Re: [Django] #33899: migrations.RemoveField causes OperationalError "no such column" upon migration when db_index=True (was: migrations.RemoveField causes OperationalError "no such column" upon migration)

[Django]

#33899: migrations.RemoveField causes OperationalError "no such column" upon
migration when db_index=True
-------------------------------------+-------------------------------------
Reporter: cessor | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: Migration Sqlite | Triage Stage: Accepted
Docker |
Has patch: 1 | Needs documentation: 0
Needs tests: 1 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by cessor:

Old description:

> == Description
>
> I encountered the following error with django 4.1 in my Gitlab CI/CD
> Pipeline. When I bumped django versions from 4.0.7 to 4.1. my pipeline
> broke during the testing stage; specifically during db migrations. I have
> not changed any other source code.
>
> == Steps to reproduce
>
> Minimal example attached. Run `make green` to see that it works with
> 4.0.7, run `make red` to see that it does not work with 4.1. It will
> build and exercise a docker container which installs all dependencies in
> isolation and sets up an example django app and run migrations.
>
> Manual steps:
>
> 0. Install django 4.1
> 1. Create a new project
> 2. Create an app
> 3. Install app in project
> 4. Create a model
> 5. Add field on model
> 6. Make migrations
> 7. Remove field
> 8. Make migrations
>
> The migration should fail.

New description:

== Description

I encountered the following error with django 4.1 in my Gitlab CI/CD
Pipeline. When I bumped django versions from 4.0.7 to 4.1. my pipeline
broke during the testing stage; specifically during db migrations. I have
not changed any other source code.

== Steps to reproduce

Minimal example attached. Run `make green` to see that it works with
4.0.7, run `make red` to see that it does not work with 4.1. It will build
and exercise a docker container which installs all dependencies in
isolation and sets up an example django app and run migrations.

Manual steps:

0. Install django 4.1
1. Create a new project
2. Create an app
3. Install app in project
4. Create a model
5. Add field on model, set `db_index=True`
6. Make migrations: `$ python manage.py makemigrations`
7. Remove field from model
8. Make migrations: `$ python manage.py makemigrations`
9. Apply migrations: `$ python manage.py migrate`

The migration fails with the following error (for an app called `web`,
with a model called `Entity` with a field called `attribute` for example):

```
Running migrations:
Applying contenttypes.0001_initial... OK
...
Applying sessions.0001_initial... OK
Applying web.0001_initial... OK
Applying web.0002_remove_entity_attribute...Traceback (most recent call
last):
File "/usr/local/lib/python3.10/site-
packages/django/db/backends/utils.py", line 89, in _execute
return self.cursor.execute(sql, params)
File "/usr/local/lib/python3.10/site-
packages/django/db/backends/sqlite3/base.py", line 357, in execute
return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: error in index web_entity_attribute_d22c3fcb
after drop column: no such column: attribute
```

== Details

The above steps create a set of migrations where at the end a
`RemoveField` migration is produced. Applying this migration fails for
fields which had `db_index=True`. The example I attached uses a SlugField
where `db_index` defaults to `True`, setting this parameter to False will
apply the migration without this error.

I reproduced the error with the following field types: TextField,
IntegerField, SlugField, CharField, URLField

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Ticket URL: <https://code.djangoproject.com/ticket/33899#comment:5>
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