Django ManyToMany relationship with abstract base - not possible, but is there a better way?

Given the following models:

class BaseMachine(models.Model)
    fqdn = models.CharField(max_length=150)
    cpus = models.IntegerField()
    memory = models.IntegerField()

    class Meta:
        abstract = True

class PhysicalMachine(BaseMachine)
    location = models.CharField(max_length=150)


class VirtualMachine(BaseMachine)
    hypervisor = models.CharField(max_length=5)


class Sysadmin(models.Model):
    name = models.CharField(max_length=100)
    admin_of = models.ManyToManyField...

In this example I would like to relate 1 sysadmin to many machines - be them either an instance or PhysicalMachine or VirtualMachine. I know I can't have a ManyToMany with an abstract base, but I was wondering if there was a better way of achieving this than just having a separate ManyToMany field on sysadmin for each of the models? In this small examp开发者_Python百科le that could be tolerable, but if you have more than 2 subclasses, or if there are other models which you need to relate with the 'base' class, it becomes something more to manage.

Thanks :)

EDIT: I have updated the soultion, so one admin can have many machines and one machine can have many admins:

class Sysadmin(models.Model):
    name = models.CharField(max_length=100)


class BaseMachine(models.Model):
    fqdn = models.CharField(max_length=150)
    cpus = models.IntegerField()
    memory = models.IntegerField()
    admins = models.ManyToManyField(Sysadmin)

    class Meta:
        abstract = True

class PhysicalMachine(BaseMachine):
    location = models.CharField(max_length=150)


class VirtualMachine(BaseMachine):
    hypervisor = models.CharField(max_length=5)



In [1]: s1 = Sysadmin(name='mike')

In [2]: s1.save()

In [3]: m1 = PhysicalMachine(fqdn='test', cpus=1, memory=20, location='test')

In [4]: m1.save()

In [5]: m1.admins.add(s1)

In [6]: m1.save()

In [7]: m2 = VirtualMachine(fqdn='test', cpus=1, memory=20, hypervisor='test')

In [8]: m2.save()

In [9]: m2.admins.add(s1)

In [10]: m2.save()

In [11]: m1.admins.all()
Out[11]: [<Sysadmin: Sysadmin object>]

In [12]: m2.admins.all()
Out[12]: [<Sysadmin: Sysadmin object>]

Have you considered a generic relationship using the contenttypes framework?