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Validating Request Data in Express.js using Zod and TypeScript: A Comprehensive Guide

Stephen Akugbe on January 15, 2024

Introduction Express.js is a popular web framework for building Node.js applications, and validation is a crucial aspect of handling inc...

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Adriel • May 28 '24

Really useful, thanks!

Stephen Akugbe • May 28 '24

Thank you @adrielfsantos

Vignesh Murugan • Mar 28 '24

This is great, right to the point.
Thanks!!!!

Stephen Akugbe • Apr 3 '24

Thank you Vignesh

Ron Zano • Aug 25 '24

Very nice!

obei • Sep 16 '24

amazing and simple thx

Hrithik Raj • Oct 3 '24

Thanks

Bello Shehu • Feb 5 '25

Good one. Very concise

Carlos Eduardo • Jul 28 '24

How can i validate the params too? Great article, thanks!

andonov85 • Oct 18 '24

You can try something like this for a validation.middleware.ts:

import { RequestHandler } from 'express';
import { ZodTypeAny, z } from 'zod';

const validate = (
  schema: ZodTypeAny,
  source: 'body' | 'params' | 'query'
): RequestHandler => {
  return async (req, res, next) => {
    try {
      await schema.parseAsync(req[source]);
      next();
    } catch (err) {
      if (err instanceof z.ZodError) {
        res.status(400).json({
          message: `Invalid ${source} schema`,
          errors: err.errors,
        });
      } else {
        next(err);
      }
    }
  };
};

const validateRequestBody = (schema: ZodTypeAny): RequestHandler => {
  return validate(schema, 'body');
};

const validateRequestParams = (schema: ZodTypeAny): RequestHandler => {
  return validate(schema, 'params');
};

const validateRequestQuery = (schema: ZodTypeAny): RequestHandler => {
  return validate(schema, 'query');
};

export { validateRequestBody, validateRequestParams, validateRequestQuery };

CS • Jan 17 • Edited

Thank you for the good article. Maybe I am wrong, but this does not give you type safety inside the controller. If I want to access req.body in the controller, its type is still "any". Sadly you would need to infer the type of the body from your schema.