I have one model in my app running in a server with a few entries. I need to add a SlugField
, unique and not-null for this model. The SlugField
will be populated based on trading_name
. I've changed my model in order to add this new field and modified save method:
class Supplier(StatusModel):
SLUG_MAX_LENGTH = 210
slug = models.SlugField(unique=True, max_length=SLUG_MAX_LENGTH)
trading_name = models.CharField(max_length=200, verbose_name=_('trading name'))
...
def save(self, *args, **kwargs):
self.slug = orig = slugify(self.trading_name)[:Supplier.SLUG_MAX_LENGTH]
for x in itertools.count(1):
if not Supplier.objects.filter(slug=self.slug).exists():
break
# Truncate the original slug dynamically. Minus 1 for the hyphen.
self.slug = "%s-%d" % (orig[:Supplier.SLUG_MAX_LENGTH - len(str(x)) - 1], x)
self.full_clean()
super(Supplier, self).save(*args, **kwargs)
After changing the model, I've run manage.py makemigrations
and got this migration as output:
class Migration(migrations.Migration):
dependencies = [
('opti', '0003_auto_20141226_1755'),
]
operations = [
migrations.AddField(
model_name='supplier',
name='slug',
field=models.SlugField(unique=True, default='', max_length=210),
preserve_default=False,
),
]
I can't run manage.py migrate
because the default value wont work due to the unique constrant.
My question is: How can I do this with Django 1.7? I need to apply the schema change and keep the current entries in my database.
Unfortunatelly, I found no answer but I could create one solution: