for some reason i want to use "request" in AUTHENTICATION_BACKENDS
but i got request as None

i need request because:

1. shopping cart is in cookie before login
2. shoping cart is in server after login
3. i want to decorate anywhere when login ( logon 、login 、oauth2)
4. in my decoration : i get user from request
5. i write a new AUTHENTICATION_BACKENDS give User to request as user property
   no request no user

just change you serializers line 50
from
user = authenticate(**credentials)
to
user = authenticate(self.context["request"] , **credentials)

thanks