OperationalError1075 'Incorrect table definition'

Question

I changed one of my models to go from

serial_number = models.BigIntegerField(unique=True)

to

serial_number = models.AutoField(primary_key=True)

and ran

$ python manage.py check -v 3
$ python manage.py makemigrations -v 2
$ python manage.py migrate -v 2

However, when I try to run the unit tests (which passed fine before), I get this error:

[...]
  File "/home/usr/Envs/intranet/lib/python2.7/site-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
    raise errorclass, errorvalue django.db.utils.OperationalError: (1075, 'Incorrect table definition; there can be only one auto column and it must be defined as a key')

How to resolve this?

Answer 1

The Error1075 'Incorrect table definition' came from Mysql, not Django. That is because the table u changed got 2 auto_created fields, while it is only one field alled allow for one table in Mysql.

In Django, just add a parm 'auto_created'：

serial_number = models.AutoField(primary_key=True， auto_created=False)

then remove u old migrations file last time and make migrations again, continue migrate will be ok.

Answer 2

So far the only "solution" was to trash all the migrations and re-create the database. Thus trashing all the old data. But it is less of a pain than fixing this craziness.