base.py

from flask import session, redirect
from flask import request
from models import User
from functools import wraps

def set_user(user):
	session["user"] = user.id

def get_user():
	if "user" in session:
		return User.query.filter(User.id == session["user"]).scalar()
	else:
		return None

def user_optional(handler):

	@wraps(handler)
	def check_login(*args, **kwargs):
		return handler(*args, **kwargs)

	return check_login

def user_required(handler):

	@wraps(handler)
	def check_login(*args, **kwargs):
		user = get_user()
		if not user:
			session["last_page_before_login"] = request.path + "?" + request.query_string
			return redirect("/")
		else:
			return handler(*args, **kwargs)

    	return check_login