๐ง AsyncStorage
Deprecated. Use @react-native-community/async-storage instead.
AsyncStorage
is an unencrypted, asynchronous, persistent, key-value storage system that is global to the app. It should be used instead of LocalStorage.
It is recommended that you use an abstraction on top of AsyncStorage
instead of AsyncStorage
directly for anything more than light usage since it operates globally.
On iOS, AsyncStorage
is backed by native code that stores small values in a serialized dictionary and larger values in separate files. On Android, AsyncStorage
will use either RocksDB or SQLite based on what is available.
The AsyncStorage
JavaScript code is a facade that provides a clear JavaScript API, real Error
objects, and non-multi functions. Each method in the API returns a Promise
object.
Importing the AsyncStorage
library:
import { AsyncStorage } from 'react-native';
Persisting data:
_storeData = async () => { try { await AsyncStorage.setItem( '@MySuperStore:key', 'I like to save it.' ); } catch (error) { // Error saving data }};
Fetching data:
_retrieveData = async () => { try { const value = await AsyncStorage.getItem('TASKS'); if (value !== null) { // We have data!! console.log(value); } } catch (error) { // Error retrieving data }};
Reference
#
MethodsgetItem()
#
static getItem(key: string, [callback]: ?(error: ?Error, result: ?string) => void)
Fetches an item for a key
and invokes a callback upon completion. Returns a Promise
object.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
key | string | Yes | Key of the item to fetch. |
callback | ?(error: ?Error, result: ?string) => void | No | Function that will be called with a result if found or any error. |
setItem()
#
static setItem(key: string, value: string, [callback]: ?(error: ?Error) => void)
Sets the value for a key
and invokes a callback upon completion. Returns a Promise
object.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
key | string | Yes | Key of the item to set. |
value | string | Yes | Value to set for the key . |
callback | ?(error: ?Error) => void | No | Function that will be called with any error. |
removeItem()
#
static removeItem(key: string, [callback]: ?(error: ?Error) => void)
Removes an item for a key
and invokes a callback upon completion. Returns a Promise
object.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
key | string | Yes | Key of the item to remove. |
callback | ?(error: ?Error) => void | No | Function that will be called with any error. |
mergeItem()
#
static mergeItem(key: string, value: string, [callback]: ?(error: ?Error) => void)
Merges an existing key
value with an input value, assuming both values are stringified JSON. Returns a Promise
object.
NOTE: This is not supported by all native implementations.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
key | string | Yes | Key of the item to modify. |
value | string | Yes | New value to merge for the key . |
callback | ?(error: ?Error) => void | No | Function that will be called with any error. |
Example:
let UID123_object = { name: 'Chris', age: 30, traits: { hair: 'brown', eyes: 'brown' }};// You only need to define what will be added or updatedlet UID123_delta = { age: 31, traits: { eyes: 'blue', shoe_size: 10 }};
AsyncStorage.setItem( 'UID123', JSON.stringify(UID123_object), () => { AsyncStorage.mergeItem( 'UID123', JSON.stringify(UID123_delta), () => { AsyncStorage.getItem('UID123', (err, result) => { console.log(result); }); } ); });
// Console log result:// => {'name':'Chris','age':31,'traits':// {'shoe_size':10,'hair':'brown','eyes':'blue'}}
clear()
#
static clear([callback]: ?(error: ?Error) => void)
Erases all AsyncStorage
for all clients, libraries, etc. You probably don't want to call this; use removeItem
or multiRemove
to clear only your app's keys. Returns a Promise
object.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
callback | ?(error: ?Error) => void | No | Function that will be called with any error. |
getAllKeys()
#
static getAllKeys([callback]: ?(error: ?Error, keys: ?Array<string>) => void)
Gets all keys known to your app; for all callers, libraries, etc. Returns a Promise
object.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
callback | ?(error: ?Error, keys: ?Array<string>) => void | No | Function that will be called with all keys found and any error. |
flushGetRequests()
#
static flushGetRequests(): [object Object]
Flushes any pending requests using a single batch call to get the data.
multiGet()
#
static multiGet(keys: Array<string>, [callback]: ?(errors: ?Array<Error>, result: ?Array<Array <string>>) => void)
This allows you to batch the fetching of items given an array of key
inputs. Your callback will be invoked with an array of corresponding key-value pairs found:
multiGet(['k1', 'k2'], cb) -> cb([['k1', 'val1'], ['k2', 'val2']])
The method returns a Promise
object.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
keys | Array<string> | Yes | Array of key for the items to get. |
callback | ?(errors: ?Array<Error>, result: ?Array<Array<string>>) => void | No | Function that will be called with a key-value array of the results, plus an array of any key-specific errors found. |
Example:
AsyncStorage.getAllKeys((err, keys) => { AsyncStorage.multiGet(keys, (err, stores) => { stores.map((result, i, store) => { // get at each store's key/value so you can work with it let key = store[i][0]; let value = store[i][1]; }); });});
multiSet()
#
static multiSet(keyValuePairs: Array<Array <string>>, [callback]: ?(errors: ?Array<Error>) => void)
Use this as a batch operation for storing multiple key-value pairs. When the operation completes you'll get a single callback with any errors:
multiSet([['k1', 'val1'], ['k2', 'val2']], cb);
The method returns a Promise
object.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
keyValuePairs | Array<Array<string>> | Yes | Array of key-value array for the items to set. |
callback | ?(errors: ?Array<Error>) => void | No | Function that will be called with an array of any key-specific errors found. |
multiRemove()
#
static multiRemove(keys: Array<string>, [callback]: ?(errors: ?Array<Error>) => void)
Call this to batch the deletion of all keys in the keys
array. Returns a Promise
object.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
keys | Array<string> | Yes | Array of key for the items to delete. |
callback | ?(errors: ?Array<Error>) => void | No | Function that will be called an array of any key-specific errors found. |
Example:
let keys = ['k1', 'k2'];AsyncStorage.multiRemove(keys, (err) => { // keys k1 & k2 removed, if they existed // do most stuff after removal (if you want)});
multiMerge()
#
static multiMerge(keyValuePairs: Array<Array <string>>, [callback]: ?(errors: ?Array<Error>) => void)
Batch operation to merge in existing and new values for a given set of keys. This assumes that the values are stringified JSON. Returns a Promise
object.
NOTE: This is not supported by all native implementations.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
keyValuePairs | Array<Array<string>> | Yes | Array of key-value array for the items to merge. |
callback | ?(errors: ?Array<Error>) => void | No | Function that will be called with an array of any key-specific errors found. |
Example:
// first user, initial valueslet UID234_object = { name: 'Chris', age: 30, traits: { hair: 'brown', eyes: 'brown' }};
// first user, delta valueslet UID234_delta = { age: 31, traits: { eyes: 'blue', shoe_size: 10 }};
// second user, initial valueslet UID345_object = { name: 'Marge', age: 25, traits: { hair: 'blonde', eyes: 'blue' }};
// second user, delta valueslet UID345_delta = { age: 26, traits: { eyes: 'green', shoe_size: 6 }};
let multi_set_pairs = [ ['UID234', JSON.stringify(UID234_object)], ['UID345', JSON.stringify(UID345_object)]];let multi_merge_pairs = [ ['UID234', JSON.stringify(UID234_delta)], ['UID345', JSON.stringify(UID345_delta)]];
AsyncStorage.multiSet(multi_set_pairs, (err) => { AsyncStorage.multiMerge(multi_merge_pairs, (err) => { AsyncStorage.multiGet(['UID234', 'UID345'], (err, stores) => { stores.map((result, i, store) => { let key = store[i][0]; let val = store[i][1]; console.log(key, val); }); }); });});
// Console log results:// => UID234 {"name":"Chris","age":31,"traits":{"shoe_size":10,"hair":"brown","eyes":"blue"}}// => UID345 {"name":"Marge","age":26,"traits":{"shoe_size":6,"hair":"blonde","eyes":"green"}}