Refactor with new funcions: group.is_chair(user) and group.get_chair()

See #904
 - Legacy-Id: 5070

ietf/group/models.py

@@ -36,7 +36,7 @@ class Group(GroupInfo):
 
     acronym = models.SlugField(max_length=40, unique=True, db_index=True)
     charter = models.OneToOneField('doc.Document', related_name='chartered_group', blank=True, null=True)
-    
+
     def latest_event(self, *args, **filter_args):
         """Get latest event of optional Python type and with filter
         arguments, e.g. g.latest_event(type="xyz") returns a GroupEvent
@@ -46,6 +46,17 @@ class Group(GroupInfo):
         e = model.objects.filter(group=self).filter(**filter_args).order_by('-time', '-id')[:1]
         return e[0] if e else None
 
+    def is_chair(self, user):
+        chair = self.get_chair()
+        if chair:
+            return self.get_chair().person.user == user
+        else:
+            return False
+
+    def get_chair(self):
+        chair = self.role_set.filter(name__slug='chair')[:1]
+        return chair and chair[0] or None
+
 class GroupHistory(GroupInfo):
     group = models.ForeignKey(Group, related_name='history_set')
     acronym = models.CharField(max_length=40)

ietf/nomcom/forms.py

@@ -30,7 +30,7 @@ class EditMembersFormPreview(FormPreview):
         group = get_object_or_404(NomComGroup,
                                   acronym__icontains=year,
                                   state__slug='active')
-        is_group_chair = bool(group.role_set.filter(person__user=request.user, name__slug='chair')[:1])
+        is_group_chair = group.is_chair(request.user)
         is_secretariat = has_role(request.user, "Secretariat")
         if not is_secretariat and not is_group_chair:
             return HttpResponseForbidden("Must be a secretariat or group chair")
@@ -110,9 +110,9 @@ class EditChairFormPreview(FormPreview):
         return super(EditChairFormPreview, self).__call__(request, *args, **kwargs)
 
     def parse_params(self, *args, **kwargs):
-        chairs = self.group.role_set.filter(name__slug='chair')
-        if chairs:
-            self.form.base_fields['chair'].initial = chairs[0].email.address
+        chair = self.group.get_chair()
+        if chair:
+            self.form.base_fields['chair'].initial = chair.email.address
 
     def process_preview(self, request, form, context):
         chair_email = form.cleaned_data['chair']