Database trouble in Django: can't reset because of dependencies - sql

Question

I'm trying to reset a database in Django, using:
python manage.py reset app
but get the following error:
Error: Error: app couldn't be reset. Possible reasons:
* The database isn't running or isn't configured correctly.
* At least one of the database tables doesn't exist.
* The SQL was invalid.
Hint: Look at the output of 'django-admin.py sqlreset app'. That's the SQL this command wasn't able to run.
The full error: cannot drop table app_record because other objects depend on it
HINT: Use DROP ... CASCADE to drop the dependent objects too.
This is what my models.py file looks like:
class Record(models.Model):
name = models.CharField(max_length=50, db_index=True)
year = models.IntegerField(blank=True, null=True)
def __unicode__(self):
return self.name
class Class(models.Model):
record = models.ForeignKey(Record)
def __unicode__(self):
return self.id
I get that I need to use the DROP... CASCADE command in the SQL that deletes and recreates the database (the output of django-admin.py).
But how can I edit that SQL directly from models.py?
UPDATE
OK, I figured out how to delete tables manually (the database is postgres), have noted it here for anyone with the same problem:
python manage.py dbshell
# drop table app_record cascade;
# \q
python manage.py reset app
Would still like to know if anyone has a better way to do it, though :)

Answer 1

The easy way to fully reset a Django database is using django-extensions.
It has a reset_db command that supports all Django's default database backends.
python manage.py reset_db
If you're using Django 1.2+ you should explicitly define the database you want to reset. If your project only uses one database, you should probably set --router=default

Answer 2

I use a little unix pipeline that adds CASCADE to all the DROP statements.
python manage.py sqlreset myapp | sed 's/DROP TABLE \(.*\);/DROP TABLE \1 CASCADE;/g' | \
psql --username myusername mydbname

Answer 3

The problem of DROP TABLE CASCADE is that it just remove a foreign keys on related tables - after syncdb this relation is not recreated.
I found no way to recreate the particular model's tables, so I'm reseting whole application by recreating schema:
DROP SCHEMA public CASCADE;
CREATE SCHEMA "public" AUTHORIZATION "owner of database";
That should work only with database that supports schema, e.g. postgresql

Answer 4

Using the details in other answers, I made a bash function that I dropped into ~/.bash_profile (on Mac OS X).
django_reset () { python mainsite/manage.py sqlreset "$*" | sed 's/DROP TABLE \(.*\);/DROP TABLE \1 CASCADE;/g' | mainsite/manage.py dbshell ; }
Then just run this command in the terminal from your root code directory (so the path to mainsite/manage.py makes sense).
django_reset myappA myappB
And it'll execute!

Answer 5

I found another way. I'm using sqlite3 that comes by default in Django.
To reset table to default.
python manage.py flush --database=default
after this you will need to use the syncdb command again.