Mobx State Tree Persistent Store

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

• Installation
  • For React
  • For React Native
• Usage
  • Create Provider and Hooks
  • Add Provider to The Root Component
  • Use the Store from Child Components
• Custom Storage Backend
• API
  • createPersistentStore
    • Type Definition
    • Arguments
    • PersistentStoreOptions
• Notes
  • disallowList
• License
• Contribution

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';
// The default storage is async-storage for React Native and localforage for Web
// This needs to be explicitly imported for the default storage to work correctly
// for the respective platform. If you are using a custom storage,
// you don't need to import this
import defaultStorage from 'mst-persistent-store/dist/storage';

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

export const [PersistentStoreProvider, usePersistentStore] = createPersistentStore(
  PersistentStore,
  defaultStorage,
  {
    name: 'Test User',
    age: 19,
    premium: 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 store = usePersistentStore();

  return (
    <div>
      <p>
        {store.name} is {store.age} years old and {store.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,
  }
);

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<T extends IAnyModelType> {
  storageKey: string;
  writeDelay: number;
  logging: boolean;
  devtool: boolean;
  onHydrate?: (store: Instance<T>) => void;
}
const createPersistentStore: <T extends IAnyModelType>(
  store: T,
  storage: StorageOptions,
  init: SnapshotIn<T>,
  disallowList?: PartialDeep<SnapshotIn<T>>,
  options?: Partial<PersistentStoreOptions<T>>
) => 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/dist//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
disallowList	PartialDeep<SnapshotIn<T>>	no	the part of the store that should not be persisted. See notes below
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 same app to avoid overriding data.
writeDelay	number	1500	On Repeated Store Update, it's advisable to wait a certain time before updating the persistent storage with new snapshot. This value controls the debounce delay.
logging	boolean	true is dev false in prod	Whether to enable logging.
devtool	boolean	true in dev false in prod	Whether to integrate with mobx-devtool
onHydrate	(store: Instance<T>) => void	none	Callback to run after hydration is done.

Notes

disallowList

disallowList is used to specify the part of the store that should not be persisted. This is useful when you have some part of the store that should not be persisted. For example, you may have a part of the store that is used for UI state management and should not be persisted.

This is a deep partial of the store snapshot. Anything passed here will replace the value on hydration.

License

This package is licensed under the MIT License.

Contribution

Any kind of contribution is welcome. Thanks!