Django Programming error column does not exist even after running migrations

问题

I run python manage.py makemigrations and I get: No changes detected Then, python manage.py migrate and I get: No migrations to apply.

Then, I try to push the changes to production: git push heroku master Everything up-to-date

Then, in production, I repeat the command: heroku run python manage.py migrate No migrations to apply.

Just in case, I run makemigrations in production:

heroku run python manage.py makemigrations
No changes detected

WHY then I get a

ProgrammingError at ....

column .... does not exist

"No changes detected" means the database is coherent with the code. How can I debug this?¡?

回答1:

Django migrations are recorded in your database under the 'django_migrations' table. This is how Django knows which migrations have been applied and which still need to be applied.

Have a look at django_migrations table in your DB. It may be that something went wrong when your migration was applied. So, delete the row in the table which has the migration file name that is related to that column that 'does not exist'. Then, try to re-run a migration.

回答2:

I got the same problem (column not exist) but when I try to run migrate not with makemigrations (it is the same issue I believe)

• Cause: I removed the migration files and replaced them with single pretending intial migration file 0001 before running the migration for the last change

• Solution:

  1. Drop tables involved in that migration of that app (consider a backup workaround if any)
  2. Delete the rows responsible of the migration of that app from the table django_migrations in which migrations are recorded, This is how Django knows which migrations have been applied and which still need to be applied.

And here is how solve this problem:

• log in as postgres user (my user is called posgres):

  sudo -i -u postgres

• Open an sql terminal and connect to your database:

  psql -d database_name

• List your table and spot the tables related to that app:

  \dt

• Drop them (consider drop order with relations):

  DROP TABLE tablename ;

• List migration record, you will see migrations applied classified like so:

id | app | name | applied
--+------+--------+---------+

SELECT * FROM django_migrations;

• Delete rows of migrations of that app (you can delete by id or by app, with app don't forget 'quotes'):

  DELETE FROM django_migrations WHERE app='yourapp';

• log out and run your migrations merely (maybe run makemigrations in your case):

  python manage.py migrate --settings=your.settings.module_if_any

Note: it is possible that in your case will not have to drop all the tables of that app and not all the migrations, just the ones of the models causing the problem.

I wish this can help.

回答3:

I had a similar issue - the error message appeared when I clicked on the model on the django-admin site. I solved it by commenting out the field in models.py, then running migrations. Following this I uncommented the field and re ran the migrations. After that the error message disappeared.

回答4:

So, I always run into this sort of problem, so today I decided to try and work it out at the database level. Thing is, I changed a model field name which Django didn't bother reflecting in a migration file. I only found out later when I ran into problems. I later looked at the migration files and discovered there was no migration for that change. But I didn't notice because I made other changes as well, so once I saw a migration file I was happy. My advice. Create migration for each change one at a time. That way you get to see if it happened or not.

So here's my working through it in MySQL.

open mysql console.

show databases; # see all my dbs. I deleted a few
drop database <db-name>; # if needed
use <db-name>; # the database name for your django project
show tables; # see all tables in the database
DESCRIBE <table-name>; # shows columns in the database
SHOW COLUMNS FROM <db-name>; # same thing as above
ALTER TABLE <table-name> CHANGE <old-column-name> <new-column-name> <col-type>; # now I manually updated my column name

If you're using postgresql, just google the corresponding commands.

回答5:

My case might be a bit obscure, but if it helps someone, it is worth documenting here.

I was calling a function in one of my migrations, which imported a Model of said migration regularly, i.e.

from myApp.models import ModelX

The only way models should be imported in migrations would be using e.g. RunPython:

def myFunc(apps, schema_editor): 
    MyModel = apps.get_model('myApp 'MyModel')

and then calling that function like so:

class Migration(migrations.Migration):
    operations = [
        migrations.RunPython(initialize_mhs, reverse_code=migrations.RunPython.noop),
    ]

Additionally the original import worked until I modified the model in a later migration, making this error harder to locate.

来源：https://stackoverflow.com/questions/42613536/django-programming-error-column-does-not-exist-even-after-running-migrations