Locating and Traversing Records
In the Depot application, LineItems have direct relationships to three other models: Cart, Order, and Product. Additionally, models can have indirect relationships mediated by resource objects. The relationship between Orders and Products through LineItems is an example of such a relationship.
All of this is made possible through IDs.
Identifying Individual Rows
Active Record classes correspond to tables in a database. Instances of a class correspond to the individual rows in a database table. Calling Order.find(1), for instance, returns an instance of an Order class containing the data in the row with the primary key of 1.
If you’re creating a new schema for a Rails application, you’ll probably want to go ...
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