Add custom Manager for Account model.

- When Account model is queried with Account.objects, it always add
  .select_related('cofprofile_user', 'negative').
- Eg benefits: history doesn't do anymore one request by account to
  fill the account filter.

Important

Using this workaround (systemically append select_related) can be
dangerous normally, however a certain number of properties in
cofprofile and user are frequently used (as firstname or lastname), and
the benefits seems greater.

kfet/backends.py

@@ -46,6 +46,10 @@ class GenericTeamBackend(object):
 
     def get_user(self, user_id):
         try:
-            return User.objects.get(pk=user_id)
+            return (
+                User.objects
+                .select_related('profile__acount_kfet')
+                .get(pk=user_id)
+            )
         except User.DoesNotExist:
             return None

kfet/models.py

@@ -27,8 +27,19 @@ def default_promo():
     now = date.today()
     return now.month <= 8 and now.year-1 or now.year
 
-@python_2_unicode_compatible
+
+class AccountManager(models.Manager):
+    """Manager for Account Model."""
+
+    def get_queryset(self):
+        """Always append related data to this Account."""
+        return super().get_queryset().select_related('cofprofile__user',
+                                                     'negative')
+
+
 class Account(models.Model):
+    objects = AccountManager()
+
     cofprofile = models.OneToOneField(
         CofProfile, on_delete = models.PROTECT,
         related_name = "account_kfet")

kfet/views.py

@@ -346,35 +346,32 @@ def account_create_ajax(request, username=None, login_clipper=None,
             'user_form'    : forms['user_form'],
             })
 
+
 # Account - Read
 
 @login_required
 def account_read(request, trigramme):
-    try:
+    account = get_object_or_404(Account, trigramme=trigramme)
-        account = (
-            Account.objects
-            .select_related('cofprofile__user', 'negative')
-            .get(trigramme=trigramme)
-        )
-    except Account.DoesNotExist:
-        raise Http404
 
     # Checking permissions
     if not request.user.has_perm('kfet.is_team') \
             and request.user != account.user:
         raise PermissionDenied
 
-    addcosts = (OperationGroup.objects
+    addcosts = (
-            .filter(opes__addcost_for=account,opes__canceled_at=None)
+        OperationGroup.objects
-            .extra({'date':"date(at)"})
+        .filter(opes__addcost_for=account,
-            .values('date')
+                opes__canceled_at=None)
-            .annotate(sum_addcosts=Sum('opes__addcost_amount'))
+        .extra({'date': "date(at)"})
-            .order_by('-date'))
+        .values('date')
+        .annotate(sum_addcosts=Sum('opes__addcost_amount'))
+        .order_by('-date')
+    )
 
     return render(request, "kfet/account_read.html", {
-        'account' : account,
+        'account': account,
         'addcosts': addcosts,
-        'settings': { 'subvention_cof': Settings.SUBVENTION_COF() },
+        'settings': {'subvention_cof': Settings.SUBVENTION_COF()},
     })
 
 # Account - Update