Query exclude via model_set property?

[Joshua Russo]

I have a 3 table solution

class Organization(models.Model):

    name = models.CharField("Organization's name", max_length=100)

class OrganizationDepartment(models.Model):

    organization = models.ForeignKey(Organization)

    name         = models.CharField("Name", max_length=100)

    contacts     = models.ManyToManyField("Contact")

class Contact(models.Model):

    organization = models.ForeignKey("Organization", blank=True, null=True)

    name         = models.CharField("Contact's name", max_length=100)

I want to create a list of contacts within an organization and not in a given department. The problem is that it looks like I can't use the contact.organzationdepartment_set in an exclude. Is that correct?

[Joshua Russo]

it looks like this is the best way to tackle the problem. 

http://stackoverflow.com/questions/1724317/django-exclude-on-a-many-to-many-relationship-through-a-third-table