Hello there, >From looking at your code (super() calls) it seems like your are using Python 2.
We've seen similar reports about stdlib functions hiding system level exceptions instead of surfacing them[0] so that might it. It's hard to tell without the full traceback though. Best, Simon [0] https://code.djangoproject.com/ticket/26600 Le lundi 7 octobre 2019 22:16:16 UTC-4, Abhijeet Viswa a écrit : > > Hey guys, > > I need a help with a quirky bug while iterating over a QuerySet: > >> TypeError: argument of type 'QuerySet' is not iterable > > > The following is the block of code that produces the error: (the save > method overrides the default save method in a Model called *Transaction*) > > def save(self, *args, **kwargs): > obj = self > if not obj.ref_number: # the line of code throwing the error > transactions = Transaction.objects.values_list("ref_number", > flat=True) # cache the list > while True: > ref_number = random.randint(1000000001, 9999999999) > if ref_number not in transactions: > obj.ref_number = ref_number > super(Transaction, obj).save(*args, **kwargs) > return > else: > super(Transaction, obj).save(*args, **kwargs) > > > This piece of code was working fine until we had modified (what we thought > to be) an unrelated part of the source: (this is the modified line of code) > items = OrderItem.objects.prefetch_related('toppings').select_related( > 'item').select_related('item__category') > order = Order.objects.filter(uuid=order_uuid).prefetch_related( > Prefetch( > lookup='items', > queryset=items > ) > ).select_related('outlet').select_related('user').select_related( > 'outlet__group') \ > .select_for_update(of=('self', 'outlet')) > > > We basically added a call to the *select_for_update. *This was required > by us since we are modifying both the *Order *as well as *Outlet *models. > (Also, the *Transaction* model is a super-model for the *Order *model) > > My best guess is that the select_for_update locks certain rows of the the > *Order*, *Transaction *and a bunch of other models. This results in the > line of code failing because the query to list the value fails. However, I > tested this hypothesis out by running a *select_for_update*, populating > the *QuerySet *returned and then sleeping for a while while I ran a > different query on the Model for which rows were locked. This ran perfectly > fine, with no problems. > > We are using PostgreSQL as our backend database. Any help would be greatly > appreciated. > > Thanks > > -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/9954ffee-6dca-42e0-9943-d73ad0137ed1%40googlegroups.com.
