[Django]-./manage.py test results in django.db.utils.OperationalError: no such column: MyNewColumn

by

5👍

✅

The problem is that the Ticket_generateUniqueID method used to get the default value is attempting to fetch a column that the migration has not created yet. 

try:
    t = Ticket.objects.get(ticket_number=retval)
    pass
except ObjectDoesNotExist:
    return retval

In this case, I think you can avoid the problem by changing your method to use exists() instead of get().

if Ticket.objects.filter(ticket_number=retval).exists():
    pass
else:
    return retval

If it wasn’t possible to rewrite the default method, then it would be trickier to fix. I believe that you would have to add a data migration before the migration that is causing the errors, and set the field values there. In the data migration, you could use Ticket = apps.get_model('myapp', 'Ticket'). You would then be able to run Ticket.objects.get() without any errors.

👤Alasdair

0👍

Just one update: when I deleted all migrations and recreated them as one simple, my tests starts to fail with:

django.db.utils.OperationalError: no such table: tickets_ticket

as my tests created (and not saved) Ticket objects before loading fixture with data so I added this sanity test before the while cycle:

if not( u'tickets_ticket' in connection.introspection.table_names()):
    return generateID() # if no table exists, none ID exists too, so anything is unique :)
# --- now find unique value
👤gilhad

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