React - Rails. Rails session[:user_id] not persisting - ruby-on-rails

Question

I am building a React - Rails API application. Following a tutorial, I intentionally did not instantiate Rails as an API, rather it's the full framework. So, according to the the tutorial giver, I should have access to session and not have to download any gems.
Problem: When I refresh the page the session should keep the user logged in. It is not. Instead of returning with: { logged_in: true, user: {...} }, it is returning with { logged_in: false } (the else conditional in session's logged_in method). The #current_user from the concern file is returning as nil, more specifically, its session[:user_id] is returning nil, so the conditional is failing.
I'm out of ideas, I've been messing with this for over an hour and still no luck. If anything else is needed please let me know.
Rails: Sessions Controller
class SessionsController < ApplicationController
include CurrentUserConcern
def create
user = User.find_by(email: params["user"]["email"])
.try(:authenticate, params["user"]["password"])
if user
session[:user_id] = user.id
// binding.pry shows session[:user_id] = 4 (or whatever the id is)
render json: {
status: :created,
logged_in: true,
user: user
}
else
render json: { status: 401 }
end
end
// Method in question:
def logged_in
// #current_user == nil
if #current_user
render json: {
logged_in: true,
user: #current_user
}
else
render json: {
logged_in: false
}
end
end
def logout
reset_session
render json: { status: 200, logged_out: true }
end
end
Rails: controllers/concerns/current_user_concern.rb
module CurrentUserConcern
extend ActiveSupport::Concern
included do
before_action :set_current_user
end
def set_current_user
if session[:user_id]
// binding.pry shows session[:user_id] = nil
#current_user = User.find_by(id: session[:user_id])
end
end
end
React: App.js
// Method that is interacting with Rails
checkLoginStatus = () => {
axios
.get('http://localhost:3001/logged_in', { withCredentials: true })
.then((response) => {
// Does not enter the conditions RESPONSE = data.logged_in: false
if (response.data.logged_in && this.state.loggedInStatus === 'NOT_LOGGED_IN') {
this.setState({ loggedInStatus: 'LOGGED_IN', user: response.data.user });
} else if (!response.data.logged_in && this.state.loggedInStatus === 'LOGGED_IN') {
this.setState({ loggedInStatus: 'NOT_LOGGED_IN', user: {} });
}
})
.catch((error) => console.log('hello error.', error));
};

Answer 1

you need to add the following config.middleware.use ActionDispatch::Cookies
config.middleware.use ActionDispatch::Session::CookieStore to config/application.rb