures, confirm Docker and the canopy_NN name when applicable. Never commit .env or node_modules.

• Read the first error first
• Restart after environment changes
• Never commit secrets

Try this

Add a minimum title length check before insert.

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