We Keep Coding

Prevent Router from Loading Page Briefly before Redirect

I have a session context for my NextJS application where anyone accessing /app/ directory pages have to go through an authorization check prior to allowing the user to access the page.
While my logic works in redirecting users without proper authentication, it is a bit glitchy because when someone navigate to the URL, /app/profile/ the page briefly loads before being redirected by Router.
I am wondering what is the best way to have this check happen prior to router loading the unauthorized page and redirecting them to the /login/ page.
Here are the steps in the authorization check:
Check is the user object has a property, authorized
Query the server for a session token
if the object from the server request comes back with authorized = false, then redirect user to /login/
Here is the code:
import React, { createContext, useContext, useEffect, useState } from 'react'
import { useRouter } from 'next/router'
import axios from 'axios'
export const SessionContext = createContext(null);
const AppSession = ({ children }) => {
const router = useRouter()
const routerPath = router.pathname;
const [user, setUser] = useState({ user_id: '', user_email: '', user_avatar: ''})
useEffect(()=> {
// Check for populated user state if pages are accessed with the path /app/
if (routerPath.includes("/app/")){
if (user){
if(user.authenticated === undefined){
// Check if user session exists
axios.get('/api/auth/session/')
.then(res => {
const data = res.data;
// Update user state depending on the data returned
setUser(data)
// If user session does not exist, redirect to /login/
if (data.authenticated === false){
router.push('/login/')
}
})
.catch(err => {
console.log(err)
});
}
}
}
}, [])
return (
<SessionContext.Provider value={{user, setUser}}>
{children}
</SessionContext.Provider>
)
}
export const getUserState = () => {
const { user } = useContext(SessionContext)
return user;
}
export const updateUserState = () => {
const { setUser } = useContext(SessionContext)
return (user) => {
setUser(user);
}
}
export default AppSession;

Since user.authenticated isn't defined in the initial user state you can conditionally render null or some loading indicator while user.authenticated is undefined. Once user.authenticated is defined the code should either redirect to "/login" or render the SessionContext.Provider component.
Example:
const AppSession = ({ children }) => {
const router = useRouter();
const routerPath = router.pathname;
const [user, setUser] = useState({ user_id: '', user_email: '', user_avatar: ''});
...
if (user.authenticated === undefined) {
return null; // or loading indicator/spinner/etc
}
return (
<SessionContext.Provider value={{ user, setUser }}>
{children}
</SessionContext.Provider>
);
};

Check out getServerSideProps, redirects in getServerSideProps and this article.
In your client-side, if you export the NextJS function definition named getServerSideProps from a page, NextJS pre-renders the page on each request using the data returned by getServerSideProps.
In other words, you can use getServerSideProps to retrieve and check the user while pre-rendering the page and then choose to redirect instead of render if your condition is not met.
Here is an example.
function Page({ data }) {
// Render data...
}
export async function getServerSideProps(context) {
const { req, res } = context;
try {
// get your user
if (user.authenticated === undefined) {
return {
redirect: {
permanent: false,
destination: `/`,
},
};
}
return {
props: {
// any static props you want to deliver to the component
},
};
} catch (e) {
console.error("uh oh");
return;
}
}
Good luck!

Uncaught TypeError: Cannot read properties of null (reading 'uid') : Get this error but application work fine?

I get this error upon logging out: (Uncaught TypeError: Cannot read properties of null (reading 'uid')), but my application works and does what I want it to do.
Within my logout function I am basically deleting an API access token from the user doc in the database when user logouts, because the token does not expire so it is added on login and removed on logout as part of authentication process. This all works fine.
so how do I get rid of this error, is there another way I can structure my code to get rid of this error?
It makes sense that this error appears once user has logged out because the uid is longer available to access due to user not being active (current user).
Many thanks, code below.
import { signOut } from "#firebase/auth";
import { useNavigate } from "react-router";
import { auth, db } from "../../firebase";
import { doc, updateDoc, deleteField } from "firebase/firestore";
export const Logout = () => {
const user = auth.currentUser;
const uid = user.uid;
console.log(uid);
const userRef = doc(db, 'users', uid);
const navigate = useNavigate();
const logoutUser = async () => {
//Deleting mavenlink access token
await updateDoc(userRef, {
accessToken: deleteField()
});
signOut(auth).then(() => {
navigate("/")
})
}
return {logoutUser}
};
For context below is code where authenticated routes are handled in app.js
function App() {
const [isAuthenticated, setIsAuthenticated] = useState(false);
const [state, setState] = useState({});
const [user, loading, error] = useAuthState(auth);
//Hook to handle authentication
useEffect(() => {
if (loading) {
// maybe trigger a loading screen
return;
}
if (user && !isAuthenticated){
setIsAuthenticated(true);
console.log("logged in");
} else if (!user && isAuthenticated) {
setIsAuthenticated(false);
console.log("logged out");
}
}, [user, loading]);
const unauthenticatedRoutes = useRoutes([
{ path: "/", element: <LoginForm/> },
{ path: "/reset", element: <ResetForm/> },
{ path: "/register", element: <RegisterForm/> },
]);
return (
<AppContext.Provider value={{
isAuthenticated, setIsAuthenticated,
}}>
<div className="App">
{!isAuthenticated ? <>{unauthenticatedRoutes}</> : <Sidebar/>}
</div>
</AppContext.Provider>
);
}
export default App;
Note: the authenticated routes are defined in the sidebar component and rendered there.

You may add privateRoutes to resolve this issue.
What I mean by this is create a file where you specify the condition whether your component should be rendered, or it should redirect to signin page.
And you can convert your normal route to private route. wrap your element in private route in your normal route. When you make your signout function a private component it will redirect the user to signin page as now user is deleted and currentUser no longer exist.
import React from 'react';
import { Navigate} from 'react-router-dom';
//import user from firebase
export default function PrivateRoute({ children }) {
const { currentUser } = // user imported
return currentUser ? children : <Navigate to="/signin" />;
}

expo auth response is always null

I've searched on here already but it seems all the answers are very outdated or they are questions that haven't been answered.
I've got an expo app SDK 43 and I'm using their auth library to authorize a reddit login. I've followed the example here https://docs.expo.dev/guides/authentication/#reddit to produce this code
import React from 'react';
import * as WebBrowser from 'expo-web-browser';
import { makeRedirectUri, ResponseType, useAuthRequest } from 'expo-auth-session';
import { Button } from 'react-native-paper';
import { useAppDispatch } from '../../common/hooks/redux';
import { setAuthCode } from '../../common/state/authSlice';
WebBrowser.maybeCompleteAuthSession();
// Endpoint
const discovery = {
authorizationEndpoint: 'https://www.reddit.com/api/v1/authorize.compact',
tokenEndpoint: 'https://www.reddit.com/api/v1/access_token',
};
const LoginScreen = () => {
const dispatch = useAppDispatch();
const [request, response, promptAsync] = useAuthRequest(
{
responseType: ResponseType.Token,
clientId: 'MY_CLIENT_ID',
scopes: ['identity'],
redirectUri: makeRedirectUri({
scheme: undefined,
}),
},
discovery
);
React.useEffect(() => {
console.log(`response is ${response}`);
if (response?.type === 'success') {
const { access_token } = response.params;
dispatch(setAuthCode(access_token));
console.log(access_token);
} else {
console.log(response);
}
}, [response]);
return (
<Button
disabled={!request}
onPress={() => {
promptAsync();
}}
>
Login
</Button>
);
};
export default LoginScreen;
But despite the fact that the login button correctly takes me to the login screen, I successfully log in and allow the app (and if I go onto the web separately I can see in my account that the app is there under the authorized apps.)
At this point on my device one of two things happens: 1. something causes the app to disconnect from metro and it hangs on a loading wheel belonging to the greater expo stuff, or 2. It successfully gets back to the app but it redownloads the bundle and the response is null.
What is screwing up here?

React - Firebase handling Auth persistence using a separate auth class

I am building a react app that uses a simple login feature. I am only using google sign in, and am calling the signInWithPopop function to handle that. I have created a separate class to handle all the auth related code. On the navbar of my website I have a login button if the user is not signed in which switches to a profile button when the user has signed in.
This is how I am currently checking if the user is signed in (not working):
console.log(authHandler.getUser());
const[loginState, setLogin] = useState(authHandler.getUser()? true : false);
return(
<div className="navbar">
<div className="nav-options">
<NavItem name="About"></NavItem>
<NavItem name="Listings"></NavItem>
<NavItem name="Dashboard"></NavItem>
{loginState ? <NavItem name="Profile"><DropDown loginState={setLogin}></DropDown></NavItem> : <NavItem name="Login" click={() => authHandler.signIn(setLogin)}></NavItem>}
</div>
</div>
);
This is what I have for my authHandler class:
import firebase from 'firebase';
export default class Auth{
constructor(){
var firebaseConfig = {
...
};
!firebase.apps.length? firebase.initializeApp(firebaseConfig) : firebase.app();
firebase.analytics();
this.provider = new firebase.auth.GoogleAuthProvider();
}
signIn(state){
firebase.auth().setPersistence(firebase.auth.Auth.Persistence.SESSION).then(() => {
return firebase.auth().signInWithPopup(this.provider).then((result) => {
console.log("signed in " + result.user.uid);
this.user = result.user
state(true);
}).catch((error) => {
console.log(error.message);
});
}).catch((error) => {
console.log(error.message);
})
}
getUser(){
return firebase.auth().currentUser;
}
logout(state){
//TODO: logout of firebase
state(false);
}
}
I have tried adding session and local persistence on firebase, but when I refresh the page, the user is signed out. What would be the proper way of maintaining persistence, in a separate class like this? I am trying to build this app with best practices in mind so that the code will be split up properly, and security is maintained.
Thanks!

You're supposed to use an auth state observer to get a callback whenever the user's sign in state changes. When a page first loads, the user is always immediately considered to be signed out. The callback will be invoked some time soon after the user's token has been loaded from persistence and verified. Use this state callback to determine what to render.
firebase.auth().onAuthStateChanged((user) => {
if (user) {
// User is signed in, see docs for a list of available properties
// https://firebase.google.com/docs/reference/js/firebase.User
var uid = user.uid;
// ...
} else {
// User is signed out
// ...
}
});
You might want to show a loading screen until the first callback tells you for sure if the user was previously signed in or is definitely signed out.
I suggest reading this for more information.

The way I implemented the auth state in react :
Auth.provider.tsx
import React, {
FC,
createContext,
useContext,
useEffect,
useState,
} from 'react';
import { User, auth } from 'firebase/app';
interface AuthContext {
user: User | null;
loading: boolean;
}
const defaultAuthContext = { user: null, loading: false };
const AuthUserContext = createContext<AuthContext>({ ...defaultAuthContext });
export const AuthUserProvider: FC = ({ children }) => {
const [authContext, setAuthContext] = useState<AuthContext>({
user: null,
loading: true,
});
useEffect(
() =>
auth().onAuthStateChanged((authUser) =>
setAuthContext({ user: authUser, loading: false }),
),
[],
);
return (
<AuthUserContext.Provider value={authContext}>
{children}
</AuthUserContext.Provider>
);
};
export const useAuthUser = () => useContext(AuthUserContext);
App.tsx
const App: React.FC = () => {
return <AuthUserProvider>
// anything
</AuthUserProvider>;
}
anycomponent.tsx
const { user, loading } = useAuthUser();
return loading ? <Loader /> : !user ? <NotLogged /> : <Logged />;
You could implement the observer in your class but everytime you'll need your user you should implement an useEffect watching the user. Making it global in a provider make it easier to use.
There are many other way but I think this one is the easiest to use.

Connection to Facebook with React and Firebase

i'm french, sorry for my little english.
I've a problem with Reactjs and Firebase, an error when i want connect with Facebook. I look tutorial in Udemy platform. This is a video for learn React
REBASE: The Firebase endpoint you are trying to listen to must be a string. Instead, got undefined
Parts of code Admin.js :
import React, { Component } from 'react'
import AjouterRecette from './AjouterRecette'
import AdminForm from './AdminForm'
import Login from './Login'
import firebase from 'firebase/app'
import 'firebase/auth'
import base, { firebaseApp } from '../base'
class Admin extends Component {
state = {
uid: null,
chef: null
}
componentDidMount () {
firebase.auth().onAuthStateChanged(user => {
if (user) {
this.handleAuth({ user })
}
})
}
handleAuth = async authData => {
console.log(authData)
const box = await base.fetch(this.props.pseudo, { context: this })
if (!box.chef) {
await base.post(`${this.props.pseudo}/chef`, {
data: authData.user.uid
})
}
this.setState({
uid: authData.user.uid,
chef: box.chef || authData.user.uid
})
}
authenticate = () => {
const authProvider = new firebase.auth.FacebookAuthProvider()
firebaseApp
.auth()
.signInWithPopup(authProvider)
.then(this.handleAuth)
}
...
export default Admin
Thank's
Have a good day.
......................................................................................................................................................................................................................................................................................................................................................................................................

I've got exactly the same problem, probably because I follow the same training as you.
Your error is here :
const box = await base.fetch(this.props.pseudo, { context: this })
because this.props.pseudo is null.
in app.js, in the admin component, write
pseudo={this.props.match.params.pseudo}
and not
pseudo={this.state.pseudo}
and that shoudl work.
regards