Is this Rails association between Company and Employee valid? - ruby-on-rails-4

Question

I'm writing a basic CRM app to learn Ruby on Rails 4.2, and I have an odd pair of associations (or maybe not so odd). If this were straight SQL and another platform it would be straightforward, but I'm not sure if I'm doing it properly in ROR.
The business requirement is that each company has one or more users. Simple enough. (Relevant portions of the model below.)
user.rb
belongs_to :company
company.rb
has_many :users
An additional requirement is that each company can have one primary user. I need to be able to reference the user's info (name, email, etc) within a Companies index and show view. This is where I'm kind of uncertain. Should the models look like this (it doesn't make sense to me, but I can't think of another way)?:
user.rb
belongs_to :company
company.rb
has_many :users
has_one :user
Here's an abbreviated schema. The user_id in companies is the FK to store the "primary contact":
create_table "companies", force: :cascade do |t|
t.string "companyname"
t.integer "user_id"
end
create_table "users", force: :cascade do |t|
t.string "username"
t.string "email"
t.string "phone"
t.integer "company_id"
end
Thank you for your help.

Answer 1

user.rb
belongs_to :company
company.rb
has_many :users
**belongs_to :primary_user, class_name: "User"**
in company you should have primary_user_id column. You can also define has_one on user like this:
user.rb
belongs_to :company
**has_one :primary_company, class_name: "Company", foreign_key: "primary_user_id"**
company.rb
has_many :users
belongs_to :primary_user, class_name: "User"

Answer 2

user.rb
belongs_to :company
company.rb
has_many :users
Above models are proper. I think for the primary user of a company you can have one more model like primary_user_membership.rb
belongs_to :company
belongs_to :user
create_table "primary_user_memberships", force: :cascade do |t|
t.integer "company_id"
t.integer "user_id"
end

Answer 3

Based on your info, your model is correct.
user.rb
belongs_to :company
company.rb
has_many :users
You can do Company.first.users to see all the first company's users.
Let's say User 1 is the Primary user of Company 1, in rails console, you can check by doing Company.first.users.first
You can also check User 1's info by doing :-
user1 = Company.first.users.first
user1.username
When you generate the User model, you can do: rails g model User username email phone company:belongs_to
Your schema model should look like:-
create_table "companies", force: :cascade do |t|
t.string "companyname"
end
create_table "users", force: :cascade do |t|
t.string "username"
t.string "email"
t.string "phone"
t.integer "company_id"
end