ActiveRecord association model

Question

I am new to rails and read this guide to get all the info so far.

I have a simple scenario and want to make sure whether or not my associations will work fine.

Scenario: User logs in -> sets up many groups -> each group has many employees

User model:

class User < ActiveRecord::Base
    has_many :groups
end

Group model:

class Group < ActiveRecord::Base
    belongs_to :user
    has_many :employees
end

Employee model:

class Employee < ActiveRecord::Base
    has_many :groups
    belongs_to :group
end

Questions

• Will this work for the scenario I mentioned?
• I am confused about how to get all Employees under a User. What would be the code for that?
• If I need typical CRUD for all these models then would would be in my Action? index/create/update/destroy? Can someone point me to a good guide on actions?

Answer 1

You have it together, for the most part, but I think you need to look at has_and_belongs_to_many (which you will frequently see abbreviated as habtm.) Index, create, update, and destroy would be your CRUD list for Ruby on Rails. As for a good guide, I like Agile Web Development With Rails, by Dave Thomas. (When I'm picking up a new topic, I like books - electronic or otherwise.) It's available online through The Practical Programmers. The question about "what's a good guide" is pretty subjective, so caveat emptor.

Answer 2

I also like the has_many through --

class User < ActiveRecord::Base
    has_many :groups
    has_many :employees, :through=>:groups
end

Then you can go:

user = User.find(23)
user.employees.do_something

Otherwise, you could loop through your groups and its employees (kinda ugly, but will work)

User.first.groups.each{|group| group.employees.each{|employee| puts employee.name}}