Maps model classes to database records. Kales follows some conventions when dealing with models:

Represents an association where a model A's table contains a foreign key to another model B's ApplicationRecord object, in a "A belongs to B" fashion.

Represents a one-to-many association between models F and T respectively

Data type that represents ApplicationRecord.id. Can be either NoneId or RecordId to represent the fact that an ID may or may not exist depending on whether the record has been previously persisted to the DB or not.

ID for records that are only in-memory and not persisted in the database yet (or at all) Since ApplicationRecord IDs are generated (auto-increment), they should not be set when instantiating an object and instead auto assigned when persisting it to the database.

ID for records that have been previously persisted to the database and have an auto generated value.