Prerequisite

    npm i joi

Task 1 : Create UserSchemaValidator (user.schema.validator.js)

    const Joi = require('joi');

    const options = {
    abortEarly: false, // include all errors
    allowUnknown: true, // ignore unknown props
    stripUnknown: true // remove unknown props
    };

    class UserSchemaValidator {

        async createUserSchema (req,res,next){
            const schema = Joi.object({
                name: Joi.string().required(),
                email: Joi.string().email().required(),
                password: Joi.string().min(6).required(),
                role: Joi.string().valid('ADMIN', 'USER').required()
            });

            try{
                let result = await schema.validateAsync(req.body, options);
                console.log("Result:", result);
                next();
            }
            catch(error){    
               this.handleError(error,res);
            }
        }  
        handleError(error, res) {
            let errorMessages = error.details.map(x => ({ field: x.path[0], message: x.message }));
            console.error(JSON.stringify(errorMessages));
            let result = { status: 400, errors: errorMessages };
            res.status(400).json(result);
        } 
    }

    exports.UserSchemaValidator = UserSchemaValidator;

Task 2: Add Schema Validation in user routes - create user api ( users.router.js)

    const express = require('express');
    const router = express.Router();

    const {UserController} = require("./user.controller");
    const userController = new UserController();

    const {UserSchemaValidator} = require("./user.schema.validator")

    const userSchemaValidator = new UserSchemaValidator();
    router.get('/',  userController.getAllUsers);

    //router.post('/', userController.createUser); // Without Schema Validation
    router.post('/', userSchemaValidator.createUserSchema, userController.createUser);

    module.exports = router;