react-nativemobxmobx-state-tree

How to Persist Mobx State Tree in React Native?


I need to persist a MST Store in React Native. The data is changed seldomly.

I'm confused between using AsyncStorage and AutoRun.


Solution

  • For persisting MST stores, you might be interested in using mst-persist, which, per the README, is currently a small wrapper around MST's onSnapshot and applySnapshot (disclaimer: I'm the creator).

    To persist data in React Native with mst-persist backed by AsyncStorage, one would do:

    import { types } from 'mobx-state-tree'
    import { AsyncStorage } from 'react-native'
    import { persist } from 'mst-persist'
    
    const SomeStore = types.model('Store', {
      name: 'John Doe',
      age: 32
    })
    
    const someStore = SomeStore.create()
    
    persist('some', someStore, {
      storage: AsyncStorage,  // default: localStorage
      jsonify: true  // if you use AsyncStorage, this should be true
                      // default: true
      whitelist: ['name']  // only these keys will be persisted
    }).then(() => console.log('someStore has been hydrated'))
    

    My original use case for mst-persist was for React Native and the current README will actually point you to a commit in an OSS RN manga reader app I made as an example.

    If you're interested in how to do it with MST without another library like mst-persist, the persistence source code is actually < 50 LoC currently. And minus some features, it's a brisk < 20 LoC:

    import { onSnapshot, applySnapshot } from 'mobx-state-tree'
    
    export const persist = (name, store, options = {}) => {
      let {storage, jsonify} = options
    
      onSnapshot(store, (_snapshot) => {
        const snapshot = { ..._snapshot }
        const data = !jsonify ? snapshot : JSON.stringify(snapshot)
        storage.setItem(name, data)
      })
    
      return storage.getItem(name)
        .then((data) => {
          const snapshot = !jsonify ? data : JSON.parse(data)
          applySnapshot(store, snapshot)
        })
    }
    

    There are a handful of other examples out in the wild that show similar functionality as well, such as this gist that mst-persist is partly inspired by, this repo that uses HoCs and PersistGates similar to redux-persist, and this gist that takes multiple stores as an argument.