I've found myself in the situation of needing to copy model data to new model instances. This rapidly turned into a twisty sort of hell where I was doing recursion on graphs in order to preserve all the foreign key references (and then special-casing all the OneToOne fields, because naively copying those will throw IntegrityErrors right and left...) Now it is one of those unmaintainable-horror corners of the codebase that no one wants to go near.
Just back up your whole database. If you're using postgres, pg_dump makes this really straightforward. On Sun, Oct 16, 2016 at 2:40 AM, Bernd Wechner <bernd.wech...@gmail.com> wrote: > A curious question I've had trouble finding an answer for alas. I have a > model that I'd like to backup in the database in a backup model. This being > the pro-forma so to speqk: > > from django.db import models > > class MyModel(models.Model): > # Declare fields .... > > class MyModel_backup(MyModel): > def create(self): > self.objects = MyModel.objects.all() > > But there are two immediate problems. > > 1. Deriving from MyModel reveals itself in the migration to be > generating a model which has a single OneToOne reference to MyModel. That > is ti does not appear to create a duplicate model at all. Which leaves me > wondering how to create a duplicate model without repeating the code. > > 2. I have no really idea how to copy all the objects of MyModel to a > new model. > > I may be approaching it poorly and am open to better ideas. I'm used to > doing it in SQL, essentially having an identically defined backup table, > just copying data to that table before doing a (risky) table wide operation > on the first. > > I could of course export a serialized backup to a disk file, but am > exploring options for keeping one backup in the database itself. > > I'd rather, I admit hear options for doing that than philosophic > appraisals of the benefits of an in-database copy vs, database exports. > > Regards, > > Bernd. > > -- > 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 django-users+unsubscr...@googlegroups.com. > To post to this group, send email to django-users@googlegroups.com. > Visit this group at https://groups.google.com/group/django-users. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/django-users/a19ba010-572b-4097-a988-f357cc5b6c31%40googlegroups.com > <https://groups.google.com/d/msgid/django-users/a19ba010-572b-4097-a988-f357cc5b6c31%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- Andromeda Yelton Vice President/President-Elect, Library & Information Technology Association: http://www.lita.org http://andromedayelton.com @ThatAndromeda <http://twitter.com/ThatAndromeda> -- 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 django-users+unsubscr...@googlegroups.com. To post to this group, send email to django-users@googlegroups.com. Visit this group at https://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/CAFE1XCYW9cLixRSG2bmBM3Knm0hhf_4q%2BcZvuvvXcDPZmf9nKw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
