[FIXED] How can I tell django how to revert custom migration?

Issue

I have two simple migrations:

0001_initial.py

# Generated by Django 4.2.7 on 2023-11-30 11:15

from django.db import migrations, models


class Migration(migrations.Migration):
    initial = True

    dependencies = []

    operations = [
        migrations.RunSQL(
            """
            CREATE TABLE comments (
                id SERIAL PRIMARY KEY,
                contents VARCHAR(240) NOT NULL 
            );
            """
        ),
    ]

0002.py

# Generated by Django 4.2.7 on 2023-11-30 11:15

from django.db import migrations, models


class Migration(migrations.Migration):

    dependencies = [
        ("polls", "0001_initial")
    ]

    operations = [
        migrations.RunSQL(
            """
            ALTER TABLE comments RENAME COLUMN contents to text;
            """
        ),
    ]

I run:

python manage.py migrate

Then I want to undo the 0002 migration

I run

python manage.py migrate polls 0001

But Django does not know how to undo the changes from the second migration.

How can I tell Django that for undoing the changes from the 0002 migration I need to run this SQL:

ALTER TABLE comments RENAME COLUMN text to contents;

I tried searching but without success.

Solution

The RunSQL migration ^[Django-doc] takes a second optional parameter where you can specify the reverse migration, so:

class Migration(migrations.Migration):

    dependencies = [('polls', '0001_initial')]

    operations = [
        migrations.RunSQL(
            'ALTER TABLE comments RENAME COLUMN contents TO text;',
            'ALTER TABLE comments RENAME COLUMN text TO contents;',
        ),
    ]

If you then migrate to:

manage.py migrate polls 0001

it will look if all migrations have a reverse operation, and take that query.

Answered By - willeM_ Van Onsem