django: data migrate permissions

Question

I have a bunch of new permissions which I need to migrate. I tried doing it through data migration but complains about ContentType not being available.

Doing quick research I found out that ContentType table is populated after all the migrations applied.

I even tried using update_all_contenttypes() from from django.contrib.contenttypes.management import update_all_contenttypes which causes migration to load data which is not consistent to the fixture.

What is the best way to migrate permission data in Django?

Rudderpost

Can you paste your models and migration? – Chime

I have the same problem. Migration looks like this: pastebin.com/avmfXHmY ; INSTALLED_APPS = ('svsite', ..., 'django.contrib.contenttypes', '...', 'member') and the user just extends AbstractUser. – Lection

It seems it would fail for anything though. All Permissions need ContentType instances, which don't exists during migration... – Lection

Some interesting issues: code.djangoproject.com/ticket/23422, code.djangoproject.com/ticket/29843 – Battlement

Answer 1

There are 2 ways to solve this:

1) The ugly way:

Run manage.py migrate auth before your wanted migration

2) Recommended way:

from django.contrib.auth.management import create_permissions

def add_permissions(apps, schema_editor):
    apps.models_module = True

    create_permissions(apps, verbosity=0)
    apps.models_module = None

    # rest of code here....

Viridi

Also see source for django.contrib.auth.management.create_permissions – Battlement

Answer 2

Here is a quick and dirty way to ensure all permissions for all apps have been created:

def add_all_permissions(apps=None, schema_editor=None):
    from django.contrib.auth.management import create_permissions

    if apps is None:
        from django.apps import apps

    for app_config in apps.get_app_configs():
        app_config.models_module = True
        create_permissions(app_config, verbosity=0)
        app_config.models_module = None

class Migration(migrations.Migration):
    dependencies = [('myapp', '0123_do_the_thing')]
    operations = [
        migrations.RunPython(add_all_permissions, 
                             reverse_code=migrations.RunPython.noop)
        # ...
    ]

NOTE: edited to include ruohola's excellent suggestion

Andro

Where would you add this? – Durstin

This would go in a data migration (anywhere in the file) and get called at the beginning of a RunPython method – Andro

Better to make it so def add_all_permissions(apps, schema_editor):, and then there is no need to import apps. Then one can just use migrations.RunPython(code=add_all_permission). – Behre

Answer 3

Here are steps for adding custom permissions to the User model:

First create a migration file, for example under your authentication application,

Here i named it 0002_permission_fixtures.py:

account (your authentication application)
 |_migrations
   |__ 0001_initial.py
   |__ 0002_permission_fixtures.py
   |__ __init__.py

Then adding your permission objects, as follow:

# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import migrations


def forwards_func(apps, schema_editor):
    # Get models that we needs them
    user = apps.get_model("auth", "User")
    permission = apps.get_model("auth", "Permission")
    content_type = apps.get_model("contenttypes", "ContentType")
    # Get user content type object
    uct = content_type.objects.get_for_model(user)
    db_alias = schema_editor.connection.alias
    # Adding your custom permissions to User model: 
    permission.objects.using(db_alias).bulk_create([
        permission(codename='add_sample', name='Can add sample', content_type=uct),
        permission(codename='change_sample', name='Can change sample', content_type=uct),
        permission(codename='delete_sample', name='Can delete sample', content_type=uct),
    ])


class Migration(migrations.Migration):
    dependencies = [
    ('contenttypes', '__latest__'),
            ]

    operations = [
        migrations.RunPython(
            forwards_func,
        ),
    ]

To run this migration, first migrate contenttype model, and then migrate your application (here is account).

$ python manage.py migrate contenttypes
$ python manage.py migrate account

Ploy

Wouldn't it be better to use "Sample" content type as opposed to User content type? – Grass