模型协会-has_many：through

Question

I have three models - Company , User and CompanyUser . The associations are as follows.

Company.rb

  has_many :company_users
  has_many :users, :through => :company_users

User.rb

  has_many :company_users, :dependent => :destroy
  belongs_to :company

CompanyUser.rb

  belongs_to :company
  belongs_to :user

For fetching current_user.company, what moddifications are to be made in the model association?

Any help would be appreciated.

Answer 1

It should be:

has_many :companies, through: :company_users

A has_many :through association is often used to set up a many-to-many connection with another model. This association indicates that the declaring model can be matched with zero or more instances of another model by proceeding through a third model.

So if you are creating three models and making a has_many :through association I believe that User will have many Companies and Company will have many Users .

But if you need that the user belongs to only one company instead of creating the third model save the company_id in the users table itself.

Update:

Now as your scenario is A company can have may users and User belongs to a single company , you need two models: User and Company . Your User model should have an attribute company_id and then company_id should be saved in users table only. Then the associations as follows:

class User < ActiveRecord::Base
  belongs_to :company
end

class Company < ActiveRecord::Base
  has_many :users
end

Then you can do current_user.company

You can get more information on associations in the RailsGuides

Answer 2

According to the associations you have taken,

user already have as association with the company through the Company User model, so user may have many companies according to your associations.

so,

  class User < ActiveRecord::Base

    has_many :company_users, :dependent => :destroy
    has_many :companies, :through => :company_users

  end  

current_user.companies will give you the companies.

But if you need only one company for a user then,

  class User < ActiveRecord::Base
        belongs_to :company
    end  

take belongs_to company and save company_id in users table,

then you can call,

`current_user.company`

Answer 3

According to your logic, I think you may need to create a new variable session current_company_user which is object CompanyUser. And then, to fetch company by :

current_company_user.company