Porting the MVC Music Store to Raven: ShoppingCartController
The ShoppingCartController is heavily affected by the changes we made to the ShoppingCart. Let us look at those changes, starting from Index():
On the left, we have the original version. You can see that it executes two different queries to process this order, the Raven version, however, is executing only a single query, in the FindShoppingCart method:
This just implements the logic of loading the cart from Raven or creating a new cart (with the specified shopping cart id), note that we don’t save the new cart to the database here, merely associate the new cart with the session. There is no need to save, since it contains no meaningful data at this point. When we will call SaveChanges(), the new cart will be send to Raven for storage.
Let us look at the AddToCart action now:
On the left, you can see the old version, and on the right, you see the Raven version. They are pretty similar, except that in the Raven case, the shopping cart’s AddToCart is concerned solely with adding a new item to the cart or incrementing the quantity of an existing item. There is absolutely no data access in the Raven’s version of ShoppingCart.AddToCart.
One major difference is that the Raven approach is calling the session.SaveChanges() in the action code. The reason for that is simple, it is the proper place for this, as the calling code, it is responsible for the environment, including saving when needed.
Raven’s code is pretty easy to follow here, I think. There is just one thing that you should note, the last line is pretty strange id.Split ? Why do we do that?
The reason for that is that Raven uses id that looks like this: “albums/616” and the DeleteId is used by the calling javascript code to find an element by its id. An element can’t contain a ‘/’ in it, so we strip it away and only send the number part of the id. This is safe to do since we only deal with albums here.
Again, this is about as simple as you can make it, so I’ll note only that Raven’s approach can benefit from the unit of work cache, and the old code approach can’t.
In my next post, we will deal with the order process.