fix(stripe): store customer ID in profile to prevent duplicate customers

web/tests/test_donation_views.py

@@ -0,0 +1,33 @@
+import json
+from unittest.mock import Mock, patch
+
+from django.contrib.auth.models import User
+from django.test import Client, TestCase
+from django.urls import reverse
+
+from ..models import MembershipPlan, Profile, UserMembership
+
+
+class CreateDonationSubscriptionViewTests(TestCase):
+    def setUp(self):
+        self.client = Client()
+        self.user = User.objects.create_user(username="test", email="test@example.com", password="pass")
+        self.profile, _ = Profile.objects.get_or_create(user=self.user, defaults={"is_teacher": False})
+        self.plan = MembershipPlan.objects.create(
+            name="Basic", slug="basic", description="Basic plan", price_monthly=0, price_yearly=0
+        )
+
+    @patch("stripe.PaymentIntent.create")
+    @patch("stripe.Customer.retrieve")
+    def test_reuses_existing_stripe_customer(self, mock_retrieve, mock_payment_intent):
+        UserMembership.objects.create(user=self.user, plan=self.plan, stripe_customer_id="cus_existing")
+        mock_retrieve.return_value = Mock(id="cus_existing")
+        mock_payment_intent.return_value = Mock(client_secret="secret", id="pi_123")
+        self.client.login(username="test", password="pass")
+        response = self.client.post(
+            reverse("create_donation_subscription"),
+            data=json.dumps({"amount": "10.00", "email": "test@example.com"}),
+            content_type="application/json",
+        )
+        self.assertEqual(response.status_code, 200)
+        mock_retrieve.assert_called_once_with("cus_existing")

web/views.py

@@ -171,6 +171,7 @@
     TeamInvite,
     TimeSlot,
     UserBadge,
+    UserMembership,
     VideoRequest,
     VirtualClassroom,
     VirtualClassroomCustomization,
@@ -5617,11 +5618,15 @@ def create_donation_subscription(request: HttpRequest) -> JsonResponse:
         # Create or get customer
         customer = None
         # Try to retrieve existing customer for authenticated users
-        if request.user.is_authenticated and hasattr(request.user, "stripe_customer_id"):
-            from contextlib import suppress
+        if request.user.is_authenticated:
+            try:
+                membership = request.user.membership
+                if membership.stripe_customer_id:
+                    customer = stripe.Customer.retrieve(membership.stripe_customer_id)
+            except (UserMembership.DoesNotExist, stripe.error.InvalidRequestError):
+                # No membership or invalid customer ID
+                customer = None
 
-            with suppress(stripe.error.InvalidRequestError):
-                customer = stripe.Customer.retrieve(request.user.stripe_customer_id)
         # Create new customer if needed
         if not customer:
             customer = stripe.Customer.create(
@@ -5631,8 +5636,13 @@ def create_donation_subscription(request: HttpRequest) -> JsonResponse:
                 },
             )
             if request.user.is_authenticated:
-                request.user.stripe_customer_id = customer.id
-                request.user.save()
+                # Store customer ID in user membership
+                membership, _ = UserMembership.objects.get_or_create(
+                    user=request.user, defaults={"plan_id": 1, "stripe_customer_id": customer.id}
+                )
+                if not membership.stripe_customer_id:
+                    membership.stripe_customer_id = customer.id
+                    membership.save()
 
         # Create a PaymentIntent for the first payment with setup_future_usage
         payment_intent = stripe.PaymentIntent.create(