SA Middleware

sa_middleware.py

class SqlAlchemyMiddleware:
    """
    A simple SA middleware class that creates a global scoped session from the
    DATABASE_URL parameter in the settings file.

    """
    def process_view(self, request, view_func, view_args, view_kwargs):
        from django.conf import settings
        from django.http import HttpResponseRedirect
        try:
            self.bind_session(request, view_kwargs)
        except Exception, e:
            if settings.DEBUG:
                raise
            else:
                return HttpResponseRedirect(settings.LOGIN_URL)

    def process_response(self, request, response):
        Session.remove()
        clear_engine_cache()
        return response

    def bind_session(self, request, view_kwargs):
        from django.conf import settings
        Session.configure(bind = create_cached_engine(settings.DATABASE_URL))

where did the create_cached_engine method come from?