Change your model Structure to This:
class Driver(models.Model):
name = models.CharField(max_length=200)
executable = models.CharField(max_length=200)
class Device(models.Model):
name = models.CharField(max_length=200)
bound_driver = models.ForeignKey(Driver, related_name="bound_to")
available_drivers = models.ManyToManyfield(Driver)
ManyToManyField would do the same work as DriverAssignment Table.
You can add Available drivers in Available drivers field.
But then You would also Want that bound_driver is one of the Available Drivers. This validation you will have to do in forms. For that you have to over-ride Admin forms. See links
Links of Reference:
ManytoMany field: https://docs.djangoproject.com/en/1.6/ref/models/fields/#django.db.models.ManyToManyField
Model Admin (to over-ride admin functionality): https://docs.djangoproject.com/en/1.6/ref/contrib/admin/#modeladmin-objects
You will have to spend some time reading and implementing if you want ot learn more. :)
OR
If you want to go with the same structure, than you will have to over-ride the form
in ModelAdmin
see here and Provide you custom form, which will be something like this:
class CustomForm(ModelForm)
bound_driver = forms.ModelChoiceField(queryset = <your custom queryset that returns only available drivers>, ...)
class Meta:
model = Device
https://docs.djangoproject.com/en/1.6/ref/contrib/admin/#django.contrib.admin.ModelAdmin.form