state example

middleware.py

class History(LimitedOrderedSet):
    def get_products(self):
        return get_products_list(products=",".join(map(str, self)))


class ShopState(object):
    """
    :type history: History
    """

    def __init__(self):
        self.history = None

        self.init()

    def init(self):
        if not self.history:
            setattr(self, 'history', History(limit=5))

    def __repr__(self):
        return pformat(self.__dict__)


class ShopMiddleware(object):
    session_key = '__state'

    def process_request(self, request):
        request.state = request.session.get(self.session_key, ShopState())

    def process_response(self, request, response):
        request.session[self.session_key] = request.state

        return response

usecase.py

        self.request.state.history.add(product.id)

        context.update({
            'product': product,
            'viewed': self.request.state.history.get_products()
        })