Migrate type validators to `zod`

[nicholaschiang]

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Instead of declaring a type and then declaring the JSON validator for that type separately, I should use a library like zod to only do it once (and then have a single source of truth instead of duplicating code and creating more possibilities for bugs).

[nicholaschiang]

See the validators in lib/model, for example, in lib/model/user.ts:

export interface UserInterface extends AccountInterface {
  age?: number;
  orgs: string[];
  zooms: ZoomUser[];
  availability: Availability;
  mentoring: Subjects;
  tutoring: Subjects;
  langs: string[];
  parents: string[];
  verifications: Verification[];
  visible: boolean;
  featured: Aspect[];
  roles: Role[];
  tags: UserTag[];
  reference: string;
  timezone: string;
  token?: string;
  hash?: string;
}

export function isUserJSON(json: unknown): json is UserJSON {
  if (!isAccountJSON(json)) return false;
  if (!isJSON(json)) return false;
  if (json.age && typeof json.age !== 'number') return false;
  if (!isStringArray(json.orgs)) return false;
  if (!isArray(json.zooms, isZoomUserJSON)) return false;
  if (!isAvailabilityJSON(json.availability)) return false;
  if (!isSubjects(json.mentoring)) return false;
  if (!isSubjects(json.tutoring)) return false;
  if (!isStringArray(json.langs)) return false;
  if (!isStringArray(json.parents)) return false;
  if (!isArray(json.verifications, isVerificationJSON)) return false;
  if (typeof json.visible !== 'boolean') return false;
  if (!isArray(json.featured, isAspect)) return false;
  if (!isArray(json.roles, isRole)) return false;
  if (!isArray(json.tags, isUserTag)) return false;
  if (typeof json.reference !== 'string') return false;
  if (typeof json.timezone !== 'string') return false;
  if (json.token && typeof json.token !== 'string') return false;
  if (json.hash && typeof json.hash !== 'string') return false;
  return true;
}

All of that ☝️ could have been written once using a zod type validator.

[nicholaschiang]

Also, zod is nicer because it throws the specific validation error instead of simply returning false (like the above validator function). That way, the client knows exactly why it got a 400 - Invalid Request Body API error and how to fix it.

[jasonappah]

I'd love to take this issue! Is there anything else I should be aware of before working on this?