Storing local data is a fundamental requirement for many mobile applications. React Native Expo provides several methods to handle local data storage effectively. In this blog, we’ll explore three primary solutions: AsyncStorage, SecureStore, and SQLite, discussing their features, use cases, and benefits.

AsyncStorage

AsyncStorage is a simple, unencrypted, asynchronous key-value storage system. It is easy to use and is suitable for storing small amounts of data that need to persist across app launches, such as user preferences and settings.

Features:

• Asynchronous operations
• Persistent storage
• Simple API

Use Cases:

• Storing user preferences and settings
• Caching small pieces of data
• Saving non-sensitive information

Example:

To store data using AsyncStorage, you can use the setItem method:

import AsyncStorage from '@react-native-async-storage/async-storage';

const storeData = async (key, value) => {
  try {
    await AsyncStorage.setItem(key, value);
    console.log('Data stored successfully');
  } catch (error) {
    console.error('Error storing data', error);
  }
};

SecureStore

SecureStore provides a secure way to store sensitive data, such as authentication tokens and user credentials. It leverages the device's secure storage mechanisms like iOS Keychain and Android Keystore, ensuring high security.

Features:

• High security with encryption
• Platform-specific secure storage
• Asynchronous operations

Use Cases:

• Storing authentication tokens
• Saving user credentials
• Keeping sensitive configuration settings

Example:

To store data securely using SecureStore, you can use the setItemAsync method:

import * as SecureStore from 'expo-secure-store';

const storeSecureData = async (key, value) => {
  try {
    await SecureStore.setItemAsync(key, value);
    console.log('Data stored securely');
  } catch (error) {
    console.error('Error storing secure data', error);
  }
};

SQLite

SQLite is a powerful, embedded SQL database engine suitable for handling large datasets and complex data relationships. It supports SQL queries and provides robust database management capabilities.

Features:

• Supports complex queries and relational data
• Efficient storage for large datasets
• Persistent and reliable

Use Cases:

• Managing large datasets
• Offline-first applications
• Apps requiring advanced querying capabilities

Example:

To create a table and insert data using SQLite, you can use the executeSql method:

import * as SQLite from 'expo-sqlite';

const db = SQLite.openDatabase('myDatabase.db');

const createTable = () => {
  db.transaction(tx => {
    tx.executeSql(
      'CREATE TABLE IF NOT EXISTS users (id INTEGER PRIMARY KEY NOT NULL, name TEXT, age INTEGER);'
    );
  });
};

const insertData = (name, age) => {
  db.transaction(tx => {
    tx.executeSql(
      'INSERT INTO users (name, age) values (?, ?)',
      [name, age],
      (txObj, resultSet) => console.log('Data inserted', resultSet),
      (txObj, error) => console.error('Error inserting data', error)
    );
  });
};

Choosing the right local storage solution in React Native Expo depends on your specific needs. AsyncStorage is perfect for simple key-value storage, SecureStore is ideal for secure data storage, and SQLite excels at handling complex datasets and relational data. Understanding these options will help you implement effective data storage strategies in your mobile applications.