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Schema validation ​

Validation libraries ​

When a client sends us a large object, checking each property one by one is tedious. There are libraries such as Yup and Joi to help with this. We'll be using Zod.

Creating a schema ​

We can create a schema using Zod.

js
import { z } from 'zod'

const UserSchema = z.object({
  username: z.string(),
  firstName: z.string(),
  lastName: z.string(),
  email: z.string().email(),
  avatar: z.string().optional(),
  password: z.string()
})

Validating data ​

When a user sends us some data (which we will call the payload) we need to check that it matches the schema, i.e. that it has the correct properties and that they are of the correct type.

js
const valid = UserSchema.safeParse(payload).success

if (!valid) {
  throw new AppError('User data is not valid.', 400)
}

// if the error is not thrown, we can be confident that
// the payload has the correct properties

Do check out the Zod docs to find out more about what it can do.