Beginner LevelREST APIs & Web Services
Why is strict Request Payload Schema Validation essential for REST APIs?
❓ Interview Prompt: Explain input validation, Zod / JSON Schema validation middleware, sanitizing inputs, preventing SQL injection & XSS, and `400 Bad Request` responses.
Unvalidated request payloads are the #1 attack vector for security exploits (SQL injection, XSS, Buffer Overflow, Mass Assignment):
Best Practice:
Validate request bodies, path parameters, and query params at the API gateway or middleware entry layer using strict schemas (e.g. Zod, Joi, Ajv). Reject invalid payloads instantly with '400 Bad Request' before reaching controller logic!
Code Implementation Example
typescript
import { z } from 'zod';
import { Request, Response, NextFunction } from 'express';
const CreateUserSchema = z.object({
email: z.string().email(),
age: z.number().min(18).max(120)
});
export const validateBody = (schema: z.ZodSchema) => (req: Request, res: Response, next: NextFunction) => {
const result = schema.safeParse(req.body);
if (!result.success) return res.status(400).json({ errors: result.error.errors });
req.body = result.data;
next();
};💡Zod schema validation middleware rejecting invalid payloads with 400 Bad Request.
🎯 Interview Key Takeaway
Validate incoming request payloads strictly using schemas like Zod at the API entry point to prevent security vulnerabilities.
#Validation#Zod#Security#Beginner
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