Patching expo for expo-constants, expo-linking and expo-font to work in Bare Workflow

README.md

Patching Expo to work in all workflows (Bare and Managed)

{
  "expo": {
    "entryPoint": "index.js"
  }
}

expo-constants.ts

/*
 * In the SDK38 Bare Workflow `expo-constants` does not expose all values in all situations.
 *
 * Situations:
 *  running in Expo Client with JS from `expo start`
 *  running in Standalone with JS from `react-native start`
 *  running in Standalone with JS bundled
 *
 * Documentation:
 *  https://docs.expo.io/guides/environment-variables/
 *  https://docs.expo.io/versions/v38.0.0/sdk/constants/
 *  https://docs.expo.io/versions/v38.0.0/sdk/updates/
 *
 * Issues:
 *  https://github.com/expo/expo/issues/7721
 *  https://forums.expo.io/t/error-after-ejecting-to-bare-workflow-null-is-not-an-object-error-evaluating-expoconstants-default-manifest-releasechannel/28497/3
 */

import Constants, { AppOwnership } from 'expo-constants'
import { AppManifest } from 'expo-constants/build/Constants.types'
import * as Updates from 'expo-updates'

import manifestJson from '$src/../app.json'

const manifest: AppManifest = (
  // in Expo Client with JS from `expo start`
  // in Standalone with JS bundled
  Constants.manifest ||
  // in Standalone with JS from `react-native start`
  { ...manifestJson.expo, bundleUrl: '' }
)

const appOwnership: AppOwnership = (
  // in Expo Client with JS from `expo start`
  // https://docs.expo.io/versions/v38.0.0/sdk/constants/#constantsappownership
  Constants.appOwnership ||
  // in Standalone with JS from `react-native start`
  AppOwnership.Standalone
)

const releaseChannel = (
  // running in Standalone with JS bundled
  Updates.releaseChannel ||
  // everywhere else (the default value of `Updates.releaseChannel`)
  'default'
)

const expoVersion = (
  // in Expo Client with JS from `expo start`
  Constants.expoVersion ||
  // everywhere else
  null
)

// available from expo-constants in every situation
// https://docs.expo.io/versions/v38.0.0/sdk/constants/#constantsdevicename
const deviceName = Constants.deviceName

// available from expo-constants in every situation
// https://docs.expo.io/versions/v38.0.0/sdk/constants/#constantsdeviceyearclass
const deviceYearClass = Constants.deviceYearClass

// available from expo-constants in every situation
// https://docs.expo.io/versions/v38.0.0/sdk/constants/#constantsinstallationid
const installationId = Constants.installationId

// available from expo-constants in every situation
// https://docs.expo.io/versions/v38.0.0/sdk/constants/#constantsisdevice
const isDevice = Constants.isDevice

// available from expo-constants in every situation
// https://docs.expo.io/versions/v38.0.0/sdk/constants/#constantsnativeappversion
const nativeAppVersion = String(Constants.nativeAppVersion)

// available from expo-constants in every situation
// https://docs.expo.io/versions/v38.0.0/sdk/constants/#constantsnativebuildversion
const nativeBuildVersion = String(Constants.nativeBuildVersion)

// available from expo-constants in every situation
// https://docs.expo.io/versions/v38.0.0/sdk/constants/#constantsplatform
const platform = Constants.platform

// available from expo-constants in every situation
// https://docs.expo.io/versions/v38.0.0/sdk/constants/#constantssessionid
const sessionId = Constants.sessionId

// available from expo-constants in every situation
// https://docs.expo.io/versions/v38.0.0/sdk/constants/#constantsstatusbarheight
const statusBarHeight = Constants.statusBarHeight

// available from expo-constants in every situation
// https://docs.expo.io/versions/v38.0.0/sdk/constants/#constantssystemfonts
const systemFonts = Constants.systemFonts

export {
  appOwnership,
  deviceName,
  deviceYearClass,
  expoVersion,
  installationId,
  isDevice,
  manifest,
  nativeAppVersion,
  nativeBuildVersion,
  platform,
  releaseChannel,
  sessionId,
  statusBarHeight,
  systemFonts,
}

index.expo-constants.hacks.ts

/* eslint-disable no-import-assign */
/*
 * WARNING!
 *
 * This file contains ugly hack-arounds because expo-constants
 * does not yet know its place in the Bare Workflow.
 * Eventually all of this should become obsolete
 */

import { Platform } from 'react-native'
import { Asset } from 'expo-asset'
import Constants, { ExecutionEnvironment } from 'expo-constants'
import ExpoFontLoader from 'expo-font/build/ExpoFontLoader'
import { FontResource } from 'expo-font/build/Font.types'
import * as FontLoader from 'expo-font/build/FontLoader'
import * as Linking from 'expo-linking/build/Linking'
import { CodedError } from '@unimodules/core'

import { appOwnership, manifest } from './expo-constants'
import Config from '$src/native/react-native-config'

// Patch Constants for expo-linking
// In order for the patch to take effect this file has to be executed before expo-linking is loaded
// https://github.com/expo/expo/blob/7592d4d/packages/expo-linking/src/Linking.ts#L13
if (Constants.appOwnership === null) {
  Constants.appOwnership = appOwnership
  Constants.manifest = manifest
}

// Patch expo-linking to construct URL when not in expo client
// https://github.com/expo/expo/blob/7592d4d/packages/expo-linking/src/Linking.ts#L114
if (Constants.executionEnvironment === ExecutionEnvironment.Bare) {
  const _makeUrl = Linking.makeUrl
  // @ts-expect-error
  Linking.makeUrl = (path = '', queryParams?: Linking.QueryParams) => {
    Constants.executionEnvironment = ExecutionEnvironment.StoreClient
    const result = _makeUrl(path, queryParams)
    Constants.executionEnvironment = ExecutionEnvironment.Bare
    return result
  }
}

// Patch expo-font to load fonts when in `npm run rn:ios`
// https://github.com/expo/expo/blob/1e8f40c/packages/expo-font/src/FontLoader.ts#L10
if (Config.BUILD_CONFIG === 'debug' && Platform.OS === 'ios') {
  // @ts-expect-error
  FontLoader.fontFamilyNeedsScoping = () => false
  // @ts-expect-error
  FontLoader.getNativeFontName = (name: string) => name
  // @ts-expect-error
  FontLoader.loadSingleFontAsync = async (
    name: string,
    input: Asset | FontResource,
  ): Promise<void> => {
    const asset = input as Asset
    if (!asset.downloadAsync) {
      throw new CodedError(
        'ERR_FONT_SOURCE',
        '`loadSingleFontAsync` expected resource of type `Asset` from expo-asset on native',
      )
    }

    await asset.downloadAsync()
    if (!asset.downloaded) {
      throw new CodedError('ERR_DOWNLOAD', `Failed to download asset for font "${name}"`)
    }
    await ExpoFontLoader.loadAsync(FontLoader.getNativeFontName(name), asset.localUri)
  }
}

index.js

// intentionally sorted manually
/* eslint-disable simple-import-sort/imports */

// https://reactnavigation.org/docs/getting-started/#installing-dependencies-into-a-bare-react-native-project
import 'react-native-gesture-handler'

import './index.expo-constants.hacks.ts'

// https://docs.expo.io/bare/installing-updates/#configuration-in-javascript-and-json
import 'expo-asset'

// originally from: node_modules/expo/AppEntry.js
import registerRootComponent from 'expo/build/launch/registerRootComponent'
import App from './App'

registerRootComponent(App)