CODEWITHSUNDEEP
ruby-on-railsrubyruby-on-rails-3
blogosfaira
blogosfaira

Reputation: 31

Has and belongs to many with 3 Models

What if I had 3 Models that I wanted to connect.

For example:

A user can have many different permissions for many different applications.

So I need a table to store:

user_id
permission_id
application_id

Is that possible with has_and_belongs_to_many?

Thanks

Upvotes: 3

Views: 1106

Answers (2)

Branden Tanga
Branden Tanga

Reputation: 174

I would do it with a has_many :through.

class Upa < ActiveRecord::Base
  belongs_to :user 
  belongs_to :permission 
  belongs_to :application
end
class User < ActiveRecord::Base
  has_many :permissions, :through => :upas
  has_many :applications, :through => :upas
end
class Permission < ActiveRecord::Base
  has_many :users, :through => :upas
  has_many :applications, :through => :upas
end
class Application < ActiveRecord::Base
  has_many :permissions, :through => :upas
  has_many :users, :through => :upas
end

examples of has_many :through

Basically any sort of relationship that you can describe with a classical one to one, one to many and many to many relationships in relational databases can be described in ActiveRecord.

Upvotes: 4

Matthew Burket
Matthew Burket

Reputation: 316

Yes, you can have has_and_belongs_to_many relationship. More help can be found here http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html

Upvotes: 0

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