Dear Sjoerd, dear all, My thoughts: * on one hand it feels natural to simplify calls and keep things simple, from this perspective +1; * on the other I can imagine new Django user that gets confused by inconsistency in code snippets or StackOverflow: you can now filter not only using filter() or get() methods, from this perspective -1; * get() already supports field lookups, so count() and exists() would join it to stand in one row, from this perspective +1; * if introducing such change, for sure documentation should be very carefully reviewed and updated to mirror the new preferred way of doing count and exists queries; * it would be quite a big change, I think it should be introduced with preferably MAJOR or at least MINOR version of Django; * maybe an e-mail encouraging community to update e.g. StackOverflow with new Django syntaxt sections after the release to avoid confusion for newcomers would be a good idea?; * what about first() and delete()? (rest of queryset methods with no arguments, that doesn't return a queryset); should they also support field lookups? * what about reverse() and all()? (rest of queryset methods with no arguments that return a queryset); should they also support field lookups?
Kind regards, Maciej Olko pt., 18 sty 2019 o 22:12 użytkownik Sjoerd Job Postmus <sjoerd...@sjec.nl> napisał: > Dear all, > > > This is probably a feature that has been proposed before, but I could > not find a discussion on it, so I proposed it on the tracker, and Tim > also couldn't find a discussion. > > (ticket: https://code.djangoproject.com/ticket/30118 ) > > I would like to propose being able to write > `SomeModel.objects.exists(field=value)` over > `SomeModel.objects.filter(field=value).exists()` (and similar for > `.count(**kwargs)`. > > > As Tim rightfully commented: "There should be one-- and preferably only > one --obvious way to do it.". > > > I'm proposing this is a case where the obvious way would eventually be > more in line with my suggestion instead of what we currently use. > > > Consider the following code example (from > > https://github.com/django/django/blob/709a8b861de14204f0e13c9a0fbfd61c11b3565d/tests/auth_tests/test_management.py#L998 > ): > > > Permission.objects.filter( > content_type__model=opts.model_name, > content_type__app_label=opts.app_label, > codename=codename, > ).exists() > > There is a weird (to me, your mileage might vary) ").exists()" as a > final line, and I would like to write this as > > Permission.objects.exists( > content_type__model=opts.model_name, > content_type__app_label=opts.app_label, > codename=codename, > ) > > This pattern seems to be quite rare in the Django codebase itself, but > in the codebase at work we have several cases of `queryset.filter(<lots > of lines>).exists()` (and similar with count), and I am expecting this > to also be prevalent in other codebases out there. > > > Arguing against it however are the following lines of the Zen of Python: > > - "Explicit is better than implicit." > > - Maybe also "Special cases aren't special enough to break the rules.", > because `.filter().count()` and `.exclude().count()` are both the same > pattern, but this would only create an alternative for the first. > > - "There should be one-- and preferably only one --obvious way to do it." > > > Beyond these short quips, I was hoping there might also be an earlier > discussion covering this. > > > Kind regards, > > Sjoerd Job Postmus > > -- > 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 post to this group, send email to email@example.com. > Visit this group at https://groups.google.com/group/django-developers. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-developers/63f21e13-4c6e-89f2-aca3-6961e98832df%40sjec.nl > . > For more options, visit https://groups.google.com/d/optout. > -- 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 post to this group, send email to firstname.lastname@example.org. Visit this group at https://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/CALYYG83gUsf7uc-w8_hUVKYxd_i%3DPshguRB4VLrA-c4g2k9R6g%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.