Django 2 by Example

Storing shopping carts in sessions

We need to create a simple structure that can be serialized to JSON for storing cart items in a session. The cart has to include the following data for each item contained in it:

• The ID of a Product instance
• Quantity selected for the product
• Unit price for the product

Since product prices may vary, we take the approach of storing the product's price along with the product itself when it's added to the cart. By doing so, we use the current price of the product when users add it to their cart, no matter if the product's price is changed afterwards.

Now, you have to build functionality to create carts and associate them with sessions. The shopping cart has to work as follows:

• When a cart is needed, we check ...