Approach for offline ReactNative
3 min readOct 17, 2023
Build your React Native app so that it can work with or without an Internet connection.
- Use a local database to store data. This will allow your app to continue functioning even when the user is offline.
- Cache data from the server. When the user is online, fetch data from the server and store it in the local database. This will allow your app to display the cached data when the user is offline.
- Handle network errors gracefully. When the user is offline or when there is a network error, your app should display a helpful message and allow the user to continue using the app as much as possible.
Here are some specific libraries and tools that you can use to make an offline-first React Native app:
- AsyncStorage: A simple key-value store for persisting data locally on the device.
- Realm: A mobile database that can be used to store and manage complex data structures.
- WatermelonDB: A lightweight, NoSQL database for React Native.
- React Native Offline: A library that provides a number of utilities for making offline-first React Native apps, such as network state detection and offline caching.
you will need to check the network state before fetching data from the server. If the user is offline, you will need to display the cached data.
useEffect(() => {
NetInfo.addEventListener('connectionChange', handleConnectionChange);
// Get the cached users data
AsyncStorage.getItem('users').then(users => {
//better use a custom function that returns the JSON.parse(resposne)
if (users) {
setUsers(JSON.parse(users));
}
});
//clean the function
return () => {
NetInfo.removeEventListener('connectionChange', handleConnectionChange);
};
}, []);
const handleConnectionChange = (state) => {
setIsOnline(state.isConnected);
};
// Fetch users from the server if the user is online and there is no cached data
if (isOnline && !users.length) {
//.....some datas to fetched You can use this same approach to cache any type of data, such as images, videos, or other resources.
Making an offline-first React Native app can be more challenging than making an online-only app, but it is worth it to provide a better user experience.
Tools to Consider for Building Offline Applications
Cloud Firestore
Cloud Firestore is a NoSQL document database provided by Google designed to store, sync, and query data, offering built-in features such as offline data persistence and real-time data synchronization.
Pros
- Easy to implement: Comprehensive documentation and a well-supported client library make it easy to get started.
- Automatic data synchronization: Offline changes are automatically synchronized with the server.
Cons
- Cost and scalability: Firestore can become expensive beyond the free tier.
- Hard to migrate: Firestore is tightly coupled with the Firebase ecosystem, so it can be challenging to migrate to other data storage alternatives in the future.
Redux Offline
Redux Offline is a persistent store for building offline-first applications with first-class support for optimistic UI powered by Redux.
Pros
- Extension of Redux: Redux Offline is an extension of Redux, making it easy to integrate into existing Redux-based applications.
- Support for optimistic UI: Even offline, users can see their actions immediately on the UI. It also provides a way to make rollbacks if needed.
Cons
- Complexity: Redux can add unnecessary complexity to your codebase (depending on the app context)
- Coupled with Redux: Redux Offline is tightly coupled with Redux, which may not be suitable for apps using alternative state management approaches.