Django 2.2 and later
As of version 2.2 Django supports declarative partial unique indexes on databases that support them (PostgreSQL and SQLite). So you could do something like:
from django.db.models import Model, Q, UniqueConstraint
class Post(Model):
...
class Meta:
constraints = [
UniqueConstraint(
fields=["title", "blog", "category"],
name="idx1",
condition=Q(category__isnull=False)),
UniqueConstraint(
fields=["title", "blog"],
name="idx2",
condition=Q(category__isnull=True)),
]
Django 2.1 and earlier
In older versions you need to do this with migrations. First create a new, empty migration file:
python manage.py makemigrations --empty yourappname
Then, for each index add an appropriate RunSQL
line:
operations = [
migrations.RunSQL("CREATE UNIQUE INDEX..."),
migrations.RunSQL("CREATE UNIQUE INDEX..."),
]
Finally, run migrate
.