Agent skill
pitfalls-express-api
Express API conventions and storage patterns. Use when building REST APIs, defining routes, or implementing storage interfaces. Triggers on: Express, router, API route, status code, storage interface.
Install this agent skill to your Project
npx add-skill https://github.com/aiskillstore/marketplace/tree/main/skills/barissozen/pitfalls-express-api
SKILL.md
Express API Pitfalls
Common pitfalls and correct patterns for Express APIs.
When to Use
- Building REST API routes
- Implementing storage interfaces
- Setting HTTP status codes
- Validating request bodies
- Reviewing Express API code
Workflow
Step 1: Verify Route Structure
Check that routes follow REST conventions.
Step 2: Check Status Codes
Ensure correct status codes for each operation.
Step 3: Verify Validation
Confirm input validation middleware is in place.
Route Structure
// Public routes
GET /api/resource // List
GET /api/resource/:id // Get one
// Admin routes (with auth middleware)
POST /api/admin/resource // Create (201)
PATCH /api/admin/resource/:id // Update (200)
DELETE /api/admin/resource/:id // Delete (204)
// ✅ Always validate before storage
router.post('/', validateBody(schema), async (req, res) => {
const validated = req.body; // Already validated by middleware
});
Status Codes
| Operation | Success | Not Found | Invalid |
|---|---|---|---|
| GET | 200 | 404 | 400 |
| POST | 201 | - | 400 |
| PATCH | 200 | 404 | 400 |
| DELETE | 204 | 404 | - |
Storage Interface Pattern
// ✅ Define interface for all storage operations
interface IStorage {
// Strategies
getStrategies(): Promise<Strategy[]>;
getStrategy(id: string): Promise<Strategy | undefined>;
createStrategy(data: NewStrategy): Promise<Strategy>;
updateStrategy(id: string, data: Partial<Strategy>): Promise<Strategy | undefined>;
deleteStrategy(id: string): Promise<boolean>;
}
// ✅ Implement for different backends
class DbStorage implements IStorage { ... } // PostgreSQL
class MemStorage implements IStorage { ... } // Testing
Background Job Patterns
// ✅ Cleanup on process exit
const intervals: NodeJS.Timeout[] = [];
function startJob(fn: () => void, ms: number) {
const id = setInterval(fn, ms);
intervals.push(id);
return id;
}
process.on('SIGTERM', () => {
intervals.forEach(clearInterval);
process.exit(0);
});
// ✅ Handle overlapping executions
let isRunning = false;
async function scanForOpportunities() {
if (isRunning) return;
isRunning = true;
try {
await scan();
} finally {
isRunning = false;
}
}
Quick Checklist
- Routes follow REST conventions
- Correct status codes returned
- Input validation on all endpoints
- Storage interface abstraction used
- Background jobs handle cleanup
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