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How to modify a queryset and save it as new objects?

I need to query for a set of objects for a particular Model, change a single attribute/column ("account"), and then save the entire queryset's objects as new objects/rows. In other words, I want to duplicate the objects, with a single attribute ("account") changed on the duplicates. I'm basically creating a new account and then going through each model and copying a previous account's objects to the new account, so I'll be doing this repeatedly, with different models, probably using django shell. How should I approach this? Can it be done at the queryset level or do I need to loop through all the objects?


# Now I need to set account = "acct_2" for the entire queryset, 
# and save as new rows in the database
like image 874
B Robster Avatar asked Mar 25 '23 05:03

B Robster

1 Answers

From the docs:

If the object’s primary key attribute is not set, or if it’s set but a record doesn’t exist, Django executes an INSERT.

So if you set the id or pk to None it should work, but I've seen conflicting responses to this solution on SO: Duplicating model instances and their related objects in Django / Algorithm for recusrively duplicating an object

This solution should work (thanks @JoshSmeaton for the fix):

models = MyModel.objects.filter(account="acct_1")
for model in models:
  model.id = None
  model.account = "acct_2"

I think in my case, I have a OneToOneField on the model that I'm testing on, so it makes sense that my test wouldn't work with this basic solution. But, I believe it should work, so long as you take care of OneToOneField's.

like image 149
bozdoz Avatar answered Mar 30 '23 15:03