Redux Persist
Persist and rehydrate a redux store.
Quickstart
npm install redux-persist
Usage Examples:
- Basic Usage
- Nested Persists
- Hot Module Replacement
- Code Splitting [coming soon]
Basic Usage
Basic usage involves adding persistReducer
and persistStore
to your setup. IMPORTANT Every app needs to decide how many levels of state they want to "merge". The default is 1 level. Please read through the state reconciler docs for more information.
import { createStore } from 'redux'
import { persistStore, persistReducer } from 'redux-persist'
import storage from 'redux-persist/lib/storage'
import rootReducer from './reducers'
const persistConfig = {
key: 'root',
storage,
}
const persistedReducer = persistReducer(persistConfig, rootReducer)
export default () => {
let store = createStore(persistedReducer)
let persistor = persistStore(store)
return { store, persistor }
}
If you are using react, wrap your root component with PersistGate. This delays the rendering of your app's UI until your persisted state has been retrieved and saved to redux. NOTE the PersistGate
loading prop can be null, or any react instance, e.g. loading={<Loading />}
import { PersistGate } from 'redux-persist/integration/react'
const App = () => {
return (
<Provider store={store}>
<PersistGate loading={null} persistor={persistor}>
<RootComponent />
</PersistGate>
</Provider>
);
};
API
Full API
persistReducer(config, reducer)
- arguments
- config object
- required config:
key, storage
- notable other config:
whitelist, blacklist, version, stateReconciler, debug
- reducer function
- any reducer will work, typically this would be the top level reducer returned by
combineReducers
- returns an enhanced reducer
persistStore(store, [config, callback])
- arguments
- store redux store The store to be persisted.
- config object (typically null)
- If you want to avoid that the persistence starts immediately after calling
persistStore
, set the option manualPersist. Example: { manualPersist: true }
Persistence can then be started at any point with peristor.persist()
. You usually want to do this if your storage is not ready when the persistStore
call is made.
- callback function will be called after rehydration is finished.
- returns persistor object
persistor object
- the persistor object is returned by persistStore with the following methods:
.purge()
- purges state from disk and returns a promise
.flush()
- immediately writes all pending state to disk and returns a promise
.pause()
.persist()
State Reconciler
State reconcilers define how incoming state is merged in with initial state. It is critical to choose the right state reconciler for your state. There are three options that ship out of the box, let's look at how each operates:
- hardSet (
import hardSet from 'redux-persist/lib/stateReconciler/hardSet'
)
This will hard set incoming state. This can be desirable in some cases where persistReducer is nested deeper in your reducer tree, or if you do not rely on initialState in your reducer.
- incoming state:
{ foo: incomingFoo }
- initial state:
{ foo: initialFoo, bar: initialBar }
- reconciled state:
{ foo: incomingFoo }
// note bar has been dropped
- autoMergeLevel1 (default)
This will auto merge one level deep. Auto merge means if the some piece of substate was modified by your reducer during the REHYDRATE action, it will skip this piece of state. Level 1 means it will shallow merge 1 level deep.
- incoming state:
{ foo: incomingFoo }
- initial state:
{ foo: initialFoo, bar: initialBar }
- reconciled state:
{ foo: incomingFoo, bar: initialBar }
// note incomingFoo overwrites initialFoo
- autoMergeLevel2 (
import autoMergeLevel2 from 'redux-persist/lib/stateReconciler/autoMergeLevel2'
)
This acts just like autoMergeLevel1, except it shallow merges two levels
- incoming state:
{ foo: incomingFoo }
- initial state:
{ foo: initialFoo, bar: initialBar }
- reconciled state:
{ foo: mergedFoo, bar: initialBar }
// note: initialFoo and incomingFoo are shallow merged
Example
import hardSet from 'redux-persist/lib/stateReconciler/hardSet'
const persistConfig = {
key: 'root',
storage,
stateReconciler: hardSet,
}
React Integration
Redux persist ships with react integration as a convenience. The PersistGate
component is the recommended way to delay rendering until persistence is complete. It works in one of two modes:
loading
prop: The provided loading value will be rendered until persistence is complete at which point children will be rendered.- function children: The function will be invoked with a single
bootstrapped
argument. When bootstrapped is true, persistence is complete and it is safe to render the full app. This can be useful for adding transition animations.
Blacklist & Whitelist
By Example:
const persistConfig = {
key: 'root',
storage: storage,
blacklist: ['navigation']
};
const persistConfig = {
key: 'root',
storage: storage,
whitelist: ['navigation']
};
Nested Persists
Nested persist can be useful for including different storage adapters, code splitting, or deep filtering. For example while blacklist and whitelist only work one level deep, but we can use a nested persist to blacklist a deeper value:
import { combineReducers } from 'redux'
import { persistReducer } from 'redux-persist'
import storage from 'redux-persist/lib/storage'
import { authReducer, otherReducer } from './reducers'
const rootPersistConfig = {
key: 'root',
storage: storage,
blacklist: ['auth']
}
const authPersistConfig = {
key: 'auth',
storage: storage,
blacklist: ['somethingTemporary']
}
const rootReducer = combineReducers({
auth: persistReducer(authPersistConfig, authReducer),
other: otherReducer,
})
export default persistReducer(rootPersistConfig, rootReducer)
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]
Transforms
Transforms allow you to customize the state object that gets persisted and rehydrated.
There are several libraries that tackle some of the common implementations for transforms.
- immutable - support immutable reducers
- seamless-immutable - support seamless-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
- expire-reducer - more flexible alternative to expire transformer above with more options
When the state object gets persisted, it first gets serialized with JSON.stringify()
. If parts of your state object are not mappable to JSON objects, the serialization process may transform these parts of your state in unexpected ways. For example, the javascript Set type does not exist in JSON. When you try to serialize a Set via JSON.stringify()
, it gets converted to an empty object. Probably not what you want.
Below is a Transform that successfully persists a Set property, which simply converts it to an array and back. In this way, the Set gets converted to an Array, which is a recognized data structure in JSON. When pulled out of the persisted store, the array gets converted back to a Set before being saved to the redux store.
import { createTransform } from 'redux-persist';
const SetTransform = createTransform(
(inboundState, key) => {
return { ...inboundState, mySet: [...inboundState.mySet] };
},
(outboundState, key) => {
return { ...outboundState, mySet: new Set(outboundState.mySet) };
},
{ whitelist: ['someReducer'] }
);
export default SetTransform;
The createTransform
function takes three parameters.
- An "inbound" function that gets called right before state is persisted (optional).
- An "outbound" function that gets called right before state is rehydrated (optional).
- A config object that determines which keys in your state will be transformed (by default no keys are transformed).
In order to take effect transforms need to be added to a PersistReducer
’s config object.
import storage from 'redux-persist/lib/storage';
import { SetTransform } from './transforms';
const persistConfig = {
key: 'root',
storage: storage,
transforms: [SetTransform]
};
Storage Engines
- localStorage
import storage from 'redux-persist/lib/storage'
- sessionStorage
import storageSession from 'redux-persist/lib/storage/session'
- AsyncStorage react-native
import AsyncStorage from '@react-native-community/async-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-info).
- redux-persist-expo-filesystem react-native, similar to redux-persist-filesystem-storage but does not require linking or ejecting CRNA/Expo app. Only available if using Expo SDK (Expo, create-react-native-app, standalone).
- redux-persist-expo-securestore react-native, for sensitive information using Expo's SecureStore. Only available if using Expo SDK (Expo, create-react-native-app, standalone).
- redux-persist-fs-storage react-native-fs engine
- redux-persist-cookie-storage Cookie storage engine, works in browser and Node.js, for universal / isomorphic apps
- redux-persist-weapp-storage Storage engine for wechat mini program, also compatible with wepy
- redux-persist-webextension-storage Storage engine for browser (Chrome, Firefox) web extension storage
- @bankify/redux-persist-realm Storage engine for Realm database, you will need to install Realm first
- redux-persist-pouchdb Storage engine for PouchDB.
- custom any conforming storage api implementing the following methods:
setItem
getItem
removeItem
. (NB: These methods must support promises)
Chat Room
#redux-persist channel in the Reactiflux Discord
Blog articles from the community