Optionals

You can make any schema optional with z.optional(). This wraps the schema in a ZodOptional instance and returns the result.

const schema = z.optional(z.string());
 
schema.parse(undefined); // => returns undefined
type A = z.infer<typeof schema>; // string | undefined

For convenience, you can also call the .optional() method on an existing schema.

const user = z.object({
  username: z.string().optional()
});
type C = z.infer<typeof user>; // { username?: string | undefined };

You can extract the wrapped schema from a ZodOptional instance with .unwrap().

const stringSchema = z.string();
const optionalString = stringSchema.optional();
optionalString.unwrap() === stringSchema; // true