#611,697,710 Section and Category min_price, optimize Category.get_se…

…ries (#716)

* #697  Implement min price for high level categories

* #710  Clarify Category.min_price arch

* #710  Implement Section.get_min_price

* #611  Optimize get_series queries

stroyprombeton/models.py

@@ -76,29 +76,19 @@ def get_series(self) -> models.QuerySet:
                     .select_related('product')
                     .select_related('product__category')
                     .filter(
-                        product__category__in=(
-                            # @todo #597:30m  Check mptt's `get_descendants` default optimization.
-                            #  Check if the method already contains
-                            #  relevant prefetch/select_related for parent, children fields.
-                            Category.objects
-                            .select_related('parent')
-                            .prefetch_related('children')
-                            .filter(id=self.id)
-                            .get_descendants(include_self=True)
-                            .active()
-                        )
+                        product__in=Product.objects.filter_descendants(self)
                     ).values('id')
                 )
             ).distinct()
             .order_by('name')
         )
 
+    def recursive_products(self) -> 'ProductQuerySet':
+        return Product.objects.filter_descendants(self)
+
     def get_min_price(self) -> float:
-        return (
-            Option.objects
-            .filter(product__in=self.products.active())
-            .min_price()
-        )
+        """Helper for templates."""
+        return self.recursive_products().options().min_price()
 
 
 class SeriesQuerySet(models.QuerySet):
@@ -180,7 +170,8 @@ def _get_slug(self) -> str:
         )
 
     def get_min_price(self) -> float:
-        return Option.objects.filter(series=self).min_price()
+        """Helper for templates."""
+        return self.options.min_price()
 
     def save(self, *args, **kwargs):
         if not self.slug:
@@ -249,14 +240,9 @@ def get_absolute_url(self):
         """Url path to the related page."""
         return reverse('section', args=(self.page.slug,))
 
-    # @todo #669:60m  Implement `Section.get_min_price` method.
-    #  And look at the get_min_price arch in a whole.
-    #  Maybe only ProductsQS and OptionsQS should have min_price,
-    #  but Section and Series should not.
-    #  Category, Series and Product page templates at the production DB
-    #  contains series min price usage.
     def get_min_price(self) -> float:
-        raise NotImplemented()
+        """Helper for templates."""
+        return self.products.options().min_price()
 
 
 class OptionQuerySet(models.QuerySet):
@@ -268,6 +254,7 @@ def bind_fields(self):
         """Prefetch or select typical related fields to reduce sql queries count."""
         return (
             self.select_related('product')
+            .select_related('series')
             .prefetch_related('tags')
         )
 
@@ -382,11 +369,27 @@ class ProductQuerySet(catalog.models.ProductQuerySet):
     def get_series(self):
         pass
 
+    def options(self) -> OptionQuerySet:
+        return Option.objects.filter(product__in=self).distinct()
+
+
+class ProductManager(models.Manager.from_queryset(ProductQuerySet)):
+    """Get all products of given category by Category's id or instance."""
+
+    def filter_descendants(self, category: Category) -> ProductQuerySet:
+        return self.get_queryset().filter_descendants(category)
+
+    def active(self):
+        return self.get_queryset().active()
+
+    def tagged(self, tags: typing.Iterable['Tag']):
+        return self.get_queryset().tagged(tags)
+
 
 # not inherited from `catalog.models.AbstractProduct`, because
 # AbstractProduct's set of fields is shared between Product and Option models.
 class Product(catalog.models.AbstractProduct, pages.models.PageMixin):
-    objects = catalog.models.ProductManager()
+    objects = ProductManager()
 
     name = models.CharField(max_length=255, db_index=True, verbose_name=_('name'))
     category = models.ForeignKey(

stroyprombeton/tests/tests_models.py

@@ -1,5 +1,3 @@
-import unittest
-
 from django.test import TestCase, tag
 
 from pages import models as pages_models
@@ -15,19 +13,33 @@ def test_series(self):
         option = stb_models.Option.objects.first()
         least = option.product.category
         root = least.get_root()
+        self.assertNumQueries(2, lambda: len(root.get_series()))
         self.assertIn(option.series, least.get_series())
         self.assertIn(option.series, root.get_series())
 
-    # @todo #692:30m  Implement min_price for non-leaf category.
-    @unittest.expectedFailure
     def test_min_price(self):
         """Non-leaf category should find min price recursively."""
         option = stb_models.Option.objects.filter(price__gt=0).first()
         category = option.product.category.parent
+        self.assertNumQueries(1, category.get_min_price)
         self.assertGreater(category.get_min_price(), 0)
         self.assertLessEqual(category.get_min_price(), option.price)
 
 
+@tag('fast')
+class Section(TestCase):
+
+    fixtures = ['dump.json']
+
+    def test_min_price(self):
+        """Non-leaf category should find min price recursively."""
+        option = stb_models.Option.objects.filter(price__gt=0).first()
+        section = option.product.section
+        self.assertNumQueries(1, section.get_min_price)
+        self.assertGreater(section.get_min_price(), 0)
+        self.assertLessEqual(section.get_min_price(), option.price)
+
+
 @tag('fast')
 class Option_(TestCase):