mobx-sync-lite

mobx-sync-lite is a library that uses JSON to persist your MobX stores with version control. It is a fork of mobx-sync with the goal of supporting current versions of MobX.

Features

• use JSON.stringify/JSON.parse as the deserialize/serialize method
• version control by using @version decorator
• ignore any store node by using @ignore decorator
• support React Native
• support server side rendering (SSR)

Compatibility

mobx-sync-lite	mobx
3.x	5.x

Install

# by yarn
yarn add mobx-sync-lite

# OR by npm
npm i -S mobx-sync-lite

Quick Start

import { AsyncTrunk, date } from 'mobx-sync-lite';
import { observable } from 'mobx';

class Store {
  @observable
  foo = 'bar';

  @date
  @observable
  date = new Date();
}

const store = new Store();

// create a mobx-sync-lite instance, it will:
// 1. load your state from localStorage & ssr rendered state
// 2. persist your store to localStorage automatically
// NOTE: you do not need to call `trunk.updateStore` to persist
// your store, it is persisted automatically!
const trunk = new AsyncTrunk(store, { storage: localStorage });

// init the state and auto persist watcher(use MobX's autorun)
// NOTE: it will load the persisted state first(and must), and
// then load the state from ssr, if you pass it as the first
// argument of `init`, just like trunk.init(__INITIAL_STATE__)
trunk.init().then(() => {
  // you can do any staff now, just like:

  // 1. render app with initial state:
  ReactDOM.render(<App store={store} />);

  // 2. update store, the update of the store will be persisted
  // automatically:
  store.foo = 'foo bar';
});

Full Example

You can see it at example

API Reference

• version control
• ignore control
• custom formatter
• async trunk
• sync trunk
• ssr

version control

Sometimes, if your store's data structure has been changed, which means the persisted data is illegal to use, you can use @version decorator to mark the store node with a version, if the persisted version is different from the declared node's version, the persisted version will be ignored.

For example, we publish an application like the Quick Start at first, and then we want to change the type of Store#foo from string to number. The persisted string value of foo thus become illegal, and should be ignored. It is necessary to use @version to mark the foo field with a new version to omit it:

import { version } from 'mobx-sync-lite';
import { observable } from 'mobx';

class Store {
  @version(1)
  @observable
  foo = 1;

  @date
  @observable
  date = new Date();
}

// ...

When application with the new version is executed, the persisted value of foo will be ignored, while date keeps the persisted value. It means, after calling trunk.init(),the foo becomes 1, and date still stores the previous value.

NOTE: if the new version is strictly different with the persisted version, it will be ignored, or else it will be loaded as normal, so if you use it, we recommend you use an progressive increasing integer to mark it, because you couldn't know the version of persisted in client.

@version also supports class decorator, that means any instance of the class will be ignored if its version is different. For example:

import { version } from 'mobx-sync-lite';
import { observable } from 'mobx';

@version(1)
class C1 {
  p1 = 1;
}

class C2 {
  p2 = 2;
}

class Store {
  c1 = new C1();
  c2 = new C2();
  c1_1 = new C1();
}

If the persisted version of store's c1 && c1_1 has different version with 1, they will be ignored.

NOTE: if you use a non-pure object as the store field, you must initialize it before you call trunk.init, just like custom store class(C1, C2 upon), observable.map, observable.array, etc. And it must be iterable by for..in grammar, if not, you may need to use a custom formatter(see custom formatter bellow) to serialize/de-serialize it.

Signature:

function version(id: number): PropertyDecorator & ClassDecorator;

ignore control

If you hope some fields of your store to skip persisting, just like an article with big size of detailed content. you can use @ignore decorator to mark it, those fields will not be loaded (even if it is persisted in previous version) in the initial, and also the subsequent change will not trigger the action of persisting.

For example: if we want to ignore the date field in Quick Start, we just need to use @ignore to decorate it:

import { date, ignore } from 'mobx-sync-lite';
import { observable } from 'mobx';

class Store {
  @observable
  foo = 'bar';

  @ignore
  @date
  @observable
  date = new Date();
}

@ignore only supports decorating property.

Signature:

/**
 * works in web environment only
 */
function ignore(target: any, key: string): void;
namespace ignore {
  /**
   * works in both web and ssr environment
   */
  function ssr(target: any, key: string): void;

  /**
   * works in ssr environment only
   */
  function ssrOnly(target: any, key: string): void;
}

custom formatter

Sometimes, your store node is not a pure object, just like Set, Map, observable.map<number, Date>, etc, you may need to use custom formatter (@format) to parse/stringify the data/value.

For example, we use Set<Date> as a field:

import { format } from 'mobx-sync-lite';
import { observable } from 'mobx';

class Store {
  @format(
    (data: string[]) => new Set(data.map((d) => new Date(d))),
    (value: Set<Date>) => Array.from(value, (v) => v.toISOString()),
  )
  @observable
  allowDates = new Set<Date>();
}

Built-in formatters:

• @date: parse/stringify date
• @regexp: parse/stringify regexp

Signature:

/**
 * define a custom stringify/parse function for a field, it is useful for
 * builtin objects, just like Date, TypedArray, etc.
 *
 * @example
 *
 * // this example shows how to format a date to timestamp,
 * // and load it from serialized string,
 * // if the date is invalid, it will not be persisted.
 * class SomeStore {
 *   @format<Date, number>(
 *      (timestamp) => new Date(timestamp),
 *      (date) => date ? +date : void 0,
 *   )
 *   dateField = new Date()
 * }
 *
 * @param deserializer - the function to parse the serialized data to
 *      custom object, the first argument is the data serialized by
 *      `serializer`, and the second is the current value of the field.
 * @param serializer - the function to serialize the object to pure js
 *      object or any else could be stringify safely by `JSON.stringify`.
 */
function format<I, O = I>(
  deserializer: (persistedValue: O, currentValue: I) => I,
  serializer?: (value: I) => O,
): PropertyDecorator;

function date(target: any, key: string): void;

function regexp(target: any, key: string): void;

SSR

Sometimes, we hope to use MobX in SSR(Server-Side Rendering), there is no standard way to stringify/load mobx store to/from html template, mobx-sync-lite maybe one.

At first, you need to call config({ ssr: true }) before call any decorator of mobx-sync-lite. And then, you can use JSON.stringify to stringify your state to html template, and then use trunk.init or parseStore to load it to your store.

For example:

// store.ts
import { ignore } from 'mobx-sync-lite'
import { observable } from 'mobx'

export Store {
  @observable userId = 0

  @ignore.ssr
  users = observable.map()
}

// server.ts
import { config } from 'mobx-sync-lite';

config({ ssr: true });

import { Store } from './store';

app.get('/', (_, res) => {
  const store = new Store();

  res.end(`<!DOCTYPE html>
  <html>
  <body>
  <div id=root>${renderToString(<App store={store} />)}</div>
  <script>var __INITIAL_STATE__ = ${JSON.stringify(store).replace(
    /</g,
    '\\u003c',
  )}</script>
  </body>
  </html>`);
});

// client.ts
import { AsyncTrunk } from 'mobx-sync-lite';
import { Store } from './store';

const store = new Store();
const trunk = new AsyncTrunk(store);

trunk.init(__INITIAL_STATE__).then(() => {
  ReactDOM.render(<App store={store} />, document.querySelector('#root'));
});

NOTE: if you do not want to use a trunk to persist/load state from localStorage, just want to use mobx-sync-lite to load SSR state, you can use parseStore(store, state, true) to load it.

For example:

// client.ts
import { parseStore } from 'mobx-sync-lite';
import { Store } from './store';

const store = new Store();

parseStore(store, __INITIAL_STATE__, true);

ReactDOM.render(<App />, document.querySelector('#root'));

Signature:

interface Options {
  ssr: boolean;
}

function config(options: Partial<Options>): void;

function parseStore(store: any, data: any, isFromServer: boolean): void;

async trunk

sync trunk

Both of AsyncTrunk and SyncTrunk is the class to auto load/persist store to storage, the difference between them is the AsyncTrunk runs asynchronously and SyncTrunk runs synchronously.

Signature:

// this is a subset of `Storage`
interface SyncStorage {
  getItem(key: string): string | null;
  setItem(key: string, value: string): void;
  removeItem(key: string): void;
}

// this is a subset of `ReactNative.AsyncStorage`
interface AsyncStorage {
  getItem(key: string): Promise<string | null>;
  setItem(key: string, value: string): Promise<void>;
  removeItem(key: string): Promise<void>;
}

/**
 * sync trunk initial options
 */
export interface SyncTrunkOptions {
  /**
   * storage, SyncStorage only
   * default is localStorage
   */
  storage?: SyncStorage;
  /**
   * the storage key, default is KeyDefaultKey
   */
  storageKey?: string;
  /**
   * the delay time, default is 0
   */
  delay?: number;

  /**
   * error callback
   * @param error
   */
  onError?: (error: any) => void;
}

/**
 * the async trunk initial options
 */
export interface AsyncTrunkOptions {
  /**
   * storage, both AsyncStorage and SyncStorage is supported,
   * default is localStorage
   */
  storage?: AsyncStorage | SyncStorage;
  /**
   * the custom persisted key in storage,
   * default is KeyDefaultKey
   */
  storageKey?: string;
  /**
   * delay milliseconds for run the reaction for mobx,
   * default is 0
   */
  delay?: number;

  /**
   * error callback
   * @param error
   */
  onError?: (error: any) => void;
}

class AsyncTrunk {
  disposer: () => void;
  constructor(store: any, options?: AsyncTrunkOptions);
  init(initialState?: any): Promise<void>;
  // call persist manually
  persist(): Promise<void>;
  // clear persisted state in storage
  clear(): Promise<void>;
  // change the store instance
  updateStore(): Promise<void>;
}

class SyncTrunk {
  disposer: () => void;
  constructor(store: any, options?: SyncTrunkOptions);
  init(initialState?: any): void;
  // call persist manually
  persist(): void;
  // clear persisted state in storage
  clear(): void;
  // change the store instance
  updateStore(): void;
}

License

The MIT License (MIT)

Copyright (c) 2021 thornbill

Copyright (c) 2016-2020 acrazing

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.