Programmatically create a django group with permissions

Question

In the Admin console, I can add a group and add a bunch of permissions that relate to my models, e.g.

api | project | Can add project
api | project | Can change project
api | project | Can delete project

How can I do this programmatically. I can't find any information out there on how to do this.

I have:

from django.contrib.auth.models import Group, Permission
from django.contrib.contenttypes.models import ContentType

from api.models import Project


new_group, created = Group.objects.get_or_create(name='new_group')
# Code to add permission to group ???
ct = ContentType.objects.get_for_model(Project)
# Now what - Say I want to add 'Can add project' permission to new_group?

UPDATE: Thanks for the answer you provided. I was able to use that to work out what I needed. In my case, I can do the following:

new_group, created = Group.objects.get_or_create(name='new_group')
proj_add_perm = Permission.objects.get(name='Can add project')
new_group.permissions.add(proj_add_perm)

Answer 1

Use below code

from django.contrib.auth.models import Group, Permission
from django.contrib.contenttypes.models import ContentType
from api.models import Project
new_group, created = Group.objects.get_or_create(name='new_group')
# Code to add permission to group ???
ct = ContentType.objects.get_for_model(Project)

# Now what - Say I want to add 'Can add project' permission to new_group?
permission = Permission.objects.create(codename='can_add_project',
                                   name='Can add project',
                                   content_type=ct)
new_group.permissions.add(permission)

Answer 2

I needed to create a default set of groups and permission (view only) for those groups. I came up with a manage.py command that may be useful to others (create_groups.py). You can add it to your <app>/management/commands dir, and then run via manage.py create_groups:

"""
Create permission groups
Create permissions (read only) to models for a set of groups
"""
import logging

from django.core.management.base import BaseCommand
from django.contrib.auth.models import Group
from django.contrib.auth.models import Permission

GROUPS = ['developers', 'devops', 'qa', 'operators', 'product']
MODELS = ['video', 'article', 'license', 'list', 'page', 'client']
PERMISSIONS = ['view', ]  # For now only view permission by default for all, others include add, delete, change


class Command(BaseCommand):
    help = 'Creates read only default permission groups for users'

    def handle(self, *args, **options):
        for group in GROUPS:
            new_group, created = Group.objects.get_or_create(name=group)
            for model in MODELS:
                for permission in PERMISSIONS:
                    name = 'Can {} {}'.format(permission, model)
                    print("Creating {}".format(name))

                    try:
                        model_add_perm = Permission.objects.get(name=name)
                    except Permission.DoesNotExist:
                        logging.warning("Permission not found with name '{}'.".format(name))
                        continue

                    new_group.permissions.add(model_add_perm)

        print("Created default group and permissions.")

UPDATE: A bit more sophisticated now:

from django.contrib.auth.models import Group
from django.contrib.auth.models import User
from django.contrib.auth.models import Permission
from django.contrib.contenttypes.models import ContentType


READ_PERMISSIONS = ['view', ]  # For now only view permission by default for all, others include add, delete, change
WRITE_PERMISSIONS = ['add', 'change', 'delete']
EMAIL_USER_DOMAIN = 'your-domain.com'

# Add your groups here, app and model code
GROUP_MODEL = ('auth', 'group')
USER_MODEL = ('auth', 'user')
PERMISSION_MODEL = ('auth', 'permission')
LOG_ENTRY_MODEL = ('admin', 'logentry')


def add_group_permissions(group_names, model_natural_keys, permissions):
    """
    Add permissions to the provided groups for the listed models.
    Error raised if permission or `ContentType` can't be found.

    :param group_names: iterable of group names
    :param model_natural_keys: iterable of 2-tuples containing natural keys for ContentType
    :param permissions: iterable of str (permission names i.e. add, view)
    """
    for group_name in group_names:
        group, created = Group.objects.get_or_create(name=group_name)

        for model_natural_key in model_natural_keys:
            perm_to_add = []
            for permission in permissions:
                # using the 2nd element of `model_natural_key` which is the
                #  model name to derive the permission `codename`
                permission_codename = f"{permission}_{model_natural_key[1]}"
                try:
                    perm_to_add.append(
                        Permission.objects.get_by_natural_key(
                            permission_codename, *model_natural_key
                        )
                    )
                except Permission.DoesNotExist:
                    # trying to add a permission that doesn't exist; log and continue
                    logging.error(
                        f"permissions.add_group_permissions Permission not found with name {permission_codename!r}."
                    )
                    raise
                except ContentType.DoesNotExist:
                    # trying to add a permission that doesn't exist; log and continue
                    logging.error(
                        "permissions.add_group_permissions ContentType not found with "
                        f"natural name {model_natural_key!r}."
                    )
                    raise

            group.permissions.add(*perm_to_add)


def set_users_group(users, group):
    """
    Adds users to specific permission group.
    If user or group does not exist, they are created.
    Intended for use with special users for api key auth.
    :param users: list of str, usernames
    :param group: str, group for which users should be added to
    :return: list, user objects added to group
    """
    users = users or []
    user_objs = []
    for user_name in users:
        try:
            user = User.objects.get(username=user_name)
        except User.DoesNotExist:
            user = User.objects.create_user(username=user_name,
                                            email=f'{user_name}@{EMAIL_USER_DOMAIN}',
                                            password='')
        user_objs.append(user)
        group, created = Group.objects.get_or_create(name=group)
        group.user_set.add(user)

    return user_objs


API_READ_GROUP = 'api-read-users'
API_WRITE_GROUP = 'api-write-users'
READ_GROUPS = [API_READ_GROUP, ]
WRITE_GROUPS = [API_WRITE_GROUP, ]  # Can be used in same way as read users below

# Adding users to a group
set_users_group(READ_USERS, API_READ_GROUP)

# Setting up the group permissions i.e. read for a group of models
add_group_permissions(READ_GROUPS, [GROUP_MODEL, USER_MODEL, LOG_ENTRY_MODEL], READ_PERMISSIONS)

I also found that using manage.py update_permissions is useful to sort out/clean up stale permissions if models have changed etc.. Its part of django-extensions commands.

Answer 3

Inspired by radtek's answer I created a bit better version (in my opinion). It allows specifying model as object (instead of string) and specifying all configuration in one dictionary (instead of several lists)

# backend/management/commands/initgroups.py
from django.core.management import BaseCommand
from django.contrib.auth.models import Group, Permission

from backend import models

GROUPS_PERMISSIONS = {
    'ConnectionAdmins': {
        models.StaticCredentials: ['add', 'change', 'delete', 'view'],
        models.NamedCredentials: ['add', 'change', 'delete', 'view'],
        models.Folder: ['add', 'change', 'delete', 'view'],
        models.AppSettings: ['view'],
    },
}

class Command(BaseCommand):
    def __init__(self, *args, **kwargs):
        super(Command, self).__init__(*args, **kwargs)

    help = "Create default groups"

    def handle(self, *args, **options):
        # Loop groups
        for group_name in GROUPS_PERMISSIONS:

            # Get or create group
            group, created = Group.objects.get_or_create(name=group_name)

            # Loop models in group
            for model_cls in GROUPS_PERMISSIONS[group_name]:

                # Loop permissions in group/model
                for perm_index, perm_name in \
                        enumerate(GROUPS_PERMISSIONS[group_name][model_cls]):

                    # Generate permission name as Django would generate it
                    codename = perm_name + "_" + model_cls._meta.model_name

                    try:
                        # Find permission object and add to group
                        perm = Permission.objects.get(codename=codename)
                        group.permissions.add(perm)
                        self.stdout.write("Adding "
                                          + codename
                                          + " to group "
                                          + group.__str__())
                    except Permission.DoesNotExist:
                        self.stdout.write(codename + " not found")