How to set up a typical users HABTM roles relationship

ruby-on-rails devise relational-database has-and-belongs-to-many cancan
Vasseurth picture Vasseurth · Jul 14, 2011 · Viewed 12.4k times · Source

I'm quite new to this and I'm using cancan + devise for my user auth. However I'm not really sure what it means to set up a typical users HABTM roles relationship nor do I really understand what a HABTM relationship is.

Can anyone explain it really well or point me to a good tutorial or example?

Answer

recursive picture recursive · Jul 14, 2011

HABTM means has and belongs to many. You basically need a table as a middle man to track multiple id's (called a through table). When referenced as a typical users HABTM roles relationship, they really mean there would be a User model, Role model, users table, roles table, and a roles_users table. Don't forget to add the the HABTM -- roles_users -- table. A typical setup follows:

class User < ActiveRecord::Base
  has_and_belongs_to_many :roles
end

class Role < ActiveRecord::Base
  has_and_belongs_to_many :users
end

You can then use the associations like normal saying User.first.roles and Role.first.users.

There are also a couple Railscasts on your issues.

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