Django: Inherit Permissions from abstract models?

Question

Is it possible to inherit permissions from an abstract model in Django? I can not really find anything about that. For me this doesn't work!

class PublishBase(models.Model): 
    class Meta:
        abstract = True
        get_latest_by = 'created'
        permissions = (('change_foreign_items',
                        "Can change other user's items"),)

EDIT: Not working means it fails silently. Permission is not created, as it wouldn't exist on the models inheriting from this class.

Answer 1

Here is link for resolve you issue: http://code.djangoproject.com/ticket/10686 Need to apply patch... But it realy works.

Answer 2

The permissions are not inherited, if the child class also defines its own class Meta. I found the following work-around, which saves from having to define the permissions again on every child model:

class AbstractBaseModel(models.Model):
    class Meta:
        abstract = True
        permissions = (("test_permission","test permission"),)


class SomeClass(AbstractBaseModel):
    name = models.CharField(max_length=255,verbose_name="Name")

    class Meta(AbstractBaseModel.Meta):
        verbose_name = ....

No need to set abstract to false in the child Meta class, since Django sets it in the parent to False when processing it! http://docs.djangoproject.com/en/dev/topics/db/models/#meta-inheritance

Answer 3

My work-around:

class AbstractModelBase(models.base.ModelBase):

    def __new__(cls, name, bases, attrs):
        new = super(AbstractModelBase, cls).__new__(cls, name, bases, attrs)
        new._meta.permissions += (("abstract_permission", "Abstract permission"),)
        return new


class AbstractModel(models.Model):
    __metaclass__ = AbstractModelBase

    class Meta:
        abstract = True

Answer 4

take a look at the following meta implementation, it adds read permissions to all django models that set MyModelMeta Class to be thier metaclass:

class MyModelMeta(ModelBase):
    # add a read permission to each MyModelMeta model
    def __new__(cls, name, bases, attrs):

        Meta = None

        if "Meta" in attrs:
            Meta = attrs.get("Meta")
            if hasattr(Meta, "abstract") and getattr(Meta, "abstract"):
                # if the class is abstract, don't create permissions for it, just return the class object            
                return super(MyModelMeta, cls).__new__(cls, name, bases, attrs)

        if not Meta:
            # create a new Meta Class
            Meta = type('Meta', (object,), {})

        setattr(Meta, 'permissions',(("read_%s"%name.lower(), "Can read %s"%name.lower()),))
        attrs['Meta'] = Meta
        return super(MyModelMeta, cls).__new__(cls, name, bases, attrs)        

create an abstract django models and set the meta class memeber to MyModelMeta:

class MyAbstractModel(models.Model):
    __metaclass__ = MyModelMeta

    class Meta:
        abstract=True

now, create a normal django model like so:

class SomeModel(MyAbstractModel):
    someFieldName = models.CharField(max_length=256, db_index=True)

this will generate the default add/change/delete_somemodel permissions, but also it will add a new read_somemodel permission.

if you're also using south, use this to generate the extra permissions:

from django.db.models import get_app, get_models
from django.contrib.auth.management import create_permissions

create_permissions(get_app(app), get_models(), 2 if settings.DEBUG else 0)

Answer 5

I write test for your issue. I use django 1.2.1 and i have great result!

If you want to add permission to your existing model from inherit model, every time when you change them you need to run "syncdb". Example 100% works.(in 1.2.1 without patch)

It now works.

alt text http://img203.imageshack.us/img203/7500/permn.png

Example:

from django.db import models
from django.contrib import admin

class permissions(models.Model):
    class Meta:
        abstract = True
        permissions = (("test_permission","test permission"),)


class SomeClass(permissions):
    name = models.CharField(max_length=255,verbose_name="Name")

admin.site.register(SomeClass)

Answer 6

In my case explicitly inheriting the Meta didn't work because of South. See this ticket.

django-admin.py syncdb --all fixed the problem.