Mst-persistent-store NPM

Mobx State Tree Persistent Store

A factory to easily create Persistent Mobx State Tree Store Provider and consumer hook.

Installation

yarn add mst-persistent-store

@react-native-async-storage/async-storage and localforage are optional peer dependencies. You can use any storage you want by passing the storage object to the factory. But if you want to use the default storage, you need to install one of them. See Usage and Custom Storage Backend for more info about how to use default or custom storage.

For React

yarn add mobx-state-tree localforage

For React Native

yarn add mobx-state-tree @react-native-async-storage/async-storage

Usage

Usage is very simple.

Create Provider and Hooks

Below is an example on how to create the provider and consumer hook.

// store-setup.ts
import { types } from 'mobx-state-tree';
import createPersistentStore from 'mst-persistent-store';
import defaultStorage from 'mst-persistent-store/dist/storage';

const PersistentStore = types
  .model('RootStore', {
    name: types.string,
    age: types.number,
    premium: types.boolean,
    hydrated: types.boolean,
  })
  .actions((self) => ({
    hydrate() {
      self.hydrated = true;
    },
  }))
  .views((self) => ({
    get isAdult() {
      return self.age >= 18;
    },
  }));

export const [PersistentStoreProvider, usePersistentStore] = createPersistentStore(
  PersistentStore,
  defaultStorage,
  {
    name: 'Test User',
    age: 19,
    premium: false,
    hydrated: false,
  },
  {
    hydrated: false,
  },
  {
    logging: false,
    devtool: false,
  }
);

Add Provider to The Root Component

Wrap your app with the created Provider component.

// app.tsx
import { PersistentStoreProvider } from './store-setup';
import Main from './main';

export default function App() {
  return (
    <PersistentStoreProvider>
      <Main />
    </PersistentStoreProvider>
  );
}

Use the Store from Child Components

Consume store values using the hook.

// main.tsx
import { observer } from 'mobx-react-lite';
import { useEffect } from 'react';
import { usePersistentStore } from './store-setup';

const Main = observer(() => {
  const { name, age, isAdult, hydrated, hydrate } = usePersistentStore();

  useEffect(() => {
    hydrate();
  }, []);

  if (!hydrated) {
    return <p>Loading...</p>;
  }

  return (
    <div>
      <p>
        {name} is {age} years old and {isAdult ? 'is' : 'is not'} an adult.
      </p>
    </div>
  );
});

export default Main;

Custom Storage Backend

The above example uses the default storage. You can use any storage you want by passing the storage object to the factory.

Here is an example using react-native-mmkv as the storage.

import { MMKV } from 'react-native-mmkv';

const mmkv = new MMKV();

const setItem = (key: string, value: any) => mmkv.set(key, JSON.stringify(value));

const getItem = (key: string) => {
  const value = mmkv.getString(key);
  if (value) {
    return JSON.parse(value);
  }
  return null;
};

const removeItem = (key: string) => mmkv.delete(key);

const storage = {
  setItem,
  getItem,
  removeItem,
};

export const [PersistentStoreProvider, usePersistentStore] = createPersistentStore(
  PersistentStore,
  storage,
  {
    name: 'Test User',
    age: 19,
    premium: false,
    hydrated: false,
  },
  {
    hydrated: false,
  },
  {
    hydrated: false,
  }
);

API

createPersistentStore

Type Definition

export interface StorageOptions {
  setItem: (key: string, value: any) => Promise<void> | void;
  getItem: (key: string) => Promise<any | null> | any | null;
  removeItem: (key: string) => Promise<void> | void;
}

interface PersistentStoreOptions {
  storageKey: string;
  writeDelay: number;
  logging: boolean;
  devtool: boolean;
}
const createPersistentStore: <T extends IAnyModelType>(
  store: T,
  storage: StorageOptions,
  init: SnapshotIn<T>,
  blacklist?: PartialDeep<SnapshotIn<T>>,
  options?: Partial<PersistentStoreOptions>
) => readonly [React.FC, () => Instance<T>];

Arguments

param	type	required	description
store	`T extends IAnyModelType`	yes	the mst model to instantiate
storage	`StorageOptions`	yes	the storage to use. Use `defaultStorage` from `mst-persistent-store/storage` to use the `@react-native-async-storage/async-storage` (for React Native) or `localforage` (for Web) backed default storage.
init	`SnapshotIn<T>`	yes	the init data of the store
blacklist	`PartialDeep<SnapshotIn<T>>`	no	the part of the store that should not be persisted
options	`Partial<PersistentStoreOptions>`	no	Various options to change store behavior

PersistentStoreOptions

All Properties are optional.

property	type	default	description
storageKey	`string`	persistentStore	the key to use as the localforage key. Must be changed when using multiple stores in the sameapp to avoid overriding data.
writeDelay	`number`	1500	On Repeated Store Update, it's advisable to waita certain time before updating the persistent storage with new snapshot. This value controls thedebounce delay.
logging	`boolean`	true is devfalse in prod	Whether to enable logging.
devtool	`boolean`	true in devfalse in prod	Whether to integrate with mobx-devtool