repr(some_queryset) will execute the query and display some results from the query. This is done because it's (somewhat) helpful for debugging.
https://github.com/django/django/blob/2a6f45e08e8cb8c7e5157915c378b453109424d2/django/db/models/query.py#L248 This has caused at least two people to scratch their heads about odd queries being generated, and it crashed my production database yesterday. See #20393 <https://code.djangoproject.com/ticket/20393> and #30863 <https://code.djangoproject.com/ticket/30863> Luke Plant has said: ... you have a conflict between the goal of being information rich and with > *always* being useful for debugging. In general, automatically seeing the > results is information rich and is useful in debugging, but sometimes it > causes further problems. > > I have thought about it, and with this conflict of goals, I think we are > going to have to err on the side of the current behaviour. It is possible > to work around by not calling repr on QuerySets in your middleware, and > there are too many people who will be upset (or have problems with their > own debugging facilities) by changing this. > One reason people love Django is because of its attention to things like debug-ability. I can certainly see the argument here. However, I want to press on the desirability of this feature. The argument that you can work around it by not calling repr is certainly true, but in practice, I don't think it's reasonable. Production error reporting tools (like Sentry and New Relic) will call repr when reporting on exceptions. I see this behavior as being analogous to a file object printing the first 21 characters of a file, which it doesn't do (for good reason, I would imagine): >>> f = open("foo.py") >>> repr(f) "<_io.TextIOWrapper name='foo.py' mode='r' encoding='UTF-8'>" >>> I think we ought to reconsider the behavior of repr on QuerySets. I'm of the opinion that we should scrap it completely. It could be replaced by something that generates the SQL that would be executed (although that may be tricky), or some kind of representation of the query filter. Any thoughts? -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/29051be5-2988-4295-a8d9-1c5ae9555ee1%40googlegroups.com.
