sonht1109/backend-development

Core Conventions

These conventions apply to ALL backend code. They override your defaults because they represent this project's standards, not general best practices.

JSON Response Format

All JSON response keys MUST use snake_case. This is a deliberate project convention — Claude's default is camelCase, which is wrong for this project.

// Correct (this project's convention)
{ "user_id": 1, "first_name": "John", "created_at": "2024-01-01" }

// Wrong (Claude's default)
{ "userId": 1, "firstName": "John", "createdAt": "2024-01-01" }

Structured Logging

Use a structured logger (e.g. logger.info(), logger.error(), logger.warn()), never console.log or console.error. Structured logs with metadata are essential for observability in production.

// Correct
logger.error('Order creation failed', {
  error: error.message,
  user_id: userId,
  product_id: productId,
});

// Wrong
console.error('Order creation failed:', error);
console.log(error);

Input Validation

Use schema validation libraries (zod, Joi, or class-validator) instead of writing manual validation functions. Schema libraries provide consistent error formats, type coercion, and are easier to maintain.

// Correct — use zod
const createOrderSchema = z.object({
  user_id: z.number().int().positive(),
  product_id: z.number().int().positive(),
  quantity: z.number().int().positive().max(1000),
});

// Wrong — manual validation
if (!userId || typeof userId !== 'number') { ... }

References

Read the relevant reference when working in that domain:

• backend-database: query optimization, transactions.
• backend-security: injection prevention, cryptography, logging security, input validation.
• backend-code-quality: naming, SRP, error handling, constants.