How does ActiveRecord::Relation get added to Rails' models and why does each model have individual Relation class?

Question

Suppose I have a Rails model: class Project < ActiveRecord::Base

In the Rails console:

> Project.all
=> #

        

Answer 1

There are actually two questions you are asking:

1. How does it work?
2. Why is it like that? (What for?)

@arieljuod has already given you some explanations and a link.

However the second question is still unanswered.

There is another similar question exists which I hope will help you find all the answers:

How can an ActiveRecord::Relation object call class methods

It looks like the two questions (by the link and yours one) answer each other )

Take a look at @nikita-shilnikov's answer. Good luck in your investigation!