Question

I have a User model, Person model and Company model.

a User has many companies through Person and vice versa.

But i would like to be able to populate People and Companies that are not tied to Users that can be tied later.

class User < ActiveRecord::Base
  attr_accessible :name
  has_many :people
  has_many :companies, :through => :people
end

class Person < ActiveRecord::Base
  attr_accessible :user_id, :company_id
  belongs_to :users
  belongs_to :companies
end

class Company < ActiveRecord::Base
  attr_accessible :name
  has_many :people
  has_many :users, :through => :person
end

now in the console i want to be doing the following

User.find(1).companies

then it should find me the companies in which user(1) is a person of interest.

Have I got this wrong, is there a small change that I should be making.

Answer 1

Your Person model can’t directly “belong_to” more than one, your belongs_to :users and belongs_to :companies associations won’t work that way. Companies-to-people need to be connected through another join table that describes the relationship between them, for example Employment which points to one instance of each model:

class Person < ActiveRecord::Base
  has_many :employments
  has_many :companies, :through => :employments
end

class Employment < ActiveRecord::Base
  belongs_to :person
  belongs_to :company
end

class Company < ActiveRecord::Base
  has_many :employments
  has_many :people, :through => :employments
end

You can then use the :through option to associate the many companies/people on the other side of that employment relationship in the middle.

Similarly, if a Person can be owned by more than one User then you will need a join model between those two entities as well.