Where do I create groups?

Using Django Mystery Errors
1

I need to create certain groups before users start using my app. I was thinking adding it to my models.py, but that creates a runtime warning about accessing the database while AppConfig.ready()/import modules (self.APPS_NOT_READY_WARNING_MSG). So, I’m thoughtfully confused about when is the right time to create groups. Do I need a setup process that creates them within a view? What happens when I need to add more groups? I really want to avoid downstream users creating groups, because the application is complicated as it is with certain permissions that only make sense in conjunction.

2

You’ve got at least four places I can think of off-hand where you could create groups. (Your choice among them depends upon how and when you need to do this.)

3

I presume that the same applies to custom permissions, or are those allowed to be on the codebase?

4

Correct. As a general rule, you don’t want to do any ORM-related work during Django startup.

5

I decided for the data migration path, since it can be part of the deployment without needing to specify extra steps:

I will have a migration like this:

def create_new_permissions_for_user(apps, schema_editor):
    ContentType = apps.get_model("contenttypes", "contenttype")
    user_type = ContentType.objects.get(app_label="auth", model="user")
    Permission = apps.get_model("auth", "Permission")

    Permission.objects.create(codename="view_self_user", name="Can view its own user", content_type=user_type)
    
    

class Migration(migrations.Migration):

    dependencies = [
        ("user_management", "0001_initial"),
        ("auth", "0012_alter_user_first_name_max_length"),
    ]

    operations = [migrations.RunPython(create_new_permissions_for_user)]

This seems “ok” considering that:

  1. I have no guarantee that anything exist in the order I say it would exists, therefore I need to add that “auth” dependency before everything else.
  2. There are two ways to access ContentType, I decided to not import directly the model from the system, but to leverage as much as possible how data migrations are supposed to be done. Is this unnecessary?
6

The dependency chain is transitive. If your user_management.0001_initial has a dependency on that auth.0012 migration, and your current migration depends upon user_management.0001, then you don’t need to add the auth.0012 as a dependency here.

For these models? Yes. The purpose of the apps.get_model is to protect this migration from the model-as-defined-in-models.py not matching the model-as-it-currently-exists-in-the-database situation that occurs when changes are being made to the models. In my opinion, it’s highly unlikely that either of these models are going to change in a way to invalidate this code.