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Data Layer

Persist authors and posts with Lucid and PostgreSQL.

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

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