right way to create a django data migration that creates a group?

问题

I would like to create data migrations that create Permissions and Groups, so that my other developers can just run the migrations and get everything set up. I was able to create the migrations and run them just fine, but now I'm getting an error when running my tests.

But if I do this:

from django.contrib.auth.models import Group

def add_operations_group(apps, schema_editor):
    Group.objects.get_or_create(name='operations')

I get:

django.db.utils.OperationalError: no such table: auth_group

If I do this:

def add_operations_group(apps, schema_editor):
    Group = apps.get_model("django.contrib.auth", "group")
    Group.objects.get_or_create(name='operations')

I get:

LookupError: No installed app with label 'django.contrib.auth'

Is there a way to do this? Or is there a "Django Way" to make sure things like permissions and groups are created?

回答1:

This is how I do it:

from django.db import models, migrations


def apply_migration(apps, schema_editor):
    Group = apps.get_model('auth', 'Group')
    Group.objects.bulk_create([
        Group(name=u'group1'),
        Group(name=u'group2'),
        Group(name=u'group3'),
    ])


def revert_migration(apps, schema_editor):
    Group = apps.get_model('auth', 'Group')
    Group.objects.filter(
        name__in=[
            u'group1',
            u'group2',
            u'group3',
        ]
    ).delete()


class Migration(migrations.Migration):

    dependencies = [
        ('someapp', 'XXXX_some_migration'),
    ]

    operations = [
        migrations.RunPython(apply_migration, revert_migration)
    ]

Although, there must be a more Djangonic way.

回答2:

Answer from César is correct. To make it more Django create the migration file automatically by going to your django app root folder and entering:

python manage.py makemigrations <yourappname> --empty

Note: You may need python3 instead of python depending on your system configuration.

This creates an empty migration file in a sub directory of your app called 0001_initial.py

You can then alter it as per César instructions. Which worked correctly with Django 2.2

来源：https://stackoverflow.com/questions/33485464/right-way-to-create-a-django-data-migration-that-creates-a-group

标签

django

django-migrations