add ability to inspect a cart for the existence of a particular type of item, e.g. PaidCourseRegistration. Only show the 'Shopping Cart' button if there's a PaidCourseRegistration in it.

lms/djangoapps/shoppingcart/context_processor.py

@@ -19,5 +19,8 @@ def user_has_cart_context_processor(request):
         request.user.is_authenticated() and                                # user is logged in and
         settings.FEATURES.get('ENABLE_PAID_COURSE_REGISTRATION') and  # settings enable paid course reg and
         settings.FEATURES.get('ENABLE_SHOPPING_CART') and             # settings enable shopping cart and
-        shoppingcart.models.Order.user_cart_has_items(request.user)        # user's cart has items
+        shoppingcart.models.Order.user_cart_has_items(
+            request.user,
+            shoppingcart.models.PaidCourseRegistration
+        )  # user's cart has PaidCourseRegistrations
     )}

lms/djangoapps/shoppingcart/models.py

@@ -87,15 +87,17 @@ class Order(models.Model):
         return cart_order
 
     @classmethod
-    def user_cart_has_items(cls, user):
+    def user_cart_has_items(cls, user, item_type=None):
         """
         Returns true if the user (anonymous user ok) has
         a cart with items in it.  (Which means it should be displayed.
+        If a item_type is passed in, then we check to see if the cart has at least one of
+        those types of OrderItems
         """
         if not user.is_authenticated():
             return False
         cart = cls.get_cart_for_user(user)
-        return cart.has_items()
+        return cart.has_items(item_type)
 
     @property
     def total_cost(self):
@@ -105,11 +107,19 @@ class Order(models.Model):
         """
         return sum(i.line_cost for i in self.orderitem_set.filter(status=self.status))  # pylint: disable=E1101
 
-    def has_items(self):
+    def has_items(self, item_type=None):
         """
         Does the cart have any items in it?
+        If an item_type is passed in then we check to see if there are any items of that class type
         """
-        return self.orderitem_set.exists()  # pylint: disable=E1101
+        if not item_type:
+            return self.orderitem_set.exists()  # pylint: disable=E1101
+        else:
+            items = self.orderitem_set.all().select_subclasses()
+            for item in items:
+                if isinstance(item, item_type):
+                    return True
+            return False
 
     def clear(self):
         """

lms/djangoapps/shoppingcart/tests/test_models.py

@@ -52,6 +52,21 @@ class OrderTest(ModuleStoreTestCase):
         item = OrderItem(order=cart, user=self.user)
         item.save()
         self.assertTrue(Order.user_cart_has_items(self.user))
+        self.assertFalse(Order.user_cart_has_items(self.user, CertificateItem))
+        self.assertFalse(Order.user_cart_has_items(self.user, PaidCourseRegistration))
+
+    def test_user_cart_has_paid_course_registration_items(self):
+        cart = Order.get_cart_for_user(self.user)
+        item = PaidCourseRegistration(order=cart, user=self.user)
+        item.save()
+        self.assertTrue(Order.user_cart_has_items(self.user, PaidCourseRegistration))
+        self.assertFalse(Order.user_cart_has_items(self.user, CertificateItem))
+
+    def test_user_cart_has_certificate_items(self):
+        cart = Order.get_cart_for_user(self.user)
+        CertificateItem.add_to_order(cart, self.course_key, self.cost, 'honor')
+        self.assertTrue(Order.user_cart_has_items(self.user, CertificateItem))
+        self.assertFalse(Order.user_cart_has_items(self.user, PaidCourseRegistration))
 
     def test_cart_clear(self):
         cart = Order.get_cart_for_user(user=self.user)