AsyncStorage implementation issue.

[dezudas]

will it be possible to provide an example for AsyncStorage when I tried it says "Possible Unhandled Promise Rejection (id: 0):
TypeError: Cannot read property 'hasOwnProperty' of null"

[deargosep]

same here

[fervailanti]

Same here, any solution?

[fagerbua]

You don't need to use this library to get simple persistence with Recoil and React Native. Just adapt the localForage example from the Recoil documentation, and you get (with TypeScript):

import {atom, AtomEffect, DefaultValue} from "recoil";

function persistAtom<T>(key: string): AtomEffect<T> {
  return ({setSelf, onSet}) => {
    setSelf(AsyncStorage.getItem(key).then(savedValue =>
      savedValue != null
        ? JSON.parse(savedValue)
        : new DefaultValue() // Abort initialization if no value was stored
    ));

    // Subscribe to state changes and persist them to localForage
    onSet((newValue, _, isReset) => {
      isReset
        ? AsyncStorage.removeItem(key)
        : AsyncStorage.setItem(key, JSON.stringify(newValue));
    });
  };
}

const myAtom =  atom({key: 'my-key', default: {}, effects_UNSTABLE: [persistAtom('my-async-storage-key')]})

Then wrap your RecoilRoot with a Suspense component:

      <React.Suspense fallback={<View><Text>Loading</Text></View>}>
        <RecoilRoot>
          {/* your app components */}
        </RecoilRoot>
      </React.Suspense>

[cuzzlor]

Despite the typings, it doesn't seem to support async getItem or setItem.

[ipoogleduck]

I had to adapt the code from @fagerbua cause I was getting blank screens. This worked better for me, copying the latest recoil documentation:

function persistAtom<T>(key: string): AtomEffect<T> {
    return ({ setSelf, onSet, trigger }) => {
        const loadPersisted = async () => {
            const savedValue = await AsyncStorage.getItem(key);

            if (savedValue != null) {
                setSelf(JSON.parse(savedValue));
            }
        };

        // Asynchronously set the persisted data
        if (trigger === 'get') {
            loadPersisted();
        }

        // Subscribe to state changes and persist them to localForage
        onSet((newValue, _, isReset) => {
            isReset
                ? AsyncStorage.removeItem(key)
                : AsyncStorage.setItem(key, JSON.stringify(newValue));
        })
    }
}

const myAtom =  atom({key: 'my-key', default: {}, effects_UNSTABLE: [persistAtom('my-async-storage-key')]})