Can not use django migrations to rename field.

[luoxiaopeng]

1. Create a demo project(eg. mysite, https://docs.djangoproject.com/en/4.0/intro/tutorial01/)
2. Change models.py and migrations(No problem)

from django.db import models
from sortedm2m.fields import SortedManyToManyField

class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')
    choice_order = SortedManyToManyField("Choice", related_name='choice_order', blank=True)

class Choice(models.Model):
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

3. Make some data for Question and Choice.
4. change choice_order to choices (models.py)
5. python3 manage.py makemigrations (will generate something like this migrations.RenameField(
   model_name='question',
   old_name='choice_order',
   new_name='choices',
   ))
6. python3 manage.py migrate
7. django.db.utils.IntegrityError: NOT NULL constraint failed: polls_question_choices.sort_value

I don't know how to contact you and I alse don't know whether django-sortedm2m support migrations.RenameField.
Could you have a look this problem when you're free.
Thank you

[luoxiaopeng]

Maybe I need to change sort_value_field_name

[AlanCoding]

I tried to replicate this in a branch here:

https://github.com/AlanCoding/django-sortedm2m/compare/test_project_41...AlanCoding:django-sortedm2m:rename_field_migration?expand=1

Doing this properly requires migrating, running the server, creating data, switching to this branch, and then migrating just the new migration. Currently, there are a lot of migration tests but they don't seem to create data, so it wouldn't be a fair comparison to what you did.

This tells me that I cannot reproduce your error. The cars field definition is in this repo, and you can see that it doesn't set a related_name or a sort_value. I haven't tried toggling those.

I'm testing with postgres and 4.1.7

[AlanCoding]

python3 manage.py makemigrations

Also, it doesn't automatically pick up a RenameField for me. The generated migration for me deletes the relationship and adds a new one. That's fine, Django isn't smart enough to understand it was renamed. I manually had to put in the RenameField.

Maybe you mixed up new_name / old_name? I don't have enough information to tell.