server/order: fix invoice handling when there are only prorations

server/polar/order/service.py

@@ -215,14 +215,36 @@ async def create_order_from_stripe(
         for line in invoice.lines.data:
             if not line.proration and line.price is not None:
                 stripe_price_ids.add(line.price.id)
-        if len(stripe_price_ids) != 1:
+
+        product_price: ProductPrice | None = None
+        # For invoices with only one line item, get the price from the line item
+        if len(stripe_price_ids) == 1:
+            stripe_price_id = stripe_price_ids.pop()
+            product_price = await product_price_service.get_by_stripe_price_id(
+                session, stripe_price_id
+            )
+            if product_price is None:
+                raise ProductPriceDoesNotExist(invoice.id, stripe_price_id)
+        # For invoices with only prorations, try to get the price from the subscription metadata
+        elif len(stripe_price_ids) == 0:
+            if (
+                invoice.subscription_details is None
+                or invoice.subscription_details.metadata is None
+                or (
+                    (price_id := invoice.subscription_details.metadata.get("price_id"))
+                    is None
+                )
+            ):
+                raise CantDetermineInvoicePrice(invoice.id)
+            product_price = await product_price_service.get_by_id(
+                session, uuid.UUID(price_id)
+            )
+            if product_price is None:
+                raise CantDetermineInvoicePrice(invoice.id)
+        # For invoices with multiple line items, we can't determine the price
+        else:
             raise CantDetermineInvoicePrice(invoice.id)
-        stripe_price_id = stripe_price_ids.pop()
-        product_price = await product_price_service.get_by_stripe_price_id(
-            session, stripe_price_id
-        )
-        if product_price is None:
-            raise ProductPriceDoesNotExist(invoice.id, stripe_price_id)
+
         product = product_price.product
 
         user: User | None = None

server/tests/order/test_service.py

@@ -1,3 +1,4 @@
+from typing import Any
 from unittest.mock import AsyncMock
 
 import pytest
@@ -43,6 +44,7 @@ def construct_stripe_invoice(
     tax: int = 2000,
     charge_id: str = "CHARGE_ID",
     subscription_id: str | None = "SUBSCRIPTION_ID",
+    subscription_details: dict[str, Any] | None = None,
     customer_id: str = "CUSTOMER_ID",
     lines: list[tuple[str, bool]] = [("PRICE_ID", False)],
     metadata: dict[str, str] = {},
@@ -56,6 +58,7 @@ def construct_stripe_invoice(
             "currency": "usd",
             "charge": charge_id,
             "subscription": subscription_id,
+            "subscription_details": subscription_details,
             "customer": customer_id,
             "lines": {
                 "data": [
@@ -211,7 +214,6 @@ async def test_not_a_order_invoice(
         "lines",
         (
             [],
-            [("PRICE_1", True), ("PRICE_2", True)],
             [("PRICE_1", False), ("PRICE_2", False)],
         ),
     )
@@ -303,6 +305,37 @@ async def test_subscription_proration(
         assert order.subscription == subscription
         assert order.user.stripe_customer_id == invoice.customer
 
+    async def test_subscription_only_proration(
+        self,
+        session: AsyncSession,
+        save_fixture: SaveFixture,
+        subscription: Subscription,
+        product: Product,
+    ) -> None:
+        invoice = construct_stripe_invoice(
+            subscription_id=subscription.stripe_subscription_id,
+            lines=[
+                ("PRICE_1", True),
+                ("PRICE_2", True),
+            ],
+            subscription_details={"metadata": {"price_id": str(product.prices[0].id)}},
+        )
+
+        payment_transaction = await create_transaction(
+            save_fixture, type=TransactionType.payment
+        )
+        payment_transaction.charge_id = "CHARGE_ID"
+        await save_fixture(payment_transaction)
+
+        order = await order_service.create_order_from_stripe(session, invoice=invoice)
+
+        assert order.amount == invoice.total - (invoice.tax or 0)
+        assert order.user.id == subscription.user_id
+        assert order.product == product
+        assert order.product_price == product.prices[0]
+        assert order.subscription == subscription
+        assert order.user.stripe_customer_id == invoice.customer
+
     async def test_subscription_with_account(
         self,
         enqueue_job_mock: AsyncMock,