React - Load component after useContext returns value

user_9522864 0
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So I have Dashboard component which should display currentUsers info. I keep my currentUser in global context/state.

The problem is when Dashboard component renders FIRST time currentUser is null even tho user is actually logged in. Because of that I get null error at line 14 or if I comment dashboard states the if statement on line 22 will happen and it will redirect me even if user is logged in.

Is there a way to await for isLoggedInFunction to finish and then do the logic in Dashboard component?

Dashboard component

In App.js

export const CurrentUserContext = React.createContext(null); // Global Context
const [currentUser, setCurrentUser] = useState(null); // Global State


// Setting current user
useEffect(() => {
    setCurrentUser(isLoggedIn()).catch(err => console.log(err));
}, []);


// IsLoggedIn Method
export function isLoggedIn() {
     return localStorage.getItem('user') === null ? 
          null : 
          JSON.parse(localStorage.getItem('user'));
}


<CurrentUserContext.Provider value={{ currentUser, setCurrentUser }}> // Provider
react-hooks reactjs state asynchronous
2 Answers

You can set the default value for the user to avoid the first error.

In this case you can change your Dashboard like this:

/* ... */

const {
    currentUser = {
        isLoggedIn: false,
        firstName: 'first name'
    }
} = useContext(CurrentUserContext);

const [firstName, setFirstName] = useState(currentUser.firstName);
/* ... */

if (!currentUser.isLoggedIn) {
    return <Redirect to={'/login'}/>;
}

/* ... */

To solve the second problem, you need to check if your localStorage actually contains the user field after authorization.

user_165932750

I fixed both problems by doing this.

const [currentUser, setCurrentUser] = useState(null); // Replaced this line with next line
const [currentUser, setCurrentUser] = useState(() => isLoggedIn());

And I removed useeffect since I don't need it anymore.

// Setting current user
useEffect(() => {
  setCurrentUser(isLoggedIn()).catch(err => console.log(err));
}, []);
user_95228640
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