add product

apps/shop/ordering.py

@@ -0,0 +1,18 @@
+from django.db.models import F
+from django.db.models.functions import Coalesce
+
+
+def category_ordering(prefix='', excel=False):
+    field = F(prefix + 'order_cat')
+    if excel:
+        field = Coalesce(prefix + 'excel_order', prefix + 'order_cat')
+    return (field.asc(nulls_last=True), prefix + 'name', prefix + 'pk')
+
+
+def product_ordering(prefix='', excel=False):
+    field = F(prefix + 'order_prd')
+    if excel:
+        field = Coalesce(prefix + 'excel_order', prefix + 'order_prd')
+    return category_ordering(prefix + 'category__', excel) + (
+        field.asc(nulls_last=True), prefix + 'name', prefix + 'pk',
+    )