Django Programming error column does not exist even after running migrations

Question

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?¡?

Answer 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.

Answer 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.

Answer 3

Here's what i tried and it worked:

• Go and add manually the column to your table
• run python manage.py makemigrations
• go back drop that column you added
• run python manage.py migrate

Answer 4

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.

Answer 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.

Answer 6

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.

Answer 7

The issue was in the Models for me, for some reason Django was adding '_id' to the end of my Foreign Key column. I had to explicitly set the related named to the Foreign Key. Here 'Cards' is the parent table and 'Prices' is the child table.

class Cards(models.Model):
    unique_id = models.CharField(primary_key=True, max_length=45)
    name = models.CharField(max_length=225)   

class Prices(models.Model):
        unique_id = models.ForeignKey(Cards, models.DO_NOTHING)

Works after changing to:

class Cards(models.Model):
    unique_id = models.CharField(primary_key=True, max_length=45)
    name = models.CharField(max_length=225)   

class Prices(models.Model):
        unique_id = models.ForeignKey(Cards, models.DO_NOTHING, db_column='unique_id')

Answer 8

When I get this error, my extreme way to solve it is to reset my database:

1. Reset your database

For Postgresql on Heroku:

Heroku > your_app > Resources > database > add-ons > click on your database and open it

For postgresql

settings > Reset database

2. Delete all files in your_app > migrations > __pycache__ except __init.py__
3. Delete all files in your_app > migrations except __pycache__ folder and __init.py__

4. Then run:

   python manage.py makemigrations

   python manage.py migrate

   python manage.py createsuperuser

type in to create your superuser, then run:

python manage.py makemigrations

python manage.py migrate

python manage.py 

If you are able to inspect your models from your admin section, then it should be all okay now.

Answer 9

Just remove corresponding row migrations for that model in 'django_migrations' model in database.

And re run python manage.py migrate app_name

Answer 10

I tried all these answers with not much luck! What I did to have this problem solved with no harm was to go back through the migration files and find where the actual model was being created for the first time then manually add the field (in the column not being existed error message). Until if you run makemigrations --dry-run you get/see "No changes detected" and that worked. Basically, in my case, I had to carefully take my desired db changes back in time in proper migration file, rather creating a new migration now at the end of migration dependency chain.

Answer 11

What helped me in the end was simply dropping the database and creating it again as well as deleting all migrations files (including cache). (only removing migrations file didn't work for me at all)

sudo su - postgres
psql
DROP DATABASE 'yourdatabase';
CREATE DATABASE 'yourdatabase';
GRANT ALL PRIVILEGES ON DATABASE 'yourdatabase' to 'yourdjangouser';

then just

python manage.py makemigrations
python manage.py migrate
python manage.py runserver

Answer 12

1. Open the latest py file created after running the makemigrations command inside migrations folder of that particular app.
2. Inside class Migration there is a list attribute called 'operations'.
3. Remove the particular elements migrations.RemoveField(...).
4. Save and run python manage.py migrate.

Answer 13

A easier solution to the problem is to make your models exactly like it is in the migration first. and run python manage.py migrate.

Then revert those changes

Run

python manage.py makemigrations
python manage.py migrate

To check for which migrations are applied and which are not, use -:

python manage.py showmigrations

Answer 14

I solved a similar problem by deleting all migrations files (Don't forget to make a backup) and python manage.py makemigrations all of them into one clean file in development and pulling new files on the server. Before then I had dropped existing tables on the PostgreSQL.

Answer 15

If you're in development and you make some examples of data that's not important, this step is beneficial for me: just flush your data, make migrations, and migrate:

• python manage.py flush
• python manage.py makemigrations
• python manage.py migrate

After that, you may create a new database from scratch, I hope this information was helpful.