How can I export a variable to AsyncStorage?

Question

I want to export my user_id variable from authActions.js to USER_KEY const from auth.js Is that possible?

here is my authActions.js function where generates user_id

export function loginUser(email, password) {
  return function (dispatch) {
    return axios.post(SIGNIN_URL, { email, password }).then((response) => {
      var { user_id, token } = response.data;
      console.log('my user_id = ' + user_id);
      console.log('my token = ' + token);
      dispatch(authUser(user_id));
      isSignedIn();
    }).catch((error) => {
      console.log(error);
      dispatch(addAlert("Could not log in."));
    });
  };
}

and here is my auth.js where I have the const USER_KEY

import { AsyncStorage } from "react-native";

export const USER_KEY = "auth-key";
console.log('USER_KEY ' + USER_KEY);

export const onSignIn = () => AsyncStorage.setItem(USER_KEY, "true");
export const onSignOut = () => AsyncStorage.removeItem(USER_KEY);

export const isSignedIn = () => {
  return new Promise((resolve, reject) => {
    AsyncStorage.getItem(USER_KEY)
      .then(res => {
        if (res !== null) {
          resolve(true);
        } else {
          resolve(false);
        }
      })
      .catch(err => reject(err));
  });
};

Answer 1

Change:

export const onSignIn = () => AsyncStorage.setItem(USER_KEY, "true");

to:

export const onSignIn = (user_id) => AsyncStorage.setItem(USER_KEY, user_id);

And then in the .then() of your POST, you can do:

onSignIn(user_id);

But then checking isSignedIn() immediately after probably won't work as expected, since AsyncStorage is asynchronous. If they have just gotten a user_id and token, is it necessary to check right there?