在Python中的变量前附加0

Question

I have a variable called fab, and a Django queryset. As follows,

fab = self.request.GET.get('fab')

and my queryset,

queryset_df = Table1.objects.filter(Q(fab=int(fab)) | Q(fab=int(0+fab))).values_list('masks').distinct()

As seen I want to append a zero in front of the fab in my Q, because sometimes the fab comes as a integer value and sometimes with a 0 infront. When I tried to add by + , it returned me an error like, unsupported operand type(s) for +: 'int' and 'unicode' . Any idea why? Thanks in advance.

Answer 1

You should cast the 0 to unicode or string before concatenating.

fab = "0" + fab

You can not concatenate a unicode variable with an integer, you can also not concatenate strings with integers or floats, so you need to convert one to the correct type.

Answer 2

It sounds like your logic is wrong somewhere,

You are either trying to force an integer into a CharField or you are trying to force a string into an IntegerField . If its the former you're always going to struggle with having to cast values to get the correct results and if its the latter the leading 0 is pointless.

You should try to use the correct field type, it will even help with your model's validation.