Model renaming doesn't work backwards

[Andrew Godwin]

Because of the way ModelRename also triggers AlterField on the foreign keys of other models, it doesn't work in reverse, as that way round the foreign keys are repointed to the old model before it is re-created.

Since some backends (e.g. PostgreSQL) repoint constraints along with renames, we need to make sure that no AlterField is triggered with a rename and then have RenameModel deal with the FKs on MySQL (and perhaps Oracle?)

[Andrew Godwin]

I'm marking model renames as irreversible for now in order to move this away from release blocker status; there's other irreversible core operations, and we can address this if we get time before the final.

[Tim Graham]

There's a test in tests/migrations/test_operations.py (test_rename_model_with_related) that should be uncommented when this is fixed.

[Andrew Godwin <andrew@…>]

In 4ce7a6bc84c68406e39f48550434faeef3277eba:

Fixed #22750, #22248: Model renaming now also alters field FKs

[Andrew Godwin <andrew@…>]

In b568bdf8da30fe5940a31add9f3a2b8029ecb04d:

[1.7.x] Fixed #22750, #22248: Model renaming now also alters field FKs

[Stratos Moros]

Although this seems to be fixed by b568bdf, RenameModel.reversible is still False making RenameModel unreversible.

[Stratos Moros]

I've made a pull request for this: ​https://github.com/django/django/pull/3572.

[Simon Charette]

The Triage State refers to the ticket and not the patch.

Having Has patch checked with Patch needs improvement unchecked will ensure your patch shows up in the review queue.

[Stratos Moros]

Sorry about that, this is my first code contribution to Django. I'll keep it in mind for the future.

[Stratos Moros <stratos@…>]

In cf7a2a000e16b86dd721a021f1a2001529d8d707:

Fixed #22248 -- Made RenameModel reversible

[Tim Graham <timograham@…>]

In 50434aebe2d3307263ca55f6dd9fa7ace2f87d8f:

[1.7.x] Fixed #22248 -- Made RenameModel reversible

Backport of cf7a2a000e from master