Django - wont let me add a new field to my model because 1054, "Unknown column 'field list'")

Question

I am trying to simply add a boolean field to a model in my database following the simple rules:

- add field to model
- python manage.py makemigrations app
- python manage.py migrate app

Works all but 99% of the time. So during the second step (makemigrations), with my newly added field in my model raring to go, i get an error:

django.db.utils.OperationalError: (1054, "Unknown column 'model.field' in 'field list'")

Excellent. its not letting me make migrations by adding a new field..... because it cant find the field that I am trying to newly add... makes perfect sense!

Anyway, I have gone as far as deleting all my migrations, removing my new field, making migrations again, migrating... all fine - so now i have only 1 migration file (0001)...

Follow the same steps as above... ERROR

Am i missing something ridiculous here? I mean, adding a field to a model is very simple, and I have done it probably 1000 times. Why does Django tease me so

EDIT: Answer:

OK I have done it.

After deleting the migrations file, truncating the migrations table and migrating with 0001_initial.py, I made an empty migrations file (python manage.py makemigrations --empty app) and added the field in manually.... then I migrated and it worked! Baffled at this to be honest, but at least the change has been made:

• Delete all migration files
• Truncate the django_migrations table
• comment the new boolean field
• run python manage.py makemigrations
• run python manage.py migrate --fake
• run python manage.py makemigrations --empty app

• add field in manually to the empty migrations file in the operations:

  migrations.AddField('modelName', 'fieldName', models.BooleanField(default=False)),
  

• run python manage.py migrate

• uncomment the new boolean field so it represents what you made in the migrations operations

Answer 1

This is an issue that has persisted with me and lead me down a lot of rabbit holes dropping tables etc. A simple solution I have found is answering "N" when django asks you if you are renaming a field of that model (when running makemigrations). What that then essentially performs is a deletion of your previous field and creates the new field. Be careful as you may lose data on existing field so this works with fields which are either new or relatively easy to 'refill' their data required. You may need to run --fake if you get an error with regards to not being able to 'drop field' when migrating after makemigrations. If you would like to go back to your migration state before the problem you may need to delete the migrations you have done since then and try the above solution.

Update: I did the above for a Boolean field and my data was kept. Even though I said N, it seems as if it is essentially a renaming.

Answer 2

Another source of the problem: I have a ModelForm based on the model. The ModelForm definition defines two extra fields. I had to comment out those two fields from the Form definition before doing the migration steps. Once the migration was done, I un-commented the two fields.