Linters

OWOX Data Marts uses distributed lint-staged configurations following official best practices for multi-package monorepos.

🔄 Workflow Diagram

sequenceDiagram
    participant Dev as Developer
    participant Git as Git Hook
    participant LS as lint-staged
    participant Config as .lintstagedrc.json
    participant ESL as ESLint
    participant Prettier as Prettier

    Dev->>Git: git commit -m "..."
    Git->>LS: Trigger pre-commit hook
    LS->>LS: Detect staged files

    Note over LS,Config: Automatic config discovery
    LS->>Config: Find nearest .lintstagedrc.json
    Config-->>LS: Return configuration rules

    LS->>ESL: Run ESLint validation
    ESL-->>LS: Return results

    alt ESLint has errors
        LS->>Dev: ❌ Commit blocked
        Note right of Dev: Fix errors manually
        Dev->>Dev: git add fixes
        Dev->>Git: git commit (retry)
    else ESLint passes
        LS->>Prettier: Format files
        Prettier-->>LS: Files formatted
        LS->>Git: ✅ Continue commit
        Git->>Dev: 🎉 Commit successful
    end

🏗️ Architecture

Configuration Discovery

lint-staged automatically finds the nearest configuration file to each staged file:

📁 project-root/
├── .lintstagedrc.json          # Root config (fallback)
├── 📁 apps/
│   ├── 📁 backend/
│   │   ├── .lintstagedrc.json  # Backend-specific rules
│   │   └── src/app.module.ts   # → Uses backend config
│   └── 📁 web/
│       ├── .lintstagedrc.json  # Frontend-specific rules
│       └── src/App.tsx         # → Uses web config
└── 📁 packages/
    ├── 📁 ui/
    │   ├── .lintstagedrc.json  # UI-specific rules
    │   └── src/button.tsx      # → Uses UI config
    └── README.md               # → Uses root config

How It Works

1. File Detection: Git detects staged files
2. Config Discovery: lint-staged finds nearest .lintstagedrc.json for each file
3. Workspace Isolation: Each workspace runs with its own rules
4. Tool Execution: ESLint validates → Prettier formats (if validation passes)
5. Commit Control: Commit blocked if any errors found

📋 Configuration Examples

Backend TypeScript (apps/backend/.lintstagedrc.json)

{
  "*.{ts,tsx}": [
    "eslint --config ./eslint.config.mjs",
    "prettier --config ./prettier.config.mjs --write"
  ],
  "*.json": ["prettier --config ./prettier.config.mjs --write"],
  "*.md": ["prettier --config ./prettier.config.mjs --write"]
}

Frontend React (apps/web/.lintstagedrc.json)

{
  "*.{ts,tsx,js,jsx}": [
    "eslint --config ./eslint.config.js",
    "prettier --config ./prettier.config.js --write"
  ],
  "*.json": ["prettier --config ./prettier.config.js --write"],
  "*.{css,scss}": ["prettier --config ./prettier.config.js --write"]
}

Root Fallback (.lintstagedrc.json)

{
  "*.json": "prettier --write",
  "*.{yml,yaml}": "prettier --write"
}

🛠️ Setup

The setup is handled automatically by the tools/setup-husky.js script:

# Manual setup (if needed)
npm run setup:husky

# Automatic setup (runs on npm install)
npm install  # → triggers postinstall → setup:husky

What the setup does

1. Initializes Husky: Creates .husky/ directory
2. Creates pre-commit hook: Runs npm run pre-commit
3. Makes hook executable: Sets proper permissions

🚫 Bypassing Pre-commit Hooks

Sometimes you need to commit without running lint-staged:

Temporary Bypass (Single Commit)

# Emergency commit (skip all hooks)
git commit --no-verify -m "Emergency hotfix"

# Alternative short form
git commit -n -m "Emergency hotfix"

Temporary Disable (Multiple Commits)

# Disable pre-commit hook
mv .husky/pre-commit .husky/pre-commit.disabled

# Make your commits
git commit -m "WIP: Large refactoring"
git commit -m "WIP: Continue refactoring"

# Re-enable hook
mv .husky/pre-commit.disabled .husky/pre-commit

🐛 Troubleshooting

Common Issues

1. Hooks Not Running

# Check if hooks are executable
ls -la .husky/pre-commit

# Fix permissions (Unix/macOS)
chmod +x .husky/pre-commit

# Reinstall hooks
npm run setup:husky

2. ESLint Configuration Not Found

✖ ESLint couldn't find a configuration file.

# Solution: Ensure workspace has eslint.config.js/mjs
ls apps/backend/eslint.config.mjs
ls apps/web/eslint.config.js

3. Prettier Configuration Issues

✖ Prettier configuration not found

# Solution: Ensure workspace has prettier.config.js/mjs
ls apps/backend/prettier.config.mjs
ls apps/web/prettier.config.js

Debug Mode

# Run lint-staged with debug output
DEBUG=lint-staged* npm run pre-commit

# Check what files would be processed
npx lint-staged --dry-run

🎯 Best Practices

✅ Recommended Workflow

1. Write code with ESLint IDE integration
2. Stage changes: git add .
3. Commit: git commit -m "descriptive message"
4. If blocked: Fix errors and retry

✅ Fixing ESLint Errors

# See what's wrong
npm run lint

# Auto-fix simple issues
npm run lint:fix

# Format after fixing
npm run format

# Stage fixes and retry
git add . && git commit

❌ Anti-patterns

• Don’t blindly use --no-verify to skip hooks
• Don’t disable ESLint rules without team discussion
• Don’t commit with lint:fix without reviewing changes

📚 Adding New Workspaces

To add lint-staged to a new workspace:

1. Create configuration file:

   packages/new-package/.lintstagedrc.json

   {
     "*.{ts,tsx}": ["eslint --config ./eslint.config.js", "prettier --write"],
     "*.json": ["prettier --write"]
   }

2. Test the configuration:

   cd packages/new-package
   echo "test" > test.ts
   git add test.ts
   git commit -m "test"  # Should use new config automatically

3. No additional setup needed - lint-staged discovers configs automatically!

🔗 External Resources

• Official lint-staged documentation
• Monorepo best practices
• Husky documentation
• ESLint configuration
• Prettier configuration