I am trying to send my variable 'backEndResponse' with its value from my Express.js backend to my React.js Frontend. I am not quite sure how to send a variable from the backend to the frontend. I have searched around and can't find any good resources. I would appreciate any help.
Express.js Backend
function getcookie(req) {
var authCookie = req.headers.cookie;
if (authCookie = req.headers.cookie) {
try {
return authCookie
.split('; ')
.find(row => row.startsWith('Auth='))
.split('=')[1];
} finally {
if (authCookie = result) {
backEndResponse = true
console.log(backEndResponse);
console.log(result);
} else {
backEndResponse = false
console.log(backEndResponse);
console.log(result);
}
}
} else {
}
}
app.get('/auth', (req, res) => {
getcookie(req)
if (backEndResponse) {
res.json(backEndResponse); // OR json({ message: "Authorised" })
} else {
res.json(backEndResponse); // OR json({ message: "Unauthorised" })
}
});
Frontend React.js
const useAuth = () => {
const [data, setData] = useState();
useEffect(() => {
const fetchAuthData = () => {
const result = axios('http://localhost:5000/auth');
console.log(result)
setData(result.data);
};
fetchAuthData()
}, []);
// Logic to check if backEndResponse is true or false
if (data) {
const authorized = {loggedIn: true}
return authorized && authorized.loggedIn;
} else {
const authorized = {loggedIn: false}
return authorized && authorized.loggedIn;
}
}
const ProtectedRoutes = () => {
const isAuth = useAuth();
return isAuth ? <Outlet/> : <Navigate to="/login" />;
}
You won't be able to send a variable directly, rather you will send a payload in a certain shape that best represents the data suited to the applications needs. To send a response payload in an express route use something like the following:
app.get('/auth', (req, res) => {
// do some logic for `backEndResponse`...
res.json(backEndResponse);
});
If you were intending to provide more information in the response such as HTTP headers differing based on the of backEndResponse then you might consider:
app.get('/auth', (req, res) => {
// do some logic for `backEndResponse`...
// send HTTP Ok if true, otherwise Bad Request
// consider handling 400 and/or 500 errors too
if (backEndResponse) {
res.status(200).json(true); // OR json({ message: "Authorised" })
} else {
res.status(401).json(false); // OR json({ message: "Unauthorised" })
}
});
A component fetching the above endpoint would be similar to:
const MyComponent = () => {
const [data, setData] = useState();
useEffect(() => {
const fetchAuthData = async () => {
const result = await axios('http://localhost:5000/auth');
setData(result.data); // true/false OR { message: "Authorised" }
};
fetchAuthData();
}, []);
// display payload
return (<div>{JSON.stringify(data)}</div>)
}
There is an opportunity to refactor the above into a custom hook should you find the need to reuse the functionality across multiple components.
axios request is async function, so you should do like that,
const useAuth = async () => {
try {
const res = await axios.get('http://localhost:5000/auth', {
withCredentials: true
})
return true
} catch (e) {
return false
}
};