Tony Kyriakidis Tony Kyriakidis - 6 months ago 16
SQL Question

django.db.utils.IntegrityError: column "venue_city" contains null values

I have read a lot of other posts here on stackoverflow and google but I could not find a solution.

It all started when I changed the model from a CharField to a ForeignKey.
The error I recieve is:

Operations to perform:
Synchronize unmigrated apps: gis, staticfiles, crispy_forms, geoposition, messages
Apply all migrations: venues, images, amenities, cities_light, registration, auth, admin, sites, sessions, contenttypes, easy_thumbnails, newsletter
Synchronizing apps without migrations:
Creating tables...
Running deferred SQL...
Installing custom SQL...
Running migrations:
Rendering model states... DONE
Applying venues.0016_auto_20160514_2141...Traceback (most recent call last):
File "/Users/iam-tony/.envs/venuepark/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
psycopg2.IntegrityError: column "venue_city" contains null values


My model is as follows:

class Venue(models.Model):
venue_city = models.ForeignKey(City, null=True,)
venue_country=models.ForeignKey(Country, null=True)


venue_country did not exist before so that migration happened successfully. But venue_city was a CharField.

I made some changes to my migration file so that it would execute the sql as follows:

# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import migrations, models


class Migration(migrations.Migration):

dependencies = [
('venues', '0011_venue_map_activation'),
]

migrations.RunSQL(''' ALTER TABLE venues_venue ALTER venue_city TYPE integer USING venue_city::integer '''),

migrations.RunSQL(''' ALTER TABLE venues_venue ALTER venue_city RENAME COLUMN venue_city TO venue_city_id '''),

migrations.RunSQL(''' ALTER TABLE venues_venue ADD CONSTRAINT venues_venus_somefk FOREIGN KEY (venue_city_id) REFERENCES cities_light (id) DEFERRABLE INITIALLY DEFERRED'''),


Thanks in advance!

UPDATE: my new migration file:

# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import migrations, models


class Migration(migrations.Migration):

dependencies = [
('cities_light', '0006_compensate_for_0003_bytestring_bug'),
('venues', '0024_remove_venue_venue_city'),
]

operations = [
migrations.AddField(
model_name='venue',
name='venue_city',
field=models.ForeignKey(null=True, to='cities_light.City'),
),
]

Answer

Looks like you added null=True after created migration file. Because venue_city is not a nullable field in your migration file

Follow these steps.

1) Drop venue_city & venue_country from your local table
3) Delete all the migration files you created for these `CharField to a ForeignKey` change
4) execute `python manage.py makemigrations`
5) execute 'python manage.py migrate'

It should work