Thanks, but the recursive foreignkey *is* a one to many relationship... unless you're talking about something else? *“None of you has faith until he loves for his brother or his neighbor what he loves for himself.”*
On Wed, Jul 27, 2022 at 10:16 AM Ammar Mohammed <[email protected]> wrote: > Hi > Have you tried using OneToMany relationship ? > On 27 Jul 2022 12:18, "Malik Rumi" <[email protected]> wrote: > >> I have a model with a recursive foreign key to 'self'. This is intended >> to model a parent child >> relation among instances. The forward relation, on a field called >> 'childof', works as expected. >> The reverse relation, using the related_name 'parent', comes up as a >> RelatedManager, >> again as expected. However, parent.count(), parent.all(), etc., always >> give me the "Manager is >> not accessible on instances" error. Many of these parent instances will >> themselves also be a >> childof some other instance, and apparently, that's my problem. I don't >> know how to make Django >> recognize the dual nature of some instances. Is there a way to hack the >> RelatedManager to fix this? >> >> I am not getting any accessor errors from manage.py check. >> >> I posted this to Django Forum, but the respondent was not able to >> duplicate my issue - i.e., >> he said it worked as expected for him. :-( >> >> I saw a suggestion to use an explicit junction table on Stack Overflow, >> but making a round trip - or two - to an external table seems like an >> awful lot of overhead for this situation. >> >> If instead of a junction table, if I made an explicit parentto field on >> the model, would that work? >> Presumably the related name on the childof field would still fail like it >> does now, >> but I would instead have the explicit parent field to work with. I still >> would not have the >> automatic reverse relation, and I would have to come up with a script to >> fill in the parentto >> field, but that might solve my problem: >> # pseudocode >> family = c.itertools.groupby(instance.childof) >> family = c.pandas.groupby(instance.childof) >> for f in family: >> pop = c.objects.get(instance.childof) >> OR >> pop = instance.childof >> c.objects.update(pop.parentto=f) # where parentto is a Postgresql >> ArrayField >> OR # >> https://docs.djangoproject.com/en/4.0/ref/models/relations/#django.db.models >> .fields.related.RelatedManager.add: >> >>> b = Blog.objects.get(id=1) >> >>> e = Entry.objects.get(id=234) >> >>> b.entry_set.add(e) # Associates Entry e with Blog b >> SEE ALSO: >> https://docs.djangoproject.com/en/4.0/topics/db/examples/many_to_one/ >> >> If I did this two field hack, then I don't really need either one to be >> ForeignKeys any more, >> do I? They could be a CharField and an ArrayField, couldn't they? That >> breaks the extended >> lookup chain - but I don't have that now, anyway - or at least, I only >> have it in one direction. >> >> -- >> 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/3555d391-9c9e-440f-a603-103c9ccdc858n%40googlegroups.com >> <https://groups.google.com/d/msgid/django-users/3555d391-9c9e-440f-a603-103c9ccdc858n%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to a topic in the > Google Groups "Django users" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/django-users/xGtwxhx2Nrw/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-users/CAHs1H7tjom_GRucP8Dx3x8AzQobS4GCva8a0nuN3bEWVB2Taqw%40mail.gmail.com > <https://groups.google.com/d/msgid/django-users/CAHs1H7tjom_GRucP8Dx3x8AzQobS4GCva8a0nuN3bEWVB2Taqw%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- 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/CAKd6oBxYfR6ntzGe8EGbnm0z6%2BxjiJDP5nmg9kF5kuB9pCZiEg%40mail.gmail.com.
