React Remix not sending cookies to remote server - reactjs

Question

I am trying to set up authentication with Remix as my pure frontend and a django backend.
When the user signs in successfully, the backend sends a cookie with the response and this is set in the browser redirect with remix
const signIn = async (credentials: LoginCreds) => {
try {
const response = await fetch(generateFullBackendUrl('/auth/signin'), {
method: 'POST',
body: JSON.stringify(credentials),
headers: {
'Content-Type': 'application/json',
'Accept': 'application/json'
},
credentials: 'include'
});
return response;
} catch (e) {
console.log(e);
}
}
const response = await authService.signIn({
email,
password
})
const cookies = response?.headers.get('set-cookie');
if(cookies){
return redirect('profile', {
headers: {
'Set-Cookie': cookies
}
});
However when I try to make subsequent fetch calls in my loader the cookies are not sent to the backend as I would expect the browser would
await fetch(generateFullBackendUrl('api/users/me'), {
method: 'GET',
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json',
},
credentials: 'include'
})
Front end is running on port 3000
Backend running on port 4000
Im wondering why the fetch request in the loader does not send the cookies with the request

Answer 1

You need to read the cookie header from the loader request and pass it to your fetch headers.
There’s no way Fetch can automatically know what headers to send when used server side.

Answer 2

There is a quick workaround but not so elegant solution:
in your loader use this:
export const loader: LoaderFunction = async({request}) => {
const response = await fetch(`/api/books?${new URLSearchParams({
limit: '10',
page: '1',
})}`, {
headers: {
'Cookie': request.headers.get('Cookie') || ''
}
});
console.log(response)
if(response.ok) return await response.json();
}