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>
> 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.
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