(You can reopen https://code.djangoproject.com/ticket/24141 rather than creating a new ticket.)
On Friday, June 5, 2020 at 9:06:48 AM UTC-4, Aymeric Augustin wrote: > > If people agree QuerySet.contains() should be added, how do we move > forward? > > > Yes, if there's no major new argument in a couple days, we can assume > consensus on adding .contains(). > > * Create a ticket in Trac. Point to this discussion and to the previous > ticket where .contains() was suggested. > * Submit a pull request in GitHub with code, tests, docs. This is worth > mentioning in the changelog. > > There's a lot of details in the docs, in the Contributing Guide, about how > to do allD this right. > > -- > Aymeric. > > > > On 5 Jun 2020, at 13:58, Johan Schiff <jo...@radkompaniet.se <javascript:>> > wrote: > > Shai does make a good point about changing a well documented behaviour. > That argument wins me over. > > Adding .contains() and updating the documentation goes a long way to make > it easier for developers. > > Best case would be that Dajngo does not make assumptions about what the > developer wants, but to implement __len__(), __bool__() and __contains__(), > we have to assume one method or the other. I still think the wrong call was > made here, but changing it now is too much pain. *(Assuming queryset > should be evaluated is probably correct in most cases, but sometimes adds a > big performance hit when the code goes into production and the dataset > grows - code that looks reasonable and works like a charm in dev will cause > trouble in production. Assuming the opposite would have added a tiny > performance hit in most cases, but avoided the big one.)* > > Since I'm new here: > If people agree QuerySet.contains() should be added, how do we move > forward? > I'd be willing to write some code with tests and add a ticket, if that's > helpful. > > Le ven. 5 juin 2020 à 11:42, אורי <u...@speedy.net <javascript:>> a > écrit : > >> Hi, >> >> I'm thinking, maybe instead of: >> >> if obj in queryset: >> >> Users should write: >> >> if obj in list(queryset): >> >> Which I understand is already working? Why does the first line (without >> list()) should work anyway? >> >> And if users want performance, why not write: >> >> if queryset.filter(pk=obj.pk).exists(): >> אורי >> u...@speedy.net <javascript:> >> >> >> On Tue, Jun 2, 2020 at 11:57 AM Johan Schiff <jo...@betahaus.net >> <javascript:>> wrote: >> >>> Is there a specific reason Djangos QuerySet does not implement >>> __contains__? It doesn't seem very complicated to me, but maybe I'm missing >>> something. >>> >>> When checking if an object is in e queryset I always use code lite this: >>> if queryset.filter(pk=obj.pk).exists(): >>> >>> The pythonic way would be: >>> if obj in queryset: >>> >>> The way I understand it this latter version will fetch all objects from >>> queryset, while the first one is a much leaner db query. >>> >>> So, is there a reason QuerySet doesn't have a __contains__ method, or >>> would it be a good addition? My guess is that a lot of people use the "obj >>> in queryset" syntax, believing it does "the right thing". >>> >>> //Johan >>> >>> -- >>> 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 <javascript:> >>> . >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/django-developers/88c83b8d-658c-47cc-9162-fcfebebe9c4a%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/django-developers/88c83b8d-658c-47cc-9162-fcfebebe9c4a%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> >> -- >> You received this message because you are subscribed to a topic in the >> Google Groups "Django developers (Contributions to Django itself)" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/django-developers/NZaMq9BALrs/unsubscribe >> . >> To unsubscribe from this group and all its topics, send an email to >> django-developers+unsubscr...@googlegroups.com <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/django-developers/CABD5YeE7_ORUfJcnt6f4aB4J0j-%3DyDK_BowEt_fefcaFMGdB1g%40mail.gmail.com >> >> <https://groups.google.com/d/msgid/django-developers/CABD5YeE7_ORUfJcnt6f4aB4J0j-%3DyDK_BowEt_fefcaFMGdB1g%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > > > -- > Vänligen, Johan Schiff > Radkompaniet AB > 072-229 61 19 > > -- > 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 <javascript:>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-developers/CAD69rUBKOse%2Be2RedPT%2B-KWkcdC%3DiaG0zyt1Hakefp6gQ7vdLA%40mail.gmail.com > > <https://groups.google.com/d/msgid/django-developers/CAD69rUBKOse%2Be2RedPT%2B-KWkcdC%3DiaG0zyt1Hakefp6gQ7vdLA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > > -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. 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