Refactor price with database queries and start reports

src/checkout/settings.py

@@ -86,6 +86,7 @@ INSTALLED_APPS = [
     "purchase",
     "crispy_forms",
     "crispy_bootstrap5",
+    "django_extensions",
 ]
 
 MIDDLEWARE = [

src/common/templates/common/navbar.html

@@ -15,6 +15,9 @@
                     <li class="nav-item">
                         <a href="{% url "purchase:list" %}" class="nav-link">Baskets</a>
                     </li>
+                    <li class="nav-item">
+                        <a href="{% url "purchase:reports" %}" class="nav-link">Reports</a>
+                    </li>
                 {% endif %}
                 {% if user.is_staff %}
                     <li class="nav-item">

src/purchase/admin.py

@@ -2,6 +2,7 @@ from django.contrib import admin
 from django.contrib.admin import register
 
 from purchase.models import Basket, BasketItem, PaymentMethod, Product
+from purchase.templatetags.purchase import currency
 
 
 @register(Product)
@@ -10,14 +11,17 @@ class ProductAdmin(admin.ModelAdmin):
     list_editable = ["display_order"]
     search_fields = ["name"]
 
+    def get_queryset(self, request):
+        return super().get_queryset(request).with_sold().with_turnover()
+
     def unit_price(self, instance: Product):
-        return instance.unit_price_display
+        return currency(instance.unit_price_cents)
 
     def sold(self, instance: Product):
         return instance.sold
 
     def turnover(self, instance: Product):
-        return instance.turnover_display
+        return currency(instance.turnover)
 
 
 @register(PaymentMethod)
@@ -25,8 +29,11 @@ class PaymentMethodAdmin(admin.ModelAdmin):
     list_display = ["name", "turnover"]
     search_fields = ["name"]
 
+    def get_queryset(self, request):
+        return super().get_queryset(request).with_turnover()
+
     def turnover(self, instance: Product):
-        return instance.turnover_display
+        return currency(instance.turnover)
 
 
 class BasketItemInline(admin.TabularInline):
@@ -35,18 +42,24 @@ class BasketItemInline(admin.TabularInline):
     extra = 0
     readonly_fields = ["price"]
 
+    def get_queryset(self, request):
+        return super().get_queryset(request).priced()
+
     def price(self, instance) -> str:
-        return instance.price_display
+        return currency(instance.price)
 
 
 @register(Basket)
 class BasketAdmin(admin.ModelAdmin):
     list_display = ["id", "payment_method", "created_at", "price"]
-    fields = ["created_at", "payment_method"]
+    fields = ["created_at", "payment_method", "price"]
     list_filter = ["payment_method"]
     date_hierarchy = "created_at"
-    readonly_fields = ["created_at"]
+    readonly_fields = ["created_at", "price"]
     inlines = [BasketItemInline]
 
+    def get_queryset(self, request):
+        return super().get_queryset(request).priced()
+
     def price(self, instance) -> str:
-        return instance.price_display
+        return currency(instance.price)

src/purchase/layout.py

@@ -2,7 +2,7 @@ from crispy_forms.layout import Field
 
 
 class BasketItemField(Field):
-    template = "purchase/basket_item.html"
+    template = "purchase/snippets/basket_item.html"
 
     def __init__(self, *args, product, **kwargs):
         super().__init__(*args, **kwargs)

src/purchase/models.py

@@ -1,4 +1,5 @@
 from django.db import models
+from django.db.models import Count, F, Sum
 from django.urls import reverse
 from PIL import Image, ImageOps
 
@@ -11,53 +12,53 @@ class Model(models.Model):
         abstract = True
 
 
+class PaymentMethodQuerySet(models.QuerySet):
+    def with_turnover(self):
+        return self.annotate(
+            turnover=Sum(
+                F("baskets__items__quantity")
+                * F("baskets__items__product__unit_price_cents")
+            )
+        )
+
+
 class PaymentMethod(Model):
     name = models.CharField(max_length=50, unique=True)
 
+    objects = PaymentMethodQuerySet.as_manager()
+
     def __str__(self):
         return self.name
 
-    @property
-    def turnover(self) -> int:
-        return sum(basket.price for basket in self.baskets.all())
-
-    @property
-    def turnover_display(self) -> str:
-        return f"{self.turnover / 100}€"
-
 
 def default_product_display_order():
     return Product.objects.last().display_order + 1
 
 
+class ProductQuerySet(models.QuerySet):
+    def with_turnover(self):
+        return self.annotate(
+            turnover=Sum(F("basket_items__quantity") * F("unit_price_cents"))
+        )
+
+    def with_sold(self):
+        return self.annotate(sold=Sum("basket_items__quantity"))
+
+
 class Product(Model):
     name = models.CharField(max_length=250, unique=True)
     image = models.ImageField(null=True, blank=True)
     unit_price_cents = models.PositiveIntegerField()
     display_order = models.PositiveIntegerField(default=default_product_display_order)
 
+    objects = ProductQuerySet.as_manager()
+
     class Meta:
         ordering = ["display_order", "name"]
 
     def __str__(self):
         return self.name
 
-    @property
-    def unit_price_display(self) -> str:
-        return f"{self.unit_price_cents / 100}€"
-
-    @property
-    def turnover(self) -> int:
-        return sum(items.price for items in self.basket_items.all())
-
-    @property
-    def turnover_display(self) -> str:
-        return f"{self.turnover / 100}€"
-
-    @property
-    def sold(self):
-        return sum(items.quantity for items in self.basket_items.all())
-
     def save(self, *args, **kwargs):
         super().save()
         with Image.open(self.image.path) as img:
@@ -92,6 +93,13 @@ class Product(Model):
             img.save(self.image.path)
 
 
+class BasketQuerySet(models.QuerySet):
+    def priced(self):
+        return self.annotate(
+            price=Sum(F("items__quantity") * F("items__product__unit_price_cents"))
+        )
+
+
 class Basket(Model):
     payment_method = models.ForeignKey(
         to=PaymentMethod,
@@ -101,22 +109,20 @@ class Basket(Model):
         blank=True,
     )
 
+    objects = BasketQuerySet.as_manager()
+
     def __str__(self):
         return f"Panier #{self.id}"
 
-    @property
-    def price(self) -> int:
-        return sum(item.price for item in self.items.all())
-
-    @property
-    def price_display(self) -> str:
-        price = self.price / 100
-        return f"{price}€"
-
     def get_absolute_url(self):
         return reverse("purchase:update", args=(self.pk,))
 
 
+class BasketItemQuerySet(models.QuerySet):
+    def priced(self):
+        return self.annotate(price=F("quantity") * F("product__unit_price_cents"))
+
+
 class BasketItem(Model):
     product = models.ForeignKey(
         to=Product, on_delete=models.PROTECT, related_name="basket_items"
@@ -126,11 +132,4 @@ class BasketItem(Model):
     )
     quantity = models.PositiveIntegerField()
 
-    @property
-    def price(self) -> int:
-        return self.product.unit_price_cents * self.quantity
-
-    @property
-    def price_display(self) -> str:
-        price = self.price / 100
-        return f"{price}€"
+    objects = BasketItemQuerySet.as_manager()

src/purchase/templates/purchase/basket_form.html

@@ -1,5 +1,5 @@
 {% extends "common/base.html" %}
-{% load crispy_forms_tags %}
+{% load crispy_forms_tags purchase %}
 {% block content %}
     {% if object %}
         <h1>{{ object }}</h1>
@@ -9,7 +9,7 @@
     {% crispy form %}
     {% if object %}
         <div>
-            Price: {{ object.price_display }}
+            Price: {{ object.price|currency }}
         </div>
         <a href="{% url "purchase:new" %}" class="btn btn-secondary">New</a>
     {% endif %}

src/purchase/templates/purchase/basket_list.html

@@ -1,4 +1,5 @@
 {% extends "common/base.html" %}
+{% load purchase %}
 {% block content %}
     <h1>Baskets</h1>
     <div class="row row-cols-auto g-4">
@@ -9,7 +10,7 @@
                         <h5 class="card-title">Basket #{{ basket.id }}</h5>
                         <p class="card-text">
                             {{ basket.items.count }} items<br>
-                            {{ basket.price_display }}<br>
+                            {{ basket.price|currency }}<br>
                             {{ basket.payment_method }}
                         </p>
                         {% if perms.purchase.change_basket %}

src/purchase/templates/purchase/reports.html

@@ -0,0 +1,19 @@
+{% extends "common/base.html" %}
+{% load purchase %}
+
+{% block content %}
+    <h1>Reports</h1>
+    <h2>Total turnover</h2>
+    <ul>
+        <li>
+            {{ total|currency }}
+        </li>
+    </ul>
+    <h2>Turnover by day</h2>
+
+    <h2>Products</h2>
+    {% include "purchase/snippets/report_products.html" %}
+    <h2>Turnover by product by day</h2>
+    <h2>Turnover by payment method</h2>
+    <h2>Turnover by payment method by day</h2>
+{% endblock %}

src/purchase/templates/purchase/snippets/report_products.html

@@ -0,0 +1,18 @@
+{% load purchase %}
+
+<table class="table table-hover table-sm">
+    <thead><tr>
+        <th scope="col">Product</th>
+        <th scope="col">Sold</th>
+        <th scope="col">Turnover</th>
+    </tr></thead>
+    <tbody>
+        {% for product in products %}
+            <tr>
+                <th scope="row">{{ product }}</th>
+                <td>{{ product.sold }}</td>
+                <td>{{ product.turnover|currency }}</td>
+            </tr>
+        {% endfor %}
+    </tbody>
+</table>

src/purchase/templatetags/purchase.py

@@ -0,0 +1,10 @@
+from django import template
+
+register = template.Library()
+
+
+@register.filter
+def currency(value):
+    if isinstance(value, int) or isinstance(value, float):
+        return f"{value/100:.2f}€"
+    return value

src/purchase/urls.py

@@ -6,6 +6,7 @@ from purchase.views import (
     NewBasketView,
     UpdateBasketView,
 )
+from purchase.views.reports import ReportsView
 
 app_name = "purchase"
 urlpatterns = [
@@ -13,4 +14,5 @@ urlpatterns = [
     path("new/", NewBasketView.as_view(), name="new"),
     path("<int:pk>/update/", UpdateBasketView.as_view(), name="update"),
     path("<int:pk>/delete/", DeleteBasketView.as_view(), name="delete"),
+    path("reports/", ReportsView.as_view(), name="reports"),
 ]

src/purchase/views/__init__.py

@@ -0,0 +1,3 @@
+from .basket import DeleteBasketView, ListBasketsView, NewBasketView, UpdateBasketView
+
+__all__ = ["NewBasketView", "UpdateBasketView", "DeleteBasketView", "ListBasketsView"]

src/purchase/views/basket.py

@@ -1,14 +1,10 @@
-from django.contrib.auth.mixins import LoginRequiredMixin, PermissionRequiredMixin
 from django.contrib.messages.views import SuccessMessageMixin
 from django.urls import reverse
 from django.views.generic import CreateView, DeleteView, ListView, UpdateView
 
 from purchase.forms import BasketForm
 from purchase.models import Basket
-
-
-class ProtectedViewsMixin(PermissionRequiredMixin, LoginRequiredMixin):
-    pass
+from purchase.views.utils import ProtectedViewsMixin
 
 
 class NewBasketView(ProtectedViewsMixin, SuccessMessageMixin, CreateView):
@@ -17,6 +13,8 @@ class NewBasketView(ProtectedViewsMixin, SuccessMessageMixin, CreateView):
     form_class = BasketForm
     success_message = "Successfully created basket."
 
+    queryset = Basket.objects.priced()
+
     def get_success_url(self):
         if self.request.user.has_perm("purchase.change_basket"):
             return super().get_success_url()
@@ -29,6 +27,7 @@ class UpdateBasketView(ProtectedViewsMixin, SuccessMessageMixin, UpdateView):
     model = Basket
     form_class = BasketForm
     success_message = "Successfully updated basket."
+    queryset = Basket.objects.priced()
 
 
 class ListBasketsView(ProtectedViewsMixin, ListView):
@@ -36,12 +35,14 @@ class ListBasketsView(ProtectedViewsMixin, ListView):
     model = Basket
     context_object_name = "baskets"
     ordering = "-id"
+    queryset = Basket.objects.priced()
 
 
 class DeleteBasketView(ProtectedViewsMixin, SuccessMessageMixin, DeleteView):
     permission_required = ["purchase.delete_basket"]
     model = Basket
     success_message = "Basket successfully deleted."
+    queryset = Basket.objects.priced()
 
     def get_success_url(self):
         return reverse("purchase:list")

src/purchase/views/reports.py

@@ -0,0 +1,20 @@
+from django.db.models import Sum
+from django.views.generic import TemplateView
+
+from purchase.models import Basket, PaymentMethod, Product
+
+
+class ReportsView(TemplateView):
+    template_name = "purchase/reports.html"
+
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+        context.update(
+            {
+                "total": Basket.objects.priced().aggregate(total=Sum("price"))["total"],
+                "by_day": {},
+                "products": Product.objects.with_turnover().with_sold(),
+                "payment_methods": PaymentMethod.objects.with_turnover(),
+            }
+        )
+        return context

src/purchase/views/utils.py

@@ -0,0 +1,5 @@
+from django.contrib.auth.mixins import LoginRequiredMixin, PermissionRequiredMixin
+
+
+class ProtectedViewsMixin(PermissionRequiredMixin, LoginRequiredMixin):
+    pass