Eosis

// MeetingCodec.ts
import * as T from 'io-ts'
import BaseMeetingCodecT from '../../shared/codecs/BaseMeetingCodec'
import JustStartTimeT from './JustStartTimeCodec'
const MeetingT = T.intersection([BaseCodecT, JustStartTimeT])

export default MeetingT

Eosis

// The type we get from on retrieving the document from firestore:
type FromFirestore = {
  "meetingAgenda": string
  "startTime": firestore.Timestamp // 😱 This is a different type between the client and the admin sdks.
}

// The type we want in in our Frontend and Backend:
type Meeting = {
  meetingAgenda: string,
  startTime: Luxon.DateTime

Eosis

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /users/{userId} {
      allow read: if request.auth != null
      match /private/info {
        allow write: if request.auth && request.auth.uid == userId
        allow read: if request.auth && request.auth.uid == userId
      }
    }

Eosis

// Collection at /users/rzJZAyMbXaeXQ9OWeIckM88DUcq1
{
  "name": "Rupert",            // I'm happy for people to see this
}

// Collection at /users/rzJZAyMbXaeXQ9OWeIckM88DUcq1/private/info
{
  "email": "me@example.com",   // I can be hidden now!
  "birthday": "1970-01-01"     // I can be hidden now!
}

Eosis

const superSecretEmail = userDoc.data().email.       // 😱
const superSecretBirthday = userDoc.data().birthday  // 😱

Eosis

const userDoc = await getDoc(doc(db, '/users/', uid))
const name = userDoc.data().name

Eosis

// Collection at /users/rzJZAyMbXaeXQ9OWeIckM88DUcq1
{
  "name": "Rupert",                        // I'm happy for people to see this
  "email": "me@example.com",               // I'd rather they didn't see this
  "birthday": "1970-01-01"                 // I'd rather they didn't see this
}

Eosis

import * as T from 'io-ts'
import BaseMeetingCodecT from '../../shared/codecs/BaseMeetingCodec'
import JustStartTimeT from './JustStartTimeCodec'
const MeetingT = T.intersection([BaseCodecT, JustStartTimeT])

export default MeetingT

Eosis

// Client LuxonTimestampCodec:
import * as T from 'io-ts'
import { DateTime } from 'luxon'
import { Timestamp } from 'firebase/firestore'

const LuxonDateTimeT = new T.Type<DateTime, Timestamp, unknown>(
  'LuxonDateTimeT',
  (u: unknown): u is DateTime => u instanceof DateTime,
  (u: unknown, c: T.Context) => {
    if (!(u instanceof Timestamp)) {

Eosis

// Backend TimestampCodec
import * as T from 'io-ts'
import { DateTime } from 'luxon'
import * as admin from 'firebase-admin'

export const LuxonDateTimeT = new T.Type<DateTime, admin.firestore.Timestamp, unknown>(
  'LuxonDateTimeT',
  (u: unknown): u is DateTime => u instanceof DateTime,
  (u: unknown, c: T.Context) => {
    if (!(u instanceof admin.firestore.Timestamp)) {