I think that should work but I haven't tried it.
What happens if you delete the first line "session.cart_items=..."? That's
going to keep overwriting cart_items each time the controller is called.
You might have to ensure that cart_items is a list:
items = session.cart_items
if request.vars:
if not session.cart_items:
session.cart_items = []
session.cart_items.append({'id':request.vars.id
,'qty':request.vars.qyt})
The other thing I'm wondering is if you might need to re-write the list
each time:
items = session.cart_items or []
if request.vars:
items.append({'id':request.vars.id ,'qty':request.vars.qyt})
session.cart_items = items
