#18889: Provide a simple way to retain parent instances after children are
deleted
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Reporter: anonymous | Owner: nobody
Type: New feature | Status: new
Component: Database layer (models, ORM) | Version: 1.4
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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I have a Location table with two children (using table-inheritance):
Restaurant and ChipShop. There should be a simple way to convert a
ChipShop to a Restaurant without deleting/recreating the Location which
may be referenced by lots of foreign keys, e.g:
{{{
location = Location.objects.get(1) # Currently a ChipShop
restaurant = Restaurant(location_ptr=location)
restaurant.save()
location.chipshop.delete() # Deletes the ChipShop row but not the Location
}}}
Currently this can be achieved by using raw sql to bypass django's code
that deletes the parent when a child is deleted. Doing the following does
not work as the parent is still deleted, perhaps this is a bug?
{{{
class ChipShop(Location);
location_ptr = models.OneToOneField(Location, on_delete=DO_NOTHING,
parent_link=True)
}}}
Modifying the on_delete of the created location_ptr does nothing as well.
Perhaps a setting in the parents Meta that could be used to specify that
the parent should not be deleted when the child is?
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Ticket URL: <https://code.djangoproject.com/ticket/18889>
Django <https://code.djangoproject.com/>
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