id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
30526	migration to UUID id field doesn't properly convert integers (SQLite).	Martin Baker	nobody	"This may be present in other DBs, but I've noticed it with SQLite under Django 2.2.1.

Steps to reproduce:

1. Start a model with an implicit integer id, and create and run the migration:

{{{#!python
from django.db import models

class Something(models.Model):
    name = models.CharField(max_length=32)
}}}

2. Then create one instance via the shell (`python manage.py shell`):

{{{#!python
from uuidbug.models import Something
s = Something(name=""One"")
s.save()
}}}

In the DB it looks like this (can use `python manage.py dbshell`):
{{{
sqlite> .headers on
sqlite> select * from uuiditem_something;
name|id
One|1
}}}

3. Edit the model to use UUIDs:

{{{#!python
import uuid

from django.db import models

class Something(models.Model):
    name = models.CharField(max_length=32)
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
}}}

4. After creating and running the migration, add another instance:

{{{#!python
from uuidbug.models import Something
s = Something(name=""After UUID-ization"")
s.save()
}}}

DB now looks like this:

{{{
sqlite> select * from uuidbug_something;
name|id
One|1
After UUID-ization|693e1942d7d142289bb9fb3664f2c11a
}}}

Note that the id for the first instance has not been converted to a UUID properly. If you try to access the objects, you get an error:

{{{#!python
>>> Something.objects.all()
Traceback (most recent call last):
  File ""<console>"", line 1, in <module>
  File ""/Users/martin/Connery/opencc-backend/venv/lib/python3.7/site-packages/django/db/models/manager.py"", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File ""/Users/martin/Connery/opencc-backend/venv/lib/python3.7/site-packages/django/db/models/query.py"", line 653, in first
    for obj in (self if self.ordered else self.order_by('pk'))[:1]:
  File ""/Users/martin/Connery/opencc-backend/venv/lib/python3.7/site-packages/django/db/models/query.py"", line 274, in __iter__
    self._fetch_all()
  File ""/Users/martin/Connery/opencc-backend/venv/lib/python3.7/site-packages/django/db/models/query.py"", line 1242, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File ""/Users/martin/Connery/opencc-backend/venv/lib/python3.7/site-packages/django/db/models/query.py"", line 72, in __iter__
    for row in compiler.results_iter(results):
  File ""/Users/martin/Connery/opencc-backend/venv/lib/python3.7/site-packages/django/db/models/sql/compiler.py"", line 1044, in apply_converters
    value = converter(value, expression, connection)
  File ""/Users/martin/Connery/opencc-backend/venv/lib/python3.7/site-packages/django/db/backends/sqlite3/operations.py"", line 294, in convert_uuidfield_value
    value = uuid.UUID(value)
  File ""/usr/local/Cellar/python/3.7.3/Frameworks/Python.framework/Versions/3.7/lib/python3.7/uuid.py"", line 160, in __init__
    raise ValueError('badly formed hexadecimal UUID string')
ValueError: badly formed hexadecimal UUID string
}}}

"	Bug	closed	Migrations	dev	Normal	invalid	UUID		Unreviewed	0	0	0	0	0	0