#24424: Removing a model's last field results in SQL syntax error on SQLite
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Reporter: adnam | Owner:
Type: Bug | Status: new
Component: Migrations | Version: 1.7
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
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Comment (by MarkusH):
Replying to [comment:21 jwineinger]:
> When you say "it is not about a DeleteModel operation following a
RemoveField. That could just remove that field", what do you mean?
If you have `RemoveField('mymodel', 'myfield')` followed by a
`DeleteModel('MyModel')` operation, I can't construct a case where Django
would end up constructing those two operations automatically where the
`RemoveField` would create a model without fields. A single `DeleteModel`
operation should be sufficient to drop the table and all its constraints.
> Should the approach be to change the auto-detector to not produce states
with zero columns, or should we try and handle that somewhere else?
Giving this issue more thoughts, I think the only way to prevent the
autodetector to construct states with models without fields is making the
`AlterField` operation smarter. Furthermore, when `RemoveField` would drop
the last field on a model, an `AlterField` operation must be used that
then can take care of the steps I outlined in [comment:20 comment 20].
This is only necessary for primary keys, though, I think. All other cases
can be fixed by first adding the new field and then removing the old
field.
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Ticket URL: <https://code.djangoproject.com/ticket/24424#comment:22>
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