add support for additional groups

gnuviechadmin/osusers/models.py

@@ -1,4 +1,6 @@
 from django.db import models
+from django.core.exceptions import ValidationError
+from django.utils.translation import ugettext as _
 
 from model_utils.models import TimeStampedModel
 
@@ -29,3 +31,16 @@ class Shadow(TimeStampedModel, models.Model):
     inactdays = models.PositiveSmallIntegerField(blank=True, null=True)
     expiredays = models.PositiveSmallIntegerField(blank=True, null=True,
                                                   default=None)
+
+
+class AdditionalGroup(TimeStampedModel, models.Model):
+    user = models.ForeignKey(User)
+    group = models.ForeignKey(Group)
+
+    class Meta:
+        unique_together = ('user', 'group')
+
+    def clean(self):
+        if self.user.group == self.group:
+            raise ValidationError(_(
+                "You can not use a user's primary group."))