UUIDFIeld(default=uuid.uuid4) created with migrations are the same

[afg984]

Steps to reproduce:

1. Create model

   class Bar(models.Model):
       pass
   

2. makemigrations & migrate

3. Create some Bar()s in the database

   >>> Bar.objects.create()
   <Bar: Bar object>
   >>> Bar.objects.create()
   <Bar: Bar object>
   >>> Bar.objects.create()
   <Bar: Bar object>
   >>> Bar.objects.create()
   <Bar: Bar object>
   

4. Add a UUIDField

   class Bar(models.Model):
       uu = models.UUIDField(default=uuid.uuid4)
   

5. makemigrations & migrate

if I use unique=True in the previous step, ./manage.py migrate gives me:
django.db.utils.IntegrityError: UNIQUE constraint failed: foo_bar__new.uu

6. The UUIDs are the same

   >>> [bar.uu for bar in Bar.objects.all()]
   [UUID('fae77227-7555-457d-a049-1e62e030ce1c'), UUID('fae77227-7555-457d-a049-1e62e030ce1c'), UUID('fae77227-7555-457d-a049-1e62e030ce1c'), UUID('fae77227-7555-457d-a049-1e62e030ce1c')]
   

Environment:

>>> platform.python_version()
'3.4.3'
>>> platform.platform()
'Linux-4.0.5-1-ARCH-x86_64-with-arch'
>>> django.__version__
'1.8.2'

[Tim Graham]

Please see ​how to write migrations that add unique fields.

#23408 suggests to add a warning to makemigrations for this case.

[afg984]

sorry for that, should have read it