From 746df67c90640afb683b2561488cc56898614185 Mon Sep 17 00:00:00 2001
From: "Nimrod S. Kerrett" <unclezzzen@gmail.com>
Date: Thu, 17 May 2012 22:12:34 +0700
Subject: [PATCH 1/3] update() logic

Seems like update() did nothing before. [?!?]
Now it adds the item if not found, removes it if quantity is 0,
and tries to act sanely when something goes wrong :)
---
 cart/cart.py | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/cart/cart.py b/cart/cart.py
index ff08dc1..5761615 100644
--- a/cart/cart.py
+++ b/cart/cart.py
@@ -66,9 +66,18 @@ def update(self, product, quantity, unit_price=None):
                 cart=self.cart,
                 product=product,
             )
+            if quantity:
+                item.quantity = quantity
+                if unit_price:
+                    item.unit_price = unit_price
+            else:
+                item.delete()
         except models.Item.DoesNotExist:
-            raise ItemDoesNotExist
-            
+            if unit_price:
+                self.add(product, unit_price, quantity)
+            else:
+                raise ItemDoesNotExist
+
     def count(self):
         result = 0
         for item in self.cart.item_set.all():

From 06c079e6d53e7595401d52eee7fb27eaf06520d7 Mon Sep 17 00:00:00 2001
From: "Nimrod S. Kerrett" <unclezzzen@gmail.com>
Date: Fri, 18 May 2012 01:44:05 +0700
Subject: [PATCH 2/3] Oops, forgot the save :s

---
 cart/cart.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/cart/cart.py b/cart/cart.py
index 5761615..fcfedbf 100644
--- a/cart/cart.py
+++ b/cart/cart.py
@@ -70,6 +70,7 @@ def update(self, product, quantity, unit_price=None):
                 item.quantity = quantity
                 if unit_price:
                     item.unit_price = unit_price
+                item.save()
             else:
                 item.delete()
         except models.Item.DoesNotExist:

From 547ea66d8dce79841a595576c0766d53c021ea6e Mon Sep 17 00:00:00 2001
From: "Nimrod S. Kerrett" <unclezzzen@gmail.com>
Date: Fri, 25 May 2012 03:26:22 +0700
Subject: [PATCH 3/3] Ignore 0->0 updates (don't add empty item)

Turns our users actually do this in real life :)
---
 cart/cart.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/cart/cart.py b/cart/cart.py
index fcfedbf..b321113 100644
--- a/cart/cart.py
+++ b/cart/cart.py
@@ -75,7 +75,8 @@ def update(self, product, quantity, unit_price=None):
                 item.delete()
         except models.Item.DoesNotExist:
             if unit_price:
-                self.add(product, unit_price, quantity)
+                if quantity: # Maybe user updated 0 to 0. Happens
+                    self.add(product, unit_price, quantity)
             else:
                 raise ItemDoesNotExist