#24951: Error deleting from table with Foreign Key being Primary Key at the same
point
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Reporter: grumbler | Owner: nobody
Type: Bug | Status: new
Component: Database layer (models, ORM) | Version: 1.8
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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Problem occurs, when trying to issue delete on queryset for a table like
this:
{{{
class Derivative(models.Model):
spot = models.OneToOneField(Spot, primary_key=True)
flag = models.BooleanField(default=True)
Derivative.objects.filter(spot__name__icontains='name').delete()
}}}
Result is:
AssertionError: Can only delete from one table at a time.
However, if we have simple table like this:
{{{
class SimpleDerivative(models.Model):
spot = models.OneToOneField(Spot)
flag = models.BooleanField(default=True)
}}}
than there is no problem. Note, there is no primary_key for spot here.
Problem does not exist for Django 1.6 (I didn't check for previous
versions)
And persits in 1.7 and 1.8
There is changed code between versions in:
django/db/models/sql/subqueries.py - DeleteQuery.delete_qs
right before the last line self.tables contains two tables, which leads to
assertion error.
I provided sample project to reproduce issue -
https://github.com/grumbler/django_delete_issue
Simply run the tests with the appropriate Django version installed.
--
Ticket URL: <https://code.djangoproject.com/ticket/24951>
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