Express Input Validation (Zod)

npm install zod

const { z } = require("zod");

const createUserSchema = z.object({
  name: z.string().min(2, "নাম কমপক্ষে 2 অক্ষর").max(50),
  email: z.string().email("সঠিক email দিন"),
  age: z.number().int().min(18).max(120).optional(),
  password: z.string().min(6, "পাসওয়ার্ড কমপক্ষে 6 অক্ষর"),
});

const updateUserSchema = z.object({
  name: z.string().min(2).max(50).optional(),
  age: z.number().int().min(18).max(120).optional(),
});

module.exports = { createUserSchema, updateUserSchema };

const validate = (schema) => (req, res, next) => {
  const result = schema.safeParse(req.body);

  if (!result.success) {
    const errors = result.error.issues.map(issue => ({
      field: issue.path.join("."),
      message: issue.message,
    }));
    return res.status(400).json({ error: "Validation failed", errors });
  }

  req.body = result.data; // cleaned data
  next();
};

module.exports = validate;

const validate = require("../middleware/validate");
const { createUserSchema } = require("../validators/userValidator");

router.post("/", validate(createUserSchema), async (req, res) => {
  const user = await User.create(req.body);
  res.status(201).json(user);
});

POST /api/users
{ "name": "A", "email": "bad-email" }

Response:
{
  "error": "Validation failed",
  "errors": [
    { "field": "name", "message": "নাম কমপক্ষে 2 অক্ষর" },
    { "field": "email", "message": "সঠিক email দিন" }
  ]
}