#27092: MIgrations: Creating and then renaming a ForeignKey fails when index and
constraint created
-----------------------------+--------------------
Reporter: alexsdutton | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: 1.10
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
-----------------------------+--------------------
Minimal test case at https://github.com/ox-it/create-rename-foreignkey-
testcase; example Travis run at https://travis-ci.org/ox-it/create-rename-
foreignkey-testcase/jobs/153535976.
The following migration fails:
operations = [
migrations.CreateModel(
name='Planet',
fields=[
('id', models.AutoField(verbose_name='ID',
serialize=False, auto_created=True, primary_key=True)),
],
),
migrations.CreateModel(
name='Star',
fields=[
('id', models.AutoField(verbose_name='ID',
serialize=False, auto_created=True, primary_key=True)),
],
),
migrations.AddField(
model_name='planet',
name='parent_star',
field=models.ForeignKey(to='crft.Star'),
),
migrations.RenameField(
model_name='planet',
old_name='parent_star',
new_name='star',
),
]
as it tries to create the foreign key constraint and index at the end
against the `parent_star_id` field, which has already been renamed to
`star_id`.
This arose for as when I wanted to replace a ForeignKey with another to a
different model, but perform a data migration from the old to the new. The
idea was: create new foreign key with temporary name, migrate data, remove
old foreign key, rename the new one to the original name.
I can get round it by first renaming the old field to a temporary name and
creating the new one with the name we want by the end, but this causes the
backwards migration to fail for the same reason.
--
Ticket URL: <https://code.djangoproject.com/ticket/27092>
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