Btukfyl

I'm building an e-commerce website, I enable guest users to add products to their carts saving the cart_id in session and when they proceed to checkout, I redirect them to login as follows inside the checkout view

if not request.user.is_authenticated:

    login_url = reverse('accounts:login')

    check_out_url = reverse('cart:checkout')

    redirect_url = "{}?next={}".format(login_url, check_out_url)

    return redirect(redirect_url)

# checkout process here

It works, however the cart_id is no longer in the session.
If I don't use the next parameter and just redirect to login_url the cart_id stays in session.

P.S:
Same thing happens with login_required_decorator

Is there a way to keep the session data intact ?

We'd need more info to know for sure, but here's a best guess based on experience:

Are you sure the redirect is taking you to the same domain, in cookie terms?

eg, if you're authenticated on foo.somedomain.com and the next references www.somedomain.com, then Django (by default) will want to use separate cookies for those two, separate domains.

To make Django use a cookie across all subdomains for a given domain, you'll want to set settings.SESSION_COOKIE_DOMAIN (docs) to just the domain. eg somedomain.com