Adds the checkout API to the OpenAPI-compatible API list (#3178)

Author: jkachel

ecommerce/api.py

@@ -50,6 +50,9 @@
 from flexiblepricing.api import determine_courseware_flexible_price_discount
 from hubspot_sync.task_helpers import sync_hubspot_deal
 from main.constants import (
+    USER_MSG_TYPE_B2B_ERROR_MISSING_ENROLLMENT_CODE,
+    USER_MSG_TYPE_B2B_INVALID_BASKET,
+    USER_MSG_TYPE_BASKET_EMPTY,
     USER_MSG_TYPE_COURSE_NON_UPGRADABLE,
     USER_MSG_TYPE_DISCOUNT_INVALID,
     USER_MSG_TYPE_ENROLL_BLOCKED,
@@ -74,6 +77,7 @@ def generate_checkout_payload(request):  # noqa: PLR0911
     if basket.has_user_blocked_products(request.user):
         return {
             "country_blocked": True,
+            "error": USER_MSG_TYPE_ENROLL_BLOCKED,
             "response": redirect_with_user_message(
                 reverse("user-dashboard"),
                 {"type": USER_MSG_TYPE_ENROLL_BLOCKED},
@@ -83,6 +87,7 @@ def generate_checkout_payload(request):  # noqa: PLR0911
     if basket.has_user_purchased_same_courserun(request.user):
         return {
             "purchased_same_courserun": True,
+            "error": USER_MSG_TYPE_ENROLL_DUPLICATED,
             "response": redirect_with_user_message(
                 reverse("cart"),
                 {"type": USER_MSG_TYPE_ENROLL_DUPLICATED},
@@ -92,6 +97,7 @@ def generate_checkout_payload(request):  # noqa: PLR0911
     if basket.has_user_purchased_non_upgradable_courserun():
         return {
             "purchased_non_upgradeable_courserun": True,
+            "error": USER_MSG_TYPE_COURSE_NON_UPGRADABLE,
             "response": redirect_with_user_message(
                 reverse("cart"),
                 {"type": USER_MSG_TYPE_COURSE_NON_UPGRADABLE},
@@ -104,6 +110,7 @@ def generate_checkout_payload(request):  # noqa: PLR0911
         apply_user_discounts(request)
         return {
             "invalid_discounts": True,
+            "error": USER_MSG_TYPE_DISCOUNT_INVALID,
             "response": redirect_with_user_message(
                 reverse("cart"),
                 {"type": USER_MSG_TYPE_DISCOUNT_INVALID},
@@ -115,6 +122,7 @@ def generate_checkout_payload(request):  # noqa: PLR0911
     if not is_discount_supplied_for_b2b_purchase(request, active_contracts):
         return {
             "invalid_discounts": True,
+            "error": USER_MSG_TYPE_B2B_ERROR_MISSING_ENROLLMENT_CODE,
             "response": redirect_with_user_message(
                 reverse("cart"),
                 {"type": USER_MSG_TYPE_REQUIRED_ENROLLMENT_CODE_EMPTY},
@@ -124,12 +132,23 @@ def generate_checkout_payload(request):  # noqa: PLR0911
     if not validate_basket_for_b2b_purchase(request, active_contracts):
         return {
             "invalid_discounts": True,
+            "error": USER_MSG_TYPE_B2B_INVALID_BASKET,
             "response": redirect_with_user_message(
                 reverse("cart"),
                 {"type": USER_MSG_TYPE_DISCOUNT_INVALID},
             ),
         }
 
+    if not basket.basket_items.count():
+        return {
+            "basket_empty": True,
+            "error": USER_MSG_TYPE_BASKET_EMPTY,
+            "response": redirect_with_user_message(
+                reverse("cart"),
+                {"type": USER_MSG_TYPE_BASKET_EMPTY},
+            ),
+        }
+
     order = PendingOrder.create_from_basket(basket)
     total_price = 0
 

ecommerce/serializers/v0/__init__.py

@@ -22,13 +22,24 @@
 )
 from ecommerce.models import Basket, BasketItem, Order, Product
 from flexiblepricing.api import determine_courseware_flexible_price_discount
+from main.constants import (
+    USER_MSG_TYPE_B2B_ERROR_MISSING_ENROLLMENT_CODE,
+    USER_MSG_TYPE_B2B_INVALID_BASKET,
+    USER_MSG_TYPE_BASKET_EMPTY,
+    USER_MSG_TYPE_COURSE_NON_UPGRADABLE,
+    USER_MSG_TYPE_DISCOUNT_INVALID,
+    USER_MSG_TYPE_ENROLL_BLOCKED,
+    USER_MSG_TYPE_ENROLL_DUPLICATED,
+)
 from main.settings import TIME_ZONE
 from users.serializers import ExtendedLegalAddressSerializer, UserSerializer
 
 User = get_user_model()
 
 
 class V0DiscountSerializer(serializers.ModelSerializer):
+    """Serializes a discount."""
+
     class Meta:
         model = models.Discount
         fields = [
@@ -911,3 +922,53 @@ def get_purchaser(self, instance):
     class Meta:
         fields = ["purchaser", "lines", "coupon", "order", "receipt"]
         model = models.Order
+
+
+class CheckoutPayloadSerializer(serializers.Serializer):
+    """Serializes the payload for the checkout data."""
+
+    no_checkout = serializers.BooleanField(
+        read_only=True,
+        required=False,
+        default=False,
+        help_text="Set if the order was automatically completed and no checkout process is required.",
+    )
+    url = serializers.CharField(
+        read_only=True,
+        required=False,
+        default="",
+        help_text="The URL to POST the form to.",
+    )
+    method = serializers.CharField(
+        read_only=True,
+        required=False,
+        default="POST",
+        help_text="The method to use for the checkout form (always POST).",
+    )
+    payload = serializers.JSONField(
+        read_only=True, required=False, default={}, help_text="The data for the form."
+    )
+    order_id = serializers.IntegerField(
+        read_only=True,
+        required=False,
+        default=0,
+        help_text="If the order was automatically completed, the ID of the new order.",
+    )
+    error = serializers.ChoiceField(
+        read_only=True,
+        required=False,
+        default=None,
+        help_text="Error message for the order, if there is one.",
+        choices=(
+            USER_MSG_TYPE_ENROLL_BLOCKED,
+            USER_MSG_TYPE_ENROLL_DUPLICATED,
+            USER_MSG_TYPE_COURSE_NON_UPGRADABLE,
+            USER_MSG_TYPE_DISCOUNT_INVALID,
+            USER_MSG_TYPE_B2B_ERROR_MISSING_ENROLLMENT_CODE,
+            USER_MSG_TYPE_B2B_INVALID_BASKET,
+            USER_MSG_TYPE_BASKET_EMPTY,
+        ),
+    )
+
+    class Meta:
+        fields = ["no_checkout", "url", "method", "payload", "order_id", "error"]

ecommerce/views/v0/__init__.py

@@ -6,6 +6,7 @@
 
 import django_filters
 from django.contrib.auth import get_user_model
+from django.core.exceptions import ObjectDoesNotExist
 from django.db.models import Count, Q
 from django.shortcuts import redirect
 from django_filters import rest_framework as filters
@@ -31,6 +32,7 @@
 from ecommerce.api import (
     apply_discount_to_basket,
     establish_basket,
+    generate_checkout_payload,
     generate_discount_code,
     get_auto_apply_discounts_for_basket,
 )
@@ -48,6 +50,7 @@
     BasketItemSerializer,
     BasketWithProductSerializer,
     BulkDiscountSerializer,
+    CheckoutPayloadSerializer,
     DiscountProductSerializer,
     DiscountRedemptionSerializer,
     ProductFlexiblePriceSerializer,
@@ -400,6 +403,37 @@ def clear_basket(request):
     return Response(None, status=status.HTTP_204_NO_CONTENT)
 
 
+@extend_schema(
+    description=(
+        "Returns the payload necessary to redirect the user to CyberSource for payment."
+    ),
+    methods=["GET"],
+    responses=CheckoutPayloadSerializer,
+)
+@api_view(["GET"])
+@permission_classes([IsAuthenticated])
+def checkout_basket(request):
+    """
+    Generate the data for checkout and return it.
+
+    This gathers and converts the data in the current user's Basket, makes it
+    into an Order, and returns the form data needed to start the checkout process
+    in CyberSource. The frontend app then needs to pull the data into a form and
+    POST it to the appropriate URL to send the user over to CyberSource so we can
+    collect payment.
+    """
+
+    try:
+        payload = generate_checkout_payload(request)
+        req_status = (
+            status.HTTP_400_BAD_REQUEST if "error" in payload else status.HTTP_200_OK
+        )
+
+        return Response(CheckoutPayloadSerializer(payload).data, status=req_status)
+    except ObjectDoesNotExist:
+        return Response("No basket", status=status.HTTP_406_NOT_ACCEPTABLE)
+
+
 class ProductsPagination(LimitOffsetPagination):
     """Sets a default limit for the product list API."""
 

ecommerce/views/v0/urls.py

@@ -13,6 +13,7 @@
     NestedUserDiscountViewSet,
     ProductViewSet,
     add_discount_to_basket,
+    checkout_basket,
     clear_basket,
     create_basket_from_product,
     create_basket_from_product_with_discount,
@@ -87,6 +88,11 @@
         add_discount_to_basket,
         name="baskets_api-add_discount",
     ),
+    path(
+        "baskets/checkout/",
+        checkout_basket,
+        name="baskets_api-checkout",
+    ),
     re_path(
         r"^",
         include(