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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/9954ffee-6dca-42e0-9943-d73ad0137ed1%40googlegroups.com.
