For this exact reason I always use `sqlmigrate` to get the auto generated sql statement (and the backwards sql) and put this statements in `forwards` and `backwards` functions. I then separate the db and state operations.
I bet if you run `python manage.py sqlmigrate <app name> <migration>` on the migrations that removes the field from the model, you will see the sql that deletes the index. On Sat, Oct 5, 2024 at 8:02 AM Alan Evangelista <[email protected]> wrote: > I found out the cause was that I recently removed the max_documents field > in the Template model, Postgres automatically deletes a constraint when one > of the related columns is deleted and Django does not realize it. I > manually updated the Django migration that deleted the field to also > deleted the constrain and it worked fine. > > On Fri, Oct 4, 2024, 10:52 Alan Evangelista <[email protected]> wrote: > >> Hi, everyone. >> >> I have the following db model: >> >> class Template(models.Model): >> max_documents = models.PositiveIntegerField(default=1) >> is_comparison = models.BooleanField(default=False) >> ... >> class Meta: >> constraints = [ >> models.CheckConstraint( >> check=models.Q(is_comparison=False) | >> models.Q(max_documents__gte=2, is_comparison=True), >> name="is_comparison_requires_min_documents", >> ), >> ] >> >> I recently added this check constraint above and makemigrations created >> the following db migration: >> >> class Migration(migrations.Migration): >> dependencies = [ >> ... >> ] >> >> operations = [ >> migrations.AddConstraint( >> model_name="template", >> constraint=models.CheckConstraint( >> check=models.Q( >> ("is_comparison", False), >> models.Q(("is_comparison", True), >> ("max_documents__gte", 2)), >> _connector="OR", >> ), >> name="is_comparison_requires_min_documents", >> ), >> ), >> ] >> >> Today I deleted the constraint and ran makemigrations again, which >> created this second migration: >> >> class Migration(migrations.Migration): >> dependencies = [ >> ... >> ] >> >> operations = [ >> migrations.RemoveConstraint( >> model_name="template", >> name="is_comparison_requires_min_documents", >> ), >> ] >> >> When I try to run the 2nd migration, I get the following Postgres error >> from Django: >> django.db.utils.ProgrammingError: constraint >> "is_comparison_requires_min_documents" of relation "ai_template" does not >> exist >> >> I checked the ai_template table schema and confirmed there is no check >> constraint there. It seems to me Django didn't create the check constraint >> on the Postgres db side (maybe it was enforcing it on its side) and now is >> trying to remove it from Postgres. Is that a bug or am I missing something? >> >> Thanks in advance! >> >> -- >> > You received this message because you are subscribed to a topic in the >> Google Groups "Django users" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/django-users/VBkLU6AP9b4/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/django-users/8d16410d-ded2-4f2f-a457-675127825443n%40googlegroups.com >> <https://groups.google.com/d/msgid/django-users/8d16410d-ded2-4f2f-a457-675127825443n%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-users/CAKz%2BTUsu1BE9EzvUxPHfz8ND%2BWL3uA%2B0ZyM9jsWfG%2BektwUt_Q%40mail.gmail.com > <https://groups.google.com/d/msgid/django-users/CAKz%2BTUsu1BE9EzvUxPHfz8ND%2BWL3uA%2B0ZyM9jsWfG%2BektwUt_Q%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/CALmEK1uFCkmY%3DoYfsUsQRG%2BGR2YcF-4NvsSDOn%3DhrWYMB3vvQg%40mail.gmail.com.
