@gocodingnow/rn-native-base-boilerplate/template/src/utils/mmkv.ts

React Native + Native Base Boilerplate

import {MMKV, MMKVConfiguration} from 'react-native-mmkv'

export class Storage {
  private static _instance: Storage
  private _storage: MMKV
  constructor(configuration?: MMKVConfiguration) {
    this._storage = new MMKV(configuration)
  }

  static get instance() {
    return Storage._instance
  }

  public static setup(configuration?: MMKVConfiguration) {
    if (!Storage.instance) {
      Storage._instance = new Storage(configuration)
    }
    return Storage._instance
  }

  getStorage() {
    return this._storage
  }

  /**
   * Loads a string from storage.
   *
   * @param key The key to fetch.
   */
  getItem(key: string, type?: 'number' | 'string' | 'boolean' | 'object') {
    if (type === 'number') {
      return this._storage.getNumber(key)
    }
    if (type === 'boolean') {
      return this._storage.getBoolean(key)
    }
    if (type === 'object') {
      try {
        const jsonObject = this._storage.getString(key)
        return JSON.parse(jsonObject as any)
      } catch {
        return null
      }
    }
    return this._storage.getString(key)
  }

  /**
   * Saves a string to storage.
   *
   * @param key The key to fetch.
   * @param value The value to store.
   */
  setItem(key: string, value: string | number | boolean | object) {
    let targetValue
    if (typeof value === 'object') {
      targetValue = JSON.stringify(value)
    } else {
      targetValue = value
    }
    return this._storage.set(key, targetValue)
  }

  /**
   * Removes something from storage.
   *
   * @param key The key to kill.
   */
  removeItem(key: string) {
    return this._storage.delete(key)
  }

  /**
   * Burn it all to the ground.
   */
  clearAll() {
    return this._storage.clearAll()
  }
}

export const getAsyncStorage = (storage: Storage) => ({
  setItem: (key: string, value: string): Promise<void> => {
    storage.setItem(key, value)
    return Promise.resolve()
  },
  getItem: (key: string): Promise<string | null> => {
    const value = storage.getItem(key)
    return Promise.resolve(value)
  },
  removeItem: (key: string): Promise<void> => {
    storage.removeItem(key)
    return Promise.resolve()
  },
})