#23978: Migrations call callable field defaults only once for all rows
-------------------------------+--------------------
Reporter: rowanseymour | Owner: nobody
Type: Bug | Status: new
Component: Uncategorized | Version: 1.7
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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If you add a field with a callable default to an existing model, e.g.
{{{
def generate_uuid():
return unicode(uuid4())
class Foo(models.Model):
uuid = models.CharField(max_length=36, unique=True,
default=generate_uuid)
}}}
You'll get a migration like...
{{{
migrations.AddField(
model_name='foo',
name='uuid',
field=models.CharField(default=foo.models.generate_uuid,
max_length=36, unique=True),
preserve_default=True,
),
}}}
The default function is called only once to get a single default value for
all rows, which in this case will fail because the column has a unique
constraint.
--
Ticket URL: <https://code.djangoproject.com/ticket/23978>
Django <https://code.djangoproject.com/>
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