Moved permission checking logic to model, simplyfing it and adding group support too

apps/permissions/models.py

@@ -2,6 +2,7 @@ from django.db import models
 from django.utils.translation import ugettext_lazy as _
 from django.contrib.contenttypes.models import ContentType
 from django.contrib.contenttypes import generic
+from django.contrib.auth.models import User, Group
 
 
 class PermissionManager(models.Manager):
@@ -25,7 +26,34 @@ class Permission(models.Model):
 
     def __unicode__(self):
         return self.label
+        
+    def get_holders(self):
+        return [holder.holder_object for holder in self.permissionholder_set.all()]
+        
+    def has_permission(self, requester):
+        if isinstance(requester, User):
+            if requester.is_superuser or requester.is_staff:
+                return True
 
+        # Request is one of the permission's holders?
+        if requester in self.get_holders():
+            return True
+        
+        # If not check if the requesters memberships objects is one of 
+        # the permission's holder?
+        roles = RoleMember.objects.get_roles_for_member(requester)
+
+        if isinstance(requester, User):
+            groups = requester.groups.all()
+        else:
+            groups = []
+            
+        result = False
+        for membership in list(set(roles) | set(groups)):
+            result |= self.has_permission(membership)
+
+        return result
+        
 
 class PermissionHolder(models.Model):
     permission = models.ForeignKey(Permission, verbose_name=_(u'permission'))
@@ -40,7 +68,7 @@ class PermissionHolder(models.Model):
         verbose_name_plural = _(u'permission holders')
 
     def __unicode__(self):
-        return unicode(self.holder_object)
+        return u'%s: %s' % (self.holder_type, self.holder_object)
 
 
 class Role(models.Model):
@@ -66,6 +94,12 @@ class Role(models.Model):
         return ('role_list',)
 
 
+class RoleMemberManager(models.Manager):
+    def get_roles_for_member(self, member_obj):
+        member_type = ContentType.objects.get_for_model(member_obj)
+        return [role_member.role for role_member in RoleMember.objects.filter(member_type=member_type, member_id=member_obj.pk)]
+
+
 class RoleMember(models.Model):
     role = models.ForeignKey(Role, verbose_name=_(u'role'))
     member_type = models.ForeignKey(ContentType,
@@ -74,6 +108,8 @@ class RoleMember(models.Model):
     member_id = models.PositiveIntegerField()
     member_object = generic.GenericForeignKey(ct_field='member_type', fk_field='member_id')
 
+    objects = RoleMemberManager()
+
     class Meta:
         #ordering = ('label',)
         verbose_name = _(u'role member')