Question

For practice I’m writing a shopping website where we have tables User and Item. A user obviously has_many items (when they are added to their basket), but the item, it belongs_to a User, even though many users will have the same item in their basket?

Furthermore, what if I want a list of items a user has added to their basket, but also a list of items they have viewed (for making suggestions based on searches), would it be better to have some ‘through’ tables: Basket and Viewed?

Answer 1

When you have this many-to-many relationships, you can use the HABTM schema:

Class User...
has_and_belongs_to_many :items

However, most of the time webshops use orderlines to keep up with items that users are purchasing. This means that an ‘user’ ‘has_many’ ‘orderlines’, an ‘item’ ‘has_many’ ‘orderlines’, an ‘orderline’ ‘belongs_to’ an ‘user’ and to an ‘item’.

And maybe your orderlines will just be copies of items, and won’t have a direct link because you don’t want to alter the orderline after they have been processed. It really depends on the focus of your shop which scheme suits your needs.

Try to find some examples on the web and think about how you want to handle items, orders and baskets.