useAsyncStorage custom hook with useState hook in React Native

user_2049234 0
Viewed 4018

As we know, we cannot use LocalStorage in React Native. I try to create a useAsyncStorage custom hook instead, which do same function as LocalStorage custome hook in react to store the data in mobile device's local storage.

useAsyncStorage.js

import React, { useEffect, useState } from 'react';
import AsyncStorage from '@react-native-community/async-storage';


export default function useAsyncStorage(key, defaultValue) {
  const [storageValue, updateStorageValue] = useState(defaultValue);

  useEffect(() => {
    getStorageValue();
  }, []);

  async function getStorageValue() {
    let value = defaultValue;
    try {
      value = (JSON.parse(await AsyncStorage.getItem(key))) || defaultValue;
    } catch (e) {
      // handle here
    } finally {
      updateStorage(value);
    }
  }

  async function updateStorage(newValue) {
    try {
      await AsyncStorage.setItem(key, JSON.stringify(newValue));
    } catch (e) {
      // handle here
    } finally {
      getStorageValue();
    }
  }

  return [storageValue, updateStorageValue];
}

In App.js I import useAsyncStorage.js and try use it to store the data in mobile device's local storage.

import useAsyncStorage from './useAsyncStorage';

To initial it:

const [userLevel, setUserLevel] = useAsyncStorage("userLevel",1)

To setValue:

 setUserLevel(prevLevel => {
   return prevLevel + 1
 })

It works as expected and set the data, but it cannot retrieve data from AsyncStorage after app reload.

Could anyone please help? Did I do something wrong in useAsyncStorage custom hook? Why data don't store in AsyncStorage?

asyncstorage react-native react-hooks reactjs javascript
4 Answers

You can try this custom hook that I made

import { useEffect, useState } from 'react'
import AsyncStorage from '@react-native-async-storage/async-storage'

const useAsyncStorage = (key, initialValue) => {
  const [data, setData] = useState(initialValue)
  const [retrivedFromStorage, setRetrievedFromStorage] = useState(false)

  useEffect(() => {
    ;(async () => {
      try {
        const value = await AsyncStorage.getItem(key)
        setData(JSON.parse(value) || initialValue)
        setRetrievedFromStorage(true)
      } catch (error) {
        console.error('useAsyncStorage getItem error:', error)
      }
    })()
  }, [key, initialValue])

  const setNewData = async (value) => {
    try {
      await AsyncStorage.setItem(key, JSON.stringify(value))
      setData(value)
    } catch (error) {
      console.error('useAsyncStorage setItem error:', error)
    }
  }

  return [data, setNewData, retrivedFromStorage]
}
export default useAsyncStorage

you can also use the retrievedFromStorage to check if the data was successfully retrieved from the AsyncStorage.

user_147608200

This useAsyncStorage implementation is working for me.

function useAsyncStorage(key, initialValue) {
  const [storedValue, setStoredValue] = useState();

  async function getStoredItem(key, initialValue) {
    try {
      const item = await AsyncStorage.getItem(key);
      const value = item ? JSON.parse(item) : initialValue;
      setStoredValue(value);
    } catch (error) {
      console.log(error);
    }
  }

  useEffect(() => {
    getStoredItem(key, initialValue);
  }, [key, initialValue]);

  const setValue = async (value) => {
    try {
      const valueToStore =
        value instanceof Function ? value(storedValue) : value;
      setStoredValue(valueToStore);
      await AsyncStorage.setItem(key, JSON.stringify(valueToStore));
    } catch (error) {
      console.log(error);
    }
  };

  return [storedValue, setValue];
}

Link to demo Snack:

https://snack.expo.io/@yajana/useasyncstorage

Reference:

https://usehooks.com/useLocalStorage/

Other similar implementation:

https://github.com/react-native-hooks/async-storage/blob/master/src/index.js

user_85919950

I found this one works for me.

import { useEffect, useState } from 'react';
import AsyncStorage from '@react-native-community/async-storage';

export default function useAsyncStorage(key, initialValue) {
  const [storedValue, setStoredValue] = useState(initialValue);
  useEffect(() => {
    AsyncStorage.getItem(key)
      .then(value => {
        if (value === null) return initialValue;
        return JSON.parse(value);
      })
      .then(setStoredValue)
  }, [key, initialValue]);

  const setValue = value => {
    const valueToStore = value instanceof Function ? value(storedValue) : value;
    setStoredValue(valueToStore);
    AsyncStorage.setItem(key, JSON.stringify(valueToStore));
  }

  return [storedValue, setValue];
}

Reference: https://gist.github.com/msukmanowsky/08a3650223dda8b102d2c9fe94ad5c12

user_20492340

My implementation of useAsyncStorage hook with TypeScript:

const useAsyncStorage = (key: string) => {
  const [storedData, setStoredData] = useState("");

  const storeData = async (value: string | object) => {
    try {
      const valueToStore =
        typeof value === "string" ? value : JSON.stringify(value);
      await AsyncStorage.setItem(key, valueToStore);
      setStoredData(valueToStore);
    } catch (e) {
      console.error(e);
    }
  };

  useEffect(() => {
    const getData = async () => {
      try {
        const storageValue = await AsyncStorage.getItem(key);
        if (storageValue !== null) {
          setStoredData(storageValue);
        }
      } catch (e) {
        console.error(e);
      }
    };
    getData();
  }, [key]);

  return { storedData, storeData };
};
user_118382350
Related