Include last-modified in cache

src/purchase/admin.py

@@ -3,7 +3,7 @@ from django.contrib.admin import register
 from django.utils.translation import gettext_lazy as _
 from solo.admin import SingletonModelAdmin
 
-from purchase.models import Basket, BasketItem, CacheEtag, PaymentMethod, Product
+from purchase.models import Basket, BasketItem, Cache, PaymentMethod, Product
 from purchase.templatetags.purchase import currency
 
 
@@ -73,4 +73,4 @@ class BasketAdmin(admin.ModelAdmin):
         return currency(instance.price)
 
 
-admin.site.register(CacheEtag, SingletonModelAdmin)
+admin.site.register(Cache, SingletonModelAdmin)

src/purchase/migrations/0011_rename_cacheetag_cache.py

@@ -0,0 +1,17 @@
+# Generated by Django 4.1.1 on 2022-09-25 19:41
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("purchase", "0010_rename_basketitemetag_cacheetag"),
+    ]
+
+    operations = [
+        migrations.RenameModel(
+            old_name="CacheEtag",
+            new_name="Cache",
+        ),
+    ]

src/purchase/migrations/0012_rename_value_cache_etag_cache_last_modified.py

@@ -0,0 +1,23 @@
+# Generated by Django 4.1.1 on 2022-09-25 19:45
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("purchase", "0011_rename_cacheetag_cache"),
+    ]
+
+    operations = [
+        migrations.RenameField(
+            model_name="cache",
+            old_name="value",
+            new_name="etag",
+        ),
+        migrations.AddField(
+            model_name="cache",
+            name="last_modified",
+            field=models.DateTimeField(auto_now=True),
+        ),
+    ]

src/purchase/models.py

@@ -224,12 +224,21 @@ class BasketItem(Model):
         ]
 
 
-class CacheEtag(SingletonModel):
-    value = models.UUIDField(default=uuid.uuid4)
+class Cache(SingletonModel):
+    etag = models.UUIDField(default=uuid.uuid4)
+    last_modified = models.DateTimeField(auto_now=True)
 
     def __str__(self) -> str:
-        return str(self.value)
+        return str(self.etag)
 
     def refresh(self):
-        self.value = uuid.uuid4()
+        self.etag = uuid.uuid4()
         self.save()
+
+
+def reports_etag(request):
+    return str(Cache.get_solo().etag)
+
+
+def reports_last_modified(request):
+    return Cache.get_solo().last_modified

src/purchase/signals.py

@@ -1,4 +1,4 @@
 def basket_item_on_save(sender, **kwargs):
-    from purchase.models import CacheEtag
+    from purchase.models import Cache
 
-    CacheEtag.get_solo().refresh()
+    Cache.get_solo().refresh()

src/purchase/views/basket.py

@@ -8,8 +8,7 @@ from django.utils.translation import gettext_lazy as _
 from django.views.decorators.http import condition, require_http_methods
 
 from purchase.forms import BasketForm
-from purchase.models import Basket
-from purchase.views.reports import reports_etag
+from purchase.models import Basket, reports_etag, reports_last_modified
 
 
 @require_http_methods(["GET", "POST"])
@@ -50,7 +49,7 @@ def update_basket(request: HttpRequest, pk: int) -> HttpResponse:
 
 
 @permission_required("purchase.view_basket")
-@condition(etag_func=reports_etag)
+@condition(etag_func=reports_etag, last_modified_func=reports_last_modified)
 def list_baskets(request: HttpRequest) -> HttpResponse:
     context = {"baskets": Basket.objects.priced().order_by("-id")}
     return TemplateResponse(request, "purchase/basket_list.html", context)

src/purchase/views/reports.py

@@ -18,17 +18,20 @@ from matplotlib.container import BarContainer
 from matplotlib.dates import AutoDateLocator, ConciseDateFormatter, HourLocator
 from matplotlib.figure import Figure
 
-from purchase.models import Basket, CacheEtag, PaymentMethod, Product, ProductQuerySet
+from purchase.models import (
+    Basket,
+    PaymentMethod,
+    Product,
+    ProductQuerySet,
+    reports_etag,
+    reports_last_modified,
+)
 
 matplotlib.use("SVG")
 
 
-def reports_etag(request):
-    return str(CacheEtag.get_solo().value)
-
-
 @permission_required("purchase.view_basket")
-@condition(etag_func=reports_etag)
+@condition(etag_func=reports_etag, last_modified_func=reports_last_modified)
 def products_plots_view(request):
     products = Product.objects.with_turnover().with_sold()
     (
@@ -43,7 +46,7 @@ def products_plots_view(request):
 
 
 @permission_required("purchase.view_basket")
-@condition(etag_func=reports_etag)
+@condition(etag_func=reports_etag, last_modified_func=reports_last_modified)
 def by_hour_plot_view(request):
     baskets = list(Basket.objects.priced().order_by("created_at"))
     context = {
@@ -53,7 +56,7 @@ def by_hour_plot_view(request):
 
 
 @permission_required("purchase.view_basket")
-@condition(etag_func=reports_etag)
+@condition(etag_func=reports_etag, last_modified_func=reports_last_modified)
 def reports(request):
     template_name = "purchase/reports.html"
     baskets = list(Basket.objects.priced().order_by("created_at"))