Optimises queries through simplifying repeated queries and select_related use

registrasion/controllers/cart.py

@@ -80,6 +80,11 @@ class CartController(object):
         pairs. '''
 
         items_in_cart = rego.ProductItem.objects.filter(cart=self.cart)
+        items_in_cart = items_in_cart.select_related(
+            "product",
+            "product__category",
+        )
+
         product_quantities = list(product_quantities)
 
         # n.b need to add have the existing items first so that the new
@@ -283,6 +288,7 @@ class CartController(object):
 
         # Fix products and discounts
         items = rego.ProductItem.objects.filter(cart=self.cart)
+        items = items.select_related("product")
         products = set(i.product for i in items)
         available = set(ProductController.available_products(
             self.cart.user,
@@ -302,7 +308,9 @@ class CartController(object):
         # Delete the existing entries.
         rego.DiscountItem.objects.filter(cart=self.cart).delete()
 
-        product_items = self.cart.productitem_set.all()
+        product_items = self.cart.productitem_set.all().select_related(
+            "product", "product__category",
+        )
 
         products = [i.product for i in product_items]
         discounts = discount.available_discounts(self.cart.user, [], products)
@@ -310,6 +318,7 @@ class CartController(object):
         # The highest-value discounts will apply to the highest-value
         # products first.
         product_items = self.cart.productitem_set.all()
+        product_items = product_items.select_related("product")
         product_items = product_items.order_by('product__price')
         product_items = reversed(product_items)
         for item in product_items:

registrasion/controllers/category.py

@@ -22,7 +22,7 @@ class CategoryController(object):
         from product import ProductController
 
         if products is AllProducts:
-            products = rego.Product.objects.all()
+            products = rego.Product.objects.all().select_related("category")
 
         available = ProductController.available_products(
             user,

registrasion/controllers/conditions.py

@@ -1,4 +1,5 @@
 import itertools
+import operator
 
 from collections import defaultdict
 from collections import namedtuple
@@ -90,12 +91,22 @@ class ConditionController(object):
             quantities = {}
 
         # Get the conditions covered by the products themselves
-        all_conditions = [
+
-            product.enablingconditionbase_set.select_subclasses() |
+        prods = (
-            product.category.enablingconditionbase_set.select_subclasses()
+            product.enablingconditionbase_set.select_subclasses()
             for product in products
-        ]
+        )
-        all_conditions = set(itertools.chain(*all_conditions))
+        # Get the conditions covered by their categories
+        cats = (
+            category.enablingconditionbase_set.select_subclasses()
+            for category in set(product.category for product in products)
+        )
+
+        if products:
+            # Simplify the query.
+            all_conditions = reduce(operator.or_, itertools.chain(prods, cats))
+        else:
+            all_conditions = []
 
         # All mandatory conditions on a product need to be met
         mandatory = defaultdict(lambda: True)
@@ -115,10 +126,14 @@ class ConditionController(object):
             from_category = rego.Product.objects.filter(
                 category__in=condition.categories.all(),
             ).all()
-            all_products = set(itertools.chain(cond_products, from_category))
+            all_products = cond_products | from_category
-
+            all_products = all_products.select_related("category")
             # Remove the products that we aren't asking about
-            all_products = all_products & products
+            all_products = [
+                product
+                for product in all_products
+                if product in products
+            ]
 
             if quantities:
                 consumed = sum(quantities[i] for i in all_products)

registrasion/controllers/discount.py

@@ -13,7 +13,7 @@ class DiscountAndQuantity(object):
         self.quantity = quantity
 
     def __repr__(self):
-        print "(discount=%s, clause=%s, quantity=%d)" % (
+        return "(discount=%s, clause=%s, quantity=%d)" % (
             self.discount, self.clause, self.quantity,
         )
 
@@ -37,11 +37,20 @@ def available_discounts(user, categories, products):
     )
     # (Not relevant: discounts that match products in provided categories)
 
+    product_discounts = product_discounts.select_related(
+        "product",
+        "product__category",
+    )
+
+    all_category_discounts = category_discounts | product_category_discounts
+    all_category_discounts = all_category_discounts.select_related(
+        "category",
+    )
+
     # The set of all potential discounts
     potential_discounts = set(itertools.chain(
         product_discounts,
-        category_discounts,
+        all_category_discounts,
-        product_category_discounts,
     ))
 
     discounts = []
@@ -50,6 +59,7 @@ def available_discounts(user, categories, products):
     accepted_discounts = set()
     failed_discounts = set()
 
+
     for discount in potential_discounts:
         real_discount = rego.DiscountBase.objects.get_subclass(
             pk=discount.discount.pk,
@@ -63,7 +73,7 @@ def available_discounts(user, categories, products):
             cart__user=user,
             cart__active=False,  # Only past carts count
             cart__released=False,  # You can reuse refunded discounts
-            discount=discount.discount,
+            discount=real_discount,
         )
         agg = past_uses.aggregate(Sum("quantity"))
         past_use_count = agg["quantity__sum"]

registrasion/controllers/product.py

@@ -23,18 +23,25 @@ class ProductController(object):
 
         if category is not None:
             all_products = rego.Product.objects.filter(category=category)
+            all_products = all_products.select_related("category")
         else:
             all_products = []
 
         if products is not None:
-            all_products = itertools.chain(all_products, products)
+            all_products = set(itertools.chain(all_products, products))
+
+        cat_quants = dict(
+            (
+                category,
+                CategoryController(category).user_quantity_remaining(user),
+            )
+            for category in set(product.category for product in all_products)
+        )
 
         passed_limits = set(
             product
             for product in all_products
-            if CategoryController(product.category).user_quantity_remaining(
+            if cat_quants[product.category] > 0
-                user
-            ) > 0
             if cls(product).user_quantity_remaining(user) > 0
         )
 

registrasion/templatetags/registrasion_tags.py

@@ -30,7 +30,7 @@ def items_pending(context):
     all_items = rego.ProductItem.objects.filter(
         cart__user=context.request.user,
         cart__active=True,
-    )
+    ).select_related("product", "product__category")
     return all_items
 
 
@@ -42,17 +42,18 @@ def items_purchased(context, category=None):
     all_items = rego.ProductItem.objects.filter(
         cart__user=context.request.user,
         cart__active=False,
-    )
+        cart__released=False,
+    ).select_related("product", "product__category")
 
     if category:
         all_items = all_items.filter(product__category=category)
 
-    products = set(item.product for item in all_items)
+    pq = all_items.values("product").annotate(quantity=Sum("quantity")).all()
+    products = rego.Product.objects.all()
     out = []
-    for product in products:
+    for item in pq:
-        pp = all_items.filter(product=product)
+        prod = products.get(pk=item["product"])
-        quantity = pp.aggregate(Sum("quantity"))["quantity__sum"]
+        out.append(ProductAndQuantity(prod, item["quantity"]))
-        out.append(ProductAndQuantity(product, quantity))
     return out
 
 

registrasion/views.py

@@ -115,11 +115,20 @@ def guided_registration(request, page_id=0):
             current_step = 3
             title = "Additional items"
 
-        for category in cats:
+        all_products = rego.Product.objects.filter(
-            products = ProductController.available_products(
+            category__in=cats,
+        ).select_related("category")
+
+        available_products = set(ProductController.available_products(
             request.user,
-                category=category,
+            products=all_products,
-            )
+        ))
+
+        for category in cats:
+            products = [
+                i for i in available_products
+                if i.category == category
+            ]
 
             prefix = "category_" + str(category.id)
             p = handle_products(request, category, products, prefix)
@@ -280,15 +289,17 @@ def handle_products(request, category, products, prefix):
     items = rego.ProductItem.objects.filter(
         product__in=products,
         cart=current_cart.cart,
-    )
+    ).select_related("product")
     quantities = []
-    for product in products:
+    seen = set()
-        # Only add items that are enabled.
+
-        try:
+    for item in items:
-            quantity = items.get(product=product).quantity
+        quantities.append((item.product, item.quantity))
-        except ObjectDoesNotExist:
+        seen.add(item.product)
-            quantity = 0
+
-        quantities.append((product, quantity))
+    zeros = set(products) - seen
+    for product in zeros:
+        quantities.append((product, 0))
 
     products_form = ProductsForm(
         request.POST or None,
@@ -323,8 +334,12 @@ def handle_products(request, category, products, prefix):
 def set_quantities_from_products_form(products_form, current_cart):
 
     quantities = list(products_form.product_quantities())
+
+    pks = [i[0] for i in quantities]
+    products = rego.Product.objects.filter(id__in=pks).select_related("category")
+
     product_quantities = [
-        (rego.Product.objects.get(pk=i[0]), i[1]) for i in quantities
+        (products.get(pk=i[0]), i[1]) for i in quantities
     ]
     field_names = dict(
         (i[0][0], i[1][2]) for i in zip(product_quantities, quantities)