makemigrations seems to generate an unnecessary AlterField

[Matthew Cornell]

I have a model that's evolved over time. I needed to hand-code my last migration ( migrations/0017_forecast_issued_at.py ) to migrate existing data from a DateField to a DateTimeField. However, when I then run makemigrations ( migrations/0018_auto_20210601_0946.py ), it generates what looks to me like a redundant AlterField operation where it wants to set the new DateTimeField's db_index=True even though it's already True in the previous (0017) migration. I've attached the model file ( models/forecast.py ) plus the two migration files. Questions: Is this behavior expected? Thank you!

[Christos Georgiou]

In 0017 you AlterField to:
field=models.DateTimeField(db_index=True, default=None, null=False),
which doesn't make much sense (null=False and yet default=None).
Have you tried to remove the AlterField's default=None to see if still 0018 is produced by makemigrations?

[Mariusz Felisiak]

Please don't use Trac as a support channel, this is a manually created migration. To avoid creation of 0018_auto_20210601_0946.py​ you can change the AlterField to the:

        migrations.AlterField(
            model_name='forecast',
            name='issued_at',
            field=models.DateTimeField(db_index=True),
        ),

default=None is not the same as not providing a default.

Closing per TicketClosingReasons/UseSupportChannels.

[Matthew Cornell]

Genius! Thanks very much.

Replying to Christos Georgiou:

In 0017 you AlterField to:
field=models.DateTimeField(db_index=True, default=None, null=False),
which doesn't make much sense (null=False and yet default=None).
Have you tried to remove the AlterField's default=None to see if still 0018 is produced by makemigrations?

[Matthew Cornell]

Thank you. Apologies.

Replying to Mariusz Felisiak:

Please don't use Trac as a support channel, this is a manually created migration. To avoid creation of 0018_auto_20210601_0946.py​ you can change the AlterField to the:

        migrations.AlterField(
            model_name='forecast',
            name='issued_at',
            field=models.DateTimeField(db_index=True),
        ),

default=None is not the same as not providing a default.

Closing per TicketClosingReasons/UseSupportChannels.