Question

I was considering adding some extra properties between a has_many relationship.

For example, I have a Users table, and a Group table. Users can join groups via a :through has_many relationship. I want to add the property of the ‘role’ of the user in that group.

create_table "groupization", :force => true do |t|
    t.integer  "user_id"
    t.integer  "group_id"
    t.string  "role"
    t.datetime "created_at",                     :null => false
    t.datetime "updated_at",                     :null => false
  end

I was wondering, how can I access the role attribute. I was thinking something like:

user.groups[0].role 

Is that a correct approach? I know the syntax is wrong (I tried it); what would the correct syntax be like? Thanks!

Answer 1

In your User model, you’ll have something like:

class User < ActiveRecord::Base
  has_many :groupizations
  has_many :groups, :through => :groupizations
end

You’d access the role information just through the has_many relationship to groupizations like this in the console.

foo = User.first
bar = foo.groupizations.first
bar.role

Assuming you had groupizations on the first user.

Getting a specific user/group relationship could be done like this:

Groupizations.where("group_id = ? and user_id = ?", group.id, user.id)

Then from there you could get the role you were looking for.