Handling JSON Schema Validation Errors When Using Ajv with Express and TypeScript
I just started working with I'm currently working on a Node.js application using Express and TypeScript, and I'm implementing JSON Schema validation with the Ajv library. The question arises when I try to validate incoming requests against a schema for a user registration API. Despite following the Ajv documentation, I'm working with an unexpected behavior where valid data is being rejected with behavior messages indicating missing properties that are actually present. Here’s a sample of my schema: ```json { "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "username": { "type": "string" }, "email": { "type": "string", "format": "email" }, "password": { "type": "string", "minLength": 6 } }, "required": ["username", "email", "password"] } ``` And here’s the route handler where I perform the validation: ```typescript import { Request, Response } from 'express'; import Ajv from 'ajv'; const ajv = new Ajv(); const validate = ajv.compile(userSchema); app.post('/register', (req: Request, res: Response) => { const valid = validate(req.body); if (!valid) { return res.status(400).json({ errors: validate.errors }); } // proceed with registration logic }); ``` When I send a registration request like this: ```json { "username": "johndoe", "email": "john@example.com", "password": "secret123" } ``` The response I get is: ```json { "errors": [ { "keyword": "required", "dataPath": "", "schemaPath": "#/required", "params": { "missingProperty": "username" }, "message": "must have required property 'username'" } ] } ``` This behavior suggests that the `username` is missing, but I can see it is present in the request body. I've verified that the request payload is being sent correctly, and I've also checked that `express.json()` middleware is included in the app. I would love any insights on why this validation might be failing and how I can debug this scenario further. Any advice on best practices for using Ajv with TypeScript in an Express environment would also be appreciated. This is happening in both development and production on Windows 11. What's the best practice here?