generate a 6 digit long unique code for each grouped order

la_chariotte/order/migrations/0025_groupedorder_code.py

@@ -0,0 +1,45 @@
+# Generated by Django 4.2.1 on 2023-08-08 09:20
+
+from django.db import migrations, models
+import base36
+import random
+
+
+def create_code_from_pk(pk):
+    """When a grouped order is created, we compute a unique code that will be used in url path
+    How we generate this code : 
+    1. The instance pk, written in base36 (max 5 digits for now - we assume that there will not be more than 60466175 grouped orders)
+    2. A random int written in base36 (5 digits long)
+    3. Only the 6 first digits of this string
+    The use of pk in the beginning of the string guarantees the uniqueness, and the random part makes that we cannot guess the url path. 
+    """
+    base_36_pk = base36.dumps(pk)
+    random_string = base36.dumps(random.randint(1727605,60466175))  # generates a 5 digits long string
+    return f"{base_36_pk}{random_string}"
+
+def set_code_default(apps, schema_editor):
+    """Provides a default code to existing grouped orders during migration"""
+    GroupedOrder = apps.get_model("order","GroupedOrder")
+    for grouped_order in GroupedOrder.objects.all().iterator():
+        grouped_order.code = create_code_from_pk(grouped_order.pk)
+        grouped_order.save()
+        
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("order", "0024_alter_item_options"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="groupedorder",
+            name="code",
+            field=models.CharField(auto_created=True, null=True),
+        ),
+        migrations.RunPython(set_code_default),
+        migrations.AlterField(
+            model_name="groupedorder",
+            name="code",
+            field=models.CharField(auto_created=True),
+        ),
+    ]

la_chariotte/order/models.py

@@ -1,3 +1,6 @@
+import random
+
+import base36
 from django.core.exceptions import ValidationError
 from django.db import models
 from django.urls import reverse
@@ -5,6 +8,8 @@ from django.utils import timezone
 
 from la_chariotte.settings import AUTH_USER_MODEL
 
+CODE_LENGTH = 6
+
 
 class GroupedOrder(models.Model):
     name = models.CharField(
@@ -20,6 +25,21 @@ class GroupedOrder(models.Model):
     )
     description = models.TextField("Description", null=True, blank=True)
     total_price = models.DecimalField(max_digits=10, decimal_places=2, default=0)
+    code = models.CharField(auto_created=True)
+
+    def create_code_from_pk(self):
+        """When a grouped order is created, we compute a unique code that will be used in url path
+        How we generate this code :
+        1. The instance pk, written in base36 (max 5 digits for now - we assume that there will not be more than 60466175 grouped orders)
+        2. A random int written in base36 (5 digits long)
+        3. Only the 6 first digits of this string
+        The use of pk in the beginning of the string guarantees the uniqueness, and the random part makes that we cannot guess the url path.
+        """
+        base_36_pk = base36.dumps(self.pk)
+        random_string = base36.dumps(
+            random.randint(pow(36, CODE_LENGTH - 2), pow(36, CODE_LENGTH - 1) - 1)
+        )  # generates a 5 digits long string
+        self.code = f"{base_36_pk}{random_string}"[:CODE_LENGTH]
 
     def compute_total_price(self):
         price = 0

la_chariotte/order/tests/test_models.py

@@ -1,10 +1,14 @@
 import datetime
 
+import pytest
 from django.contrib import auth
 from django.urls import reverse
 from django.utils import timezone
 
-from la_chariotte.order.models import GroupedOrder, Item
+from la_chariotte.order.models import CODE_LENGTH, GroupedOrder, Item
+from la_chariotte.order.tests.utils import create_grouped_order
+
+pytestmark = pytest.mark.django_db
 
 
 class TestGroupedOrderModel:
@@ -124,6 +128,15 @@ class TestGroupedOrderModel:
         "La date de livraison ne doit pas être dans le passé" in response.content.decode()
         assert GroupedOrder.objects.count() == 0
 
+    def test_create_unique_code_from_pk(self, client_log):
+        grouped_order = create_grouped_order(
+            days_before_delivery_date=5,
+            days_before_deadline=2,
+            name="future",
+            orga_user=auth.get_user(client_log),
+        )
+        assert len(grouped_order.code) == CODE_LENGTH
+
 
 class TestItemModel:
     """Tests for Item model"""

la_chariotte/order/tests/test_views/test_views_grouped_order.py

@@ -791,6 +791,7 @@ class TestGroupedOrderCreateView:
         assert response.status_code == 302
         assert response.url.endswith("gerer-produits")
         assert models.GroupedOrder.objects.count() == 1
+        assert models.GroupedOrder.objects.first().code != ""
 
     def test_create_grouped_order__anonymous_user(self, client):
         create_gorder_url = reverse("order:create_grouped_order")

la_chariotte/order/tests/utils.py

@@ -18,9 +18,11 @@ def create_grouped_order(
     """
     date = timezone.now().date() + datetime.timedelta(days=days_before_delivery_date)
     deadline = timezone.now() + datetime.timedelta(days=days_before_deadline)
-    return models.GroupedOrder.objects.create(
+    grouped_order = models.GroupedOrder.objects.create(
         name=name, orga=orga_user, delivery_date=date, deadline=deadline
     )
+    grouped_order.create_code_from_pk()
+    return grouped_order
 
 
 def order_items_in_grouped_order(grouped_order):

la_chariotte/order/views/grouped_order.py

@@ -122,6 +122,12 @@ class GroupedOrderCreateView(LoginRequiredMixin, generic.CreateView):
         kwargs["user"] = self.request.user
         return kwargs
 
+    def form_valid(self, form):
+        """If the form is valid, generate a unique code and save"""
+        self.object = form.save()
+        self.object.create_code_from_pk()
+        return super().form_valid(form)
+
 
 class GroupedOrderUpdateView(UserPassesTestMixin, generic.UpdateView):
     """View for updating a grouped order"""

requirements.txt

@@ -13,6 +13,8 @@ asn1crypto==1.5.1
     #   oscrypto
     #   pyhanko
     #   pyhanko-certvalidator
+base36==0.1.1
+    # à la main
 certifi==2023.5.7
     # via
     #   requests