Migrations generates code that it can't execute

[Michael]

Migrations have been fine, until I rebuilt them to squash them down.

When I run makemigrations it generates this line of code:

bases=(core.djpp.permpp.PermissionsMixin_factory.<locals>.PermissionsMixin, models.Model, djpp.modelpp.NiceNameMixin),

Which when it tries to run falls over:

  File "/home/user/project/src/dist/app/plug/migrations/accounts/0001_initial.py", line 92
    bases=(core.djpp.permpp.PermissionsMixin_factory.<locals>.PermissionsMixin, models.Model, djpp.modelpp.NiceNameMixin),
    ^
SyntaxError: expression cannot contain assignment, perhaps you meant "=="?

Here is most of the migration, I left out some other operations:

# Generated by Django 4.0.1 on 2023-05-30 16:17

import accounts.models
import core.djpp.permpp
import django.contrib.auth.models
from django.db import migrations, models
import django.utils.timezone
import djpp.modelpp
import lib.timelib.ttb


class Migration(migrations.Migration):

    initial = True

    dependencies = [
        ('auth', '0012_alter_user_first_name_max_length'),
    ]

    operations = [
       ...,
        migrations.CreateModel(
            name='User',
            fields=[
                ('id', models.SmallAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('password', models.CharField(max_length=128, verbose_name='password')),
                ('last_login', models.DateTimeField(blank=True, null=True, verbose_name='last login')),
                ('is_superuser', models.BooleanField(default=False, help_text='Designates that this user has all permissions without explicitly assigning them.', verbose_name='superuser status')),
                ('first_name', models.CharField(blank=True, max_length=150, verbose_name='first name')),
                ('last_name', models.CharField(blank=True, max_length=150, verbose_name='last name')),
                ('is_active', models.BooleanField(default=True, help_text='Designates whether this user should be treated as active. Unselect this instead of deleting accounts.', verbose_name='active')),
                ('date_joined', models.DateTimeField(default=django.utils.timezone.now, verbose_name='date joined')),
                ('email', models.EmailField(max_length=254, unique=True, verbose_name='email address')),
                ('is_staff', models.BooleanField(default=False, help_text='Designates whether the user can log into this admin site.', verbose_name='admin access')),
                ('groups', models.ManyToManyField(blank=True, help_text='The groups this user belongs to. A user will get all permissions granted to each of their groups.', related_name='user_set', related_query_name='user', to='auth.Group', verbose_name='groups')),
                ('user_permissions', models.ManyToManyField(blank=True, help_text='Specific permissions for this user.', related_name='user_set', related_query_name='user', to='auth.Permission', verbose_name='user permissions')),
            ],
            options={
                'db_table': 'auth_user',
            },
            bases=(core.djpp.permpp.PermissionsMixin_factory.<locals>.PermissionsMixin, models.Model, djpp.modelpp.NiceNameMixin),
            managers=[
                ('objects', accounts.models.UserManager()),
            ],
        ),
    ]

In Django's defense it is quite a convoluted iheritance chain for the user model, that looks like this:

#permpp.py - permission mixin factory which the user model inherits from
def PermissionsMixin_factory(group_roles: GroupRoles, user_perms: UserPerms) -> type:
    class PermissionsMixin:
        def __init__(self, *args, **kwargs):
            super().__init__(*args, **kwargs)
            # user.has_perm is built into Django, call ours user.permissions
            setattr(self, GETTER_ATTR, PermissionGetter(self, group_roles, user_perms))

        @property
        def cached_groups(self):
              print('cached_group things')

    return PermissionsMixin

PermissionsMixin = permpp.PermissionsMixin_factory(grs, ups)

#perm.py - Constructs the permission mixin
from core.djpp import permpp
...

PermissionsMixin = permpp.PermissionsMixin_factory(...)

#app/plug/user.py - mixin for customising user model for this project
from django.db import models
from .perm import PermissionsMixin

class UserMixin(PermissionsMixin, models.Model):
    class Meta:
        abstract = True

    @property
    def foo(self):
        return 'foo'

#accounts/user.py - define the user model
class User(UserMixin, AbstractUser, modelpp.NiceNameMixin):
    """
    Requirements:
    - Must be defined in models.py, due to the way settings.AUTH_USER_MODEL is defined
    """

    objects = UserManager()

    username = None
    email = models.EmailField('email address', unique=True)
    is_staff = models.BooleanField(
        'admin access',
        default=False,
        help_text='Designates whether the user can log into this admin site.',
    )

    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = ('first_name',)

    def __str__(self):
        return self.get_full_name()

    class Meta:
        db_table = 'auth_user'

    #Other of custom methods ...

[Michael]

Changing this line from:

bases=(core.djpp.permpp.PermissionsMixin_factory.<locals>.PermissionsMixin, models.Model, djpp.modelpp.NiceNameMixin),

to:

bases=(models.Model, djpp.modelpp.NiceNameMixin),

Make it work fine, since PermissionsMixin does not define any DB fields, is just run time behavior, but I thought this issue might highlight an underlying problem.

[Natalia Bidart]

Hello!

First of all, please note that you are using a version of Django that is no longer supported (4.0.1).
Secondly, the error seems to be caused by either:

1. a possible misconfiguration/bug in your code, or
2. the result from squashing the migrations is somehow invalid.

For the first case, the recommended approach is to first ensure whether the error you are getting is a bug in Django itself, or not in your code. To do that, you can follow ​the bug reporting guide and seek help in the Django User channels to evaluate whether your problem is caused by a configuration issue.

For the second case, we would need a minimal example of two working migrations and their minimal models that, when squashed, would generate the invalid result. It's important to try to narrow the models and migrations to the bare minimum that triggers the issue, and that what's shared in the bug is fully functional. At the very least we'd need the migrations that were squashed down to the result you pasted in this report.

Closing this ticket as invalid for now, but if you find a concrete bug in Django itself or if you can provide a reproducer for the faulty squashed migration, please let us know and we'll analyze this further. Thanks!