redux-persist

What is redux-persist?

redux-persist is a library that allows you to save the Redux store in persistent storage, such as local storage, session storage, or even custom storage engines. This helps in maintaining the state of the application across page reloads.

What are redux-persist's main functionalities?

Persisting Redux State

This feature allows you to persist the Redux state using a storage engine like local storage. The `persistReducer` function wraps your root reducer, and `persistStore` initializes the persistor.

const persistConfig = { key: 'root', storage }; const persistedReducer = persistReducer(persistConfig, rootReducer); const store = createStore(persistedReducer); const persistor = persistStore(store);

Rehydrating State

Rehydration is the process of loading the persisted state back into the Redux store when the application starts. This ensures that the state is restored to its previous state before the page was reloaded.

persistStore(store, null, () => { console.log('Rehydration complete'); });

Custom Storage Engines

You can use custom storage engines if the default local storage or session storage does not meet your requirements. This example shows how to create a noop storage engine for environments where local storage is not available.

import createWebStorage from 'redux-persist/lib/storage/createWebStorage'; const createNoopStorage = () => { return { getItem(_key) { return Promise.resolve(null); }, setItem(_key, value) { return Promise.resolve(value); }, removeItem(_key) { return Promise.resolve(); } }; }; const storage = typeof window !== 'undefined' ? createWebStorage('local') : createNoopStorage();

Other packages similar to redux-persist

redux-localstorage

redux-localstorage is another library that allows you to persist Redux state to local storage. It is similar to redux-persist but offers a more modular approach, allowing you to choose different storage adapters and serializers.

redux-persist-transform-encrypt

redux-persist-transform-encrypt is a transformer for redux-persist that encrypts your persisted state. This is useful if you need to store sensitive information securely. It works as an add-on to redux-persist, providing encryption capabilities.

redux-persist-cookie-storage

redux-persist-cookie-storage is a storage engine for redux-persist that uses cookies instead of local storage or session storage. This can be useful for server-side rendering or when you need to share state across different subdomains.

README

Redux Persist

Persist and rehydrate a redux store.

Redux Persist is performant, easy to implement, and easy to extend.

npm i redux-persist

Note: These docs apply to redux-persist v5. v4 will be supported for the forseeable future, and if it works well for your use case you are encouraged to stay on v4.

Usage

API Docs

import { persistStore, persistCombineReducers } from 'redux-persist'
import storage from 'redux-persist/es/storage' // default: localStorage if web, AsyncStorage if react-native
import reducers from './reducers' // where reducers is a object of reducers

const config = {
  key: 'root',
  storage,
}

const reducer = persistCombineReducers(config, reducers)

function configureStore () {
  // ...
  let store = createStore(reducer)
  let persistor = persistStore(store)
  
  return { persistor, store }
}

Additionally if you are using react, it is recommended you use the provided PersistGate component for integration. This will take care of delaying the rendering of the app until rehydration is complete.

class App extends Component {
  //...
  render() {
    return (
      <PersistGate persistor={persistor}>
        {/* rest of app */}
      </PersistGate>
    )
  }
}

Additional Usage Examples:

1. Nested Persists
2. Code Splitting [coming soon]
3. Hot Module Reloading [coming soon]

v5 Breaking Changes

There are three important breaking changes.

1. api has changed as described in the above migration section
2. state with cycles is no longer serialized using json-stringify-safe, and will instead noop.
3. state methods can no longer be overridden which means all top level state needs to be plain objects. redux-persist-transform-immutable will continue to operate as before as it works on substate, not top level state.

Additionally v5 does not yet have typescript bindings.

Migration from v4 to v5

WARNING v4 stored state is not compatible with v5. If you upgrade a v4 application, your users will lose their stored state upon upgrade. You can try the (highly) experimental v4 -> v5 state migration if you please. Feedback appreciated.

Standard Usage:

• remove autoRehydrate
• changes to persistStore:
  • 1. remove config argument (or replace with an empty object)
  • 1. remove all arguments from the callback. If you need state you can call store.getState()
  • 1. All constants (ex: {REHYDRATE, PURGE}) has moved to redux-persist/lib/constants instead of redux-persist/constants
• replace combineReducers with persistCombineReducers
  • e.g. let reducer = persistCombineReducers(config, reducers)
• changes to config:
  • key is now required. Can be set to anything, e.g. 'primary'
  • storage is now required. For default storage: import storage from 'redux-persist/lib/storage'

Recommended Additions

• use new PersistGate to delay rendering until rehydration is complete
  • import { PersistGate } from 'redux-persist/lib/integration/react'
• set config.debug = true to get useful logging

If your implementatation uses getStoredState + createPersistor see alternate migration

Why v5

Long story short, the changes are required in order to support new use cases

• code splitting reducers
• easier to ship persist support inside of other libs (e.g. redux-offline)
• ability to colocate persistence rules with the reducer it pertains to
• first class migration support
• enable PersistGate react component which blocks rendering until persistence is complete (and enables similar patterns for integration)
• possible to nest persistence
• gaurantee consistent state atoms
• better debugability and extensibility

Migrations

persistReducer has a general purpose "migrate" config which will be called after getting stored state but before actually reconciling with the reducer. It can be any function which takes state as an argument and returns a promise to return a new state object.

Redux Persist ships with createMigrate, which helps create a synchronous migration for moving from any version of stored state to the current state version. [Additional information]

Nested Persists

Persistence can now be nested, allowing for multiple persistoids with differing configuration to easily coexist.

import { combineReducers } from 'redux' 
import { persistReducer } from 'redux-persist'
import session from 'redux-persist/lib/storage/session'
import localForage from 'localforage'

import { fooReducer, barReducer } from './reducers'

// foo state to be stored in localForage, but lets not persist someEmphemeralKey
const fooPersistConfig = {
  key: 'foo',
  storage: localForage,
  blacklist: ['someEphemeralKey'],
}

// bar state should only last for the tab session
const barPersistConfig = {
  key: 'bar',
  storage: session,
}

let rootReducer = combineReducers({
  foo: persistReducer(fooPersistConfig, fooReducer),
  bar: persistReducer(barPersistConfig, barReducer),
})

Additionally depending on the mount point of persistReducer, you may not want to reconcile state at all.

import { hardSet } from 'redux-persist/lib/stateReconciler/hardSet'

//...

const fooConfig = {
  key: 'foo',
  storage: localForage,
  stateReconciler: hardSet,
}

let reducer = combineReducer({
  foo: persistReducer(fooConfig, fooReducer)
})

Experimental v4 to v5 State Migration

• warning: this method is completely untested
• v5 getStoredState is not compatible with v4, so by default v5 will cause all of the persisted state from v4 to disappear on first run
• v5 ships with an experimental v4 -> v5 migration that works by overriding the default getStoredState implementation Warning this is completely untested, please try and report back with any issues.

import getStoredStateMigrateV4 from 'redux-persist/lib/integration/getStoredStateMigratev4'
// ...
persistReducer({
  // ...
  getStoredState: getStoredStateMigrateV4(yourOldV4Config)
}, baseReducer)

Storage Engines

• localStorage import storage from 'redux-persist/lib/storage'
• sessionStorage import sessionStorage from 'redux-persist/lib/storage/session'
• AsyncStorage react-native import storage from 'redux-persist/lib/storage'
• localForage recommended for web
• electron storage Electron support via electron store
• redux-persist-filesystem-storage react-native, to mitigate storage size limitations in android (#199, #284)
• redux-persist-node-storage for use in nodejs environments.
• redux-persist-sensitive-storage react-native, for sensitive information (uses react-native-sensitive-storage).
• redux-persist-fs-storage react-native-fs engine
• custom any conforming storage api implementing the following methods: setItem getItem removeItem. (NB: These methods must support promises)

Transforms

Transforms allow for arbitrary state transforms before saving and during rehydration.

• immutable - support immutable reducers
• compress - compress your serialized state with lz-string
• encrypt - encrypt your serialized state with AES
• filter - store or load a subset of your state
• filter-immutable - store or load a subset of your state with support for immutablejs
• expire - expire a specific subset of your state based on a property
• custom transforms:

import { createTransform, persistReducer } from 'redux-persist'

let myTransform = createTransform(
  // transform state coming from redux on its way to being serialized and stored
  (state, key) => specialSerialize(state, key),
  // transform state coming from storage, on its way to be rehydrated into redux
  (state, key) => specialDeserialize(state, key),
  // configuration options
  {whitelist: ['specialKey']}
)

const reducer = persistReducer({transforms: [myTransform]}, baseReducer)