Remote Config Plugin

Add the plugin

remoteConfig() is a client plugin exported from @hot-updater/react-native. Pass it to plugins in HotUpdater.init with your in-app defaults, and use it as hotUpdater.remoteConfig on the instance init returns:

import { HotUpdater, remoteConfig } from "@hot-updater/react-native";

export const hotUpdater = HotUpdater.init({
  baseURL: "<your-update-server-url>",
  requestHeaders: { "x-api-key": "<your-api-key>" },
  plugins: [
    remoteConfig({ 
      defaults: { welcome_message: "Welcome back", max_items: 20 },
    }),
  ],
});

It fetches GET /remote-config under baseURL, with the requestHeaders and requestTimeout of init, from a server that runs the remoteConfig() server plugin, as the managed servers do. The Remote Config guide covers publishing values.

Options

Read values

Reads are synchronous and return the first of these that has the key:

1. the value the app activated last, stored on the device;
2. the key's value in defaults;
3. null.

A fresh install has activated nothing, so it reads defaults, and null for any other key, until its first fetch and activate succeed. init loads the values an earlier launch activated before it returns, so later launches render them from the first frame.

Keys declared in defaults always have a value, so their reads are typed without null; other keys are typed T | null:

const config = hotUpdater.remoteConfig;
config.getNumber("max_items"); // number: max_items is in defaults
config.getString("promo_code") ?? ""; // string | null without the fallback

false, 0, and "" are values, never null. A JSON parameter arrives as text: JSON.parse(config.getString("layout")). When a later version leaves a key to the app, reads return its default again, or null without one.

Fetch and activate

// Apply as soon as they arrive:
hotUpdater.remoteConfig.fetchAndActivate().catch(() => {});

// Or apply at the next launch: activate what the last launch fetched,
// then fetch for the next one.
await hotUpdater.remoteConfig.activate();
hotUpdater.remoteConfig.fetch().catch(() => {});

• A fetch within minimumFetchIntervalMs of the last successful one reuses the values fetched last and sends nothing, unless the channel, native version, cohort, or fingerprint changed. { force: true } asks the server anyway; every forced fetch is a request, so use it for a moment such as pull to refresh, or as the guide's kill switch does.
• Concurrent calls share one fetch, and an unchanged answer is a 304.
• fetch() rejects, and the active values stay, when the request fails or times out, or the server answers an error, such as 404 from a server without remoteConfig(). A failed fetch doesn't start the interval.
• Fetched and active values are stored on the device, outside backups, and survive restarts and OTA updates. Fetching works in debug builds too.

Status

These persist across launches.

Re-render on activation

subscribe(listener) calls listener whenever activate() changes the values, and returns a function that stops it. getAll() returns the same object until then, so the pair works with useSyncExternalStore:

import { useSyncExternalStore } from "react";

import { hotUpdater } from "./hotUpdater";

export const useRemoteConfig = () =>
  useSyncExternalStore(
    hotUpdater.remoteConfig.subscribe,
    hotUpdater.remoteConfig.getAll,
  );

const values = useRemoteConfig();
return <Text>{values.welcome_message?.asString()}</Text>;

Types

@hot-updater/react-native exports RemoteConfigClient (the type of hotUpdater.remoteConfig), RemoteConfigPlugin, RemoteConfigOptions, RemoteConfigValue, RemoteConfigValueSource, RemoteConfigFetchStatus, RemoteConfigFetchOptions, RemoteConfigDefaults, RemoteConfigDefaultValue, and RemoteConfigKey.