---

name: api-implementer description: Implements API endpoints, routes, controllers, and request/response handling. Use when implementing REST APIs, GraphQL APIs, or other API endpoints. Handles routing, validation, error handling, and response formatting.

API Implementer Skill

Instructions

1. Analyze API requirements from task
2. Review API specifications (endpoints, request/response formats)
3. Implement API endpoints with proper routing
4. Add request validation
5. Implement error handling
6. Format responses correctly
7. Return implementation with:
   • Route definitions
   • Controller/handler functions
   • Validation logic
   • Error handling
   • Response formatting

Examples

Input: "Implement POST /api/tasks endpoint" Output:

Copy// routes/tasks.js
router.post('/api/tasks', authenticate, validateTaskInput, async (req, res) => {
    try {
        const task = await createTask({
            title: req.body.title,
            description: req.body.description,
            userId: req.user.id
        });
        res.status(201).json(task);
    } catch (error) {
        res.status(400).json({ error: error.message });
    }
});

// middleware/validation.js
function validateTaskInput(req, res, next) {
    if (!req.body.title || req.body.title.trim().length === 0) {
        return res.status(400).json({ error: 'Title is required' });
    }
    if (req.body.title.length > 255) {
        return res.status(400).json({ error: 'Title must be 255 characters or less' });
    }
    next();
}

API Implementation Areas

• Route Definition: HTTP method, path, middleware
• Request Handling: Parse request body, query params, headers
• Validation: Input validation, data sanitization
• Business Logic: Core functionality implementation
• Error Handling: Proper error responses, status codes
• Response Formatting: Consistent response structure
• Authentication: Auth middleware, token validation
• Authorization: Permission checks, role-based access

Best Practices

• RESTful Design: Follow REST conventions
• Consistent Responses: Standard response format
• Proper Status Codes: Use appropriate HTTP status codes
• Error Handling: Comprehensive error handling
• Validation: Validate all inputs
• Documentation: Document endpoints and parameters