Knowledge is power
Although Sencha Cmd is a very useful tool for application scaffolding, creating view, controllers and models, sometimes it is faster to use a single-file app. It is especially useful for fast testing, prototyping or concept proof. Read how to do it.
In essence, factory functions are class methods that manufacture items or other properties during the instantiation of the class. This article explains pros and cons of factory function and how to use them correctly.
Imagine that you have a one-to-many relationship in your database, for example, you have table person in which you keep personal data (first, middle, last names, etc.) and you have table phone where you keep phone numbers (phone type, phone number).
It is quite common to have person:phones, company:phones, order:items, invoice:items, etc relationships.