Putting Async functions into useEffect() hook in React

Question

I'm finishing up an app in which I want to hide my GoogleMap API key behind my secure API. My intention is to call for the API key once I verify that I have an authenticated user. The problem is that between the async calls, changes are not reflected with the state change.

This is what I am doing:

export default function App() {
  const [dateRange, setDateRange] = useState(initialDateRange);
  const [formState, updateFormState] = useState(initialFormState);
  const [user, setUser] = useState(null);
  const [googleApiKey, setGoogleApiKey] = useState(null);

  useEffect(() => {
    async function updateAuth() {
      try {
        await checkUser();
        await getGoogleApiKey();
        await setAuthListener();
      } catch (error) {}
    }
    updateAuth();
  }, []);

  async function checkUser() {
    try {
      const user = await Auth.currentAuthenticatedUser();
      setUser(user);
      if (user !== authenticatedUser) {
        updateFormState(() => ({
          ...formState,
          authenticatedUser: user
        }));
      }
    } catch (error) {
      console.log(error);
    }
  }

  async function getGoogleApiKey() {
    const googleApiUrl = `${process.env.REACT_APP_API_PATH}apikey?googleapikey=true`; 
    try {
      console.log('USER_USER_USER', user);
      const apiKey = await fetch(googleApiUrl, {
        method: 'GET',
        headers: {
          'Content-Type': 'application/json',
          Authorization: user.signInUserSession.idToken.jwtToken
        }
      });
      console.log('GOT_GOOGLE_API_KEY', apiKey);
      setGoogleApiKey(apiKey);
    } catch (error) {
      console.log(error);
    }
  }

  async function setAuthListener() {
    Hub.listen('auth', (data) => {
      const event = data.payload.event;
      switch (data.payload.event) {
        case 'signOut':
          console.log('signing out...');
          console.log(event);
          updateFormState(() => ({
            ...formState,
            username: '',
            password: '',
            email: '',
            authenticatedUser: null
          }));
          break;
        default:
          break;
      }
    });
  }

But I am getting the error:

USER_USER_USER null
App.js:78 TypeError: Cannot read property 'signInUserSession' of null
    at getGoogleApiKey (App.js:72)
    at updateAuth (App.js:42)

If this is the wrong paradigm, I'd appreciate any alternatives!

Yuan-Hao Chiang · Accepted Answer · 2020-10-04 03:01:56Z

4

When setUser is called, the user variable still holds old user information (null in this case), regardless of async/await:

await checkUser();        // setUser(something) will not happen until next run
await getGoogleApiKey();  // user is still null
await setAuthListener();

One other choice would be to add another effect when user changes:

useEffect(() => {
  if (user) {
     getGoogleApiKey();
  }
}, [user]);

Or, call getGoogleApiKey with the parameter:

const user = await checkUser(); // return user
await getGoogleApiKey(user);
await setAuthListener();

Since the logic gets complex, I would suggest trying the useReducer hook because dispatch simplifies this complex back and forth scenarios.

edited Oct 4, 2020 at 3:01

answered Oct 4, 2020 at 1:33

Yuan-Hao Chiang

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1 Comment

Jim from Princeton Over a year ago

I used const user = await checkUser(); // return user and it worked... pushing the key down to the Map components and rendering them conditionally if the api key is not null. Thanks!

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