#273 Alphanumeric ordering

catalog/expressions.py

@@ -0,0 +1,8 @@
+from django.db.models import Func
+
+
+class Substring(Func):
+    function = 'substring'
+    arity = 2
+
+

catalog/models.py

@@ -13,6 +13,8 @@
 from django.utils.translation import ugettext_lazy as _
 from unidecode import unidecode
 
+from catalog.expressions import Substring
+
 SLUG_MAX_LENGTH = 50
 
 
@@ -225,27 +227,30 @@ def __str__(self):
 
 
 class TagQuerySet(models.QuerySet):
+    # @todo #273:30m Apply new order_by_alphanumeric for SE/STB.
+
+    # @todo #273:60m Create an index for order_by_alphanumeric query.
+    def order_by_alphanumeric(self):
+        """Sort the Tag by name's alphabetic chars and then by numeric chars."""
+        return self.annotate(
+            tag_name=Substring(models.F('name'), models.Value('[a-zA-Zа-яА-Я]+')),
+            tag_value=models.functions.Cast(
+                Substring(models.F('name'), models.Value('[0-9]+\.?[0-9]*')),
+                models.FloatField(),
+        )).order_by('tag_name', 'tag_value')
 
     def filter_by_products(self, products: Iterable[AbstractProduct]):
-        ordering = settings.TAGS_ORDER
-        distinct = [order.lstrip('-') for order in ordering]
-
         return (
             self
             .filter(products__in=products)
-            .order_by(*ordering)
-            .distinct(*distinct, 'id')
+            .distinct()
         )
 
     def exclude_by_products(self, products: Iterable[AbstractProduct]):
-        ordering = settings.TAGS_ORDER
-        distinct = [order.lstrip('-') for order in ordering]
-
         return (
             self
             .exclude(products__in=products)
-            .order_by(*ordering)
-            .distinct(*distinct, 'id')
+            .distinct()
         )
 
     def get_group_tags_pairs(self) -> List[Tuple[TagGroup, List['Tag']]]:
@@ -378,11 +383,8 @@ def parsed(self, raw: str):
 
 class TagManager(models.Manager.from_queryset(TagQuerySet)):
 
-    def get_queryset(self):
-        return (
-            super().get_queryset()
-            .order_by(*settings.TAGS_ORDER)
-        )
+    def order_by_alphanumeric(self):
+        return self.get_queryset().order_by_alphanumeric()
 
     def get_group_tags_pairs(self):
         return self.get_queryset().get_group_tags_pairs()

tests/catalog/test_models.py

@@ -1,5 +1,6 @@
 """Defines tests for models in Catalog app."""
 import unittest
+from random import shuffle
 
 from django.db import DataError
 from django.test import TestCase
@@ -289,3 +290,17 @@ def test_long_name(self):
             self.assertLessEqual(len(tag.slug), catalog.models.SLUG_MAX_LENGTH)
         except DataError as e:
             self.assertTrue(False, f'Tag has too long name. {e}')
+
+    def test_order_by_alphanumeric(self):
+        ordered_tags = [
+            catalog_models.MockTag(name=name)
+            for name in [
+                'a', 'b', '1 A', '2.1 A', '1.2 В', '1.2 В', '1.6 В', '5 В', '12 В',
+            ]
+        ]
+
+        # reverse just in case
+        catalog_models.MockTag.objects.bulk_create(shuffle(ordered_tags))
+
+        for i, tag in enumerate(catalog_models.MockTag.objects.order_by_alphanumeric()):
+            self.assertEqual(tag, ordered_tags[i])

tests/test_settings.py

@@ -124,8 +124,6 @@
 TAGS_TITLE_DELIMITER = ' или '
 TAG_GROUPS_TITLE_DELIMITER = ' и '
 
-TAGS_ORDER = ['group__position', 'group__name', 'position', 'name']
-
 # random string to append to doubled slugs
 SLUG_HASH_SIZE = 5