Question

This code is taken from a previous question, but my question directly relates to it, so I’ve copied it here:

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

class GroupMembership < ActiveRecord::Base
  belongs_to :user
  belongs_to :role
  belongs_to :group
end

class Role < ActiveRecord::Base
  has_many :group_memberships
end

class Group < ActiveRecord::Base
  has_many :group_memberships
  has_many :users, :through > :group_memberships
end

New Question Below

How you take the above code one step further and add and work with friends?

class User < ActiveRecord::Base
  has_many :group_memberships
  has_many :groups, :through => :group_memberships
  has_many :friends # what comes here?
  has_many :actions
end

In the code above I also added actions. Let’s say that the system kept track of each user’s actions on the site. How would you code this so that each action was unique and sorted with the most recent at the top for all the user’s friends?

<% for action in @user.friends.actions %>
 <%= action.whatever %>
<% end %>

The code above may not be valid, you could do something like what I have below, but then the actions wouldn’t be sorted.

<% for friend in @user.friends %>
 <% for action in friend.actions %>
  <%= action.whatever %>
 <% end %>
<% end %>

UPDATE

I guess the real issue here is how to define friends? Do I create a new model or join table that links users to other users? Ideally, I’d like to define friends through the common group memberships of other users, but I’m not sure how to go about defining that.

has_many :friends, :through => :group_memberships, :source => :user

But that doesn’t work. Any ideas or best practice suggestions?

Answer 1

It’s been a while since I’ve worked with Rails (think Rails 1.x), but I think you can do something like the following:

Action.find(:all, :conditions => ['user_id in (?)', @user.friends.map(&:id)], :order => 'actions.date DESC')

and then in your view:

<% @actions.each do |action| %>
  <%= action.whatever -%>
<% end %>