Django Migration Error: Column does not exist

Question

Python 3, Django 1.8.5, Postgres

I have a model Sites that has been working fine. I recently tried to add a field, airport_code, and migrate the data.

Answer 1

In my case, that was because I had a unique_together constraint that was set.

When I wanted to remove a field, the auto-generated migration tried to remove the field before removing the unique_together constraint.

What I had to do was manually move up the migrations.AlterUniqueTogether constraint in the migration file, so that django removes first the constraint before trying to remove the field.

I hope this can help someone.

Answer 2

Late to the party, but there is some info I want to share. It helped me a lot! :)

I am using django-solo to store app config in database, and I got the same issue as Alex when adding new field to configuration model. Stacktrace pointed me to the line where I'm getting config from database: conf = SiteConfiguration().get_solo().

There is a closed issue for django-solo project on Github. The idea is to make model loading lazy (exactly as MrKickkiller pointed before).

So for modern Django version (in my case 3.0) this code works perfectly:

from django.utils.functional import SimpleLazyObject
conf = SimpleLazyObject(SiteConfiguration.get_solo)

Answer 3

Stuck into this issue recently.

In my case, I added a reference to a non-existing field in the code, then I came to the model file and added the new field, then tried to run makemigrations command which thrown the above error.

So I went to the stack trace all the way up and found the newly added reference was the problem. commented that out, ran makemigrations and voila.