expo-secure-store-adapter.ts

import * as SecureStore from 'expo-secure-store';
import { chunk } from 'lodash';

const chunkString = (str: string, size: number) =>
  chunk(str.split(''), size).map(s => s.join(''));

/**
 * Secure Storage with support for storing strings larger than 2048 characters
 */
const ExpoSecureStoreAdapter = {
  getItem: async (key: string) => {
    const value = await SecureStore.getItemAsync(key);

    if (value === null) {
      let chunkedValue = '';
      let done = false;
      let index = 0;
      while (!done) {
        const v = await SecureStore.getItemAsync(`${key}_chunk_${index}`);
        if (v === null) {
          done = true;
        } else {
          chunkedValue += v;
        }
        index++;
      }

      if (chunkedValue) {
        return chunkedValue;
      }
    }

    return value;
  },
  setItem: async (key: string, value: string) => {
    if (value.length > 2048) {
      const values = chunkString(value, 2048);
      await Promise.all(
        values.map((v, i) => SecureStore.setItemAsync(`${key}_chunk_${i}`, v))
      );
    } else {
      return SecureStore.setItemAsync(key, value);
    }
  },
  // HACK: No way of knowing if we have removed all chunks
  removeItem: async (key: string) => {
    await Promise.all([
      SecureStore.deleteItemAsync(key),
      SecureStore.deleteItemAsync(`${key}_chunk_0`),
      SecureStore.deleteItemAsync(`${key}_chunk_1`),
      SecureStore.deleteItemAsync(`${key}_chunk_2`),
      SecureStore.deleteItemAsync(`${key}_chunk_3`)
    ]);
  }
};

export default ExpoSecureStoreAdapter;