How to use Associations

[devyani9999]

Hi,
I am trying to use associations with table-less models. I do not find how to use associations in github documentation nor I am able to find any tutorial regarding it.
Suppose, I am using belongs_to relationship(like User belongs_to a Category). How I am supposed to get Category.all or find a category object given a category_id. Do I need to override all these methods?
If you have any working example or documentation for the same, please share.
For details, here is the stackoverflow question regarding the same.