Question

I am working on a Rails 2.3.9 app and my question involves both a self referencial relationship and a named_scope. This application allows users to log and share workouts. A workout can be public or private and that is designated by @workout.public == 1.

I allow users to ‘follow’ people. So on a current_user’s dashboard I display all public workouts from users that current_user follows with the following code:

/dashboard/index.html.erb

 <% current_user.friends_workouts.each do |workout| %>
  <%= link_to (workout.title), workout %> <br/>
  by <%= link_to (workout.user.username), workout.user %> - <%= time_ago_in_words(workout.created_at)%> ago</p>
 <% end %>

user.rb

def friends_workouts
 @friends_workouts ||= Workout.current.public_workouts.find_all_by_user_id(self.friends.map(&:id), :order =>  "created_at DESC", :limit => 3)
end

workout.rb

named_scope :public_workouts, :conditions => {:public => 1 }, :order => "created_at DESC"

I now want to add a condition to this scope as I am adding another level of sharing. Users can associate to a “box” (a gym really) through a “membership” model. So if the current_user belongs_to the same “box” as a user they follow, they should not only see the workouts marked public but also workouts where @workout.box_only == 1.

How can I affect the above to include all public workouts from followed users AND workouts from followed users where @workout.box_only == 1 and @workout.user.membership.box_id == current_user.membership.box_id. I know that syntax is incorrect but you get my point (hopefully).

UPDATE:

It also needs to be considered that :public_workouts is being called from pages that don’t require a logged_in? user so in that case if the scope is trying to reference current_user it will throw an error.

UPDATE 2:
:user has_many :memberships

Answer 1

I believe something like the following should do it for you:

named_scope :public_workouts, 
            :joins => ", user, membership"
            :conditions => 
              "workouts.public = 1 or
               membership.box_id = #{current_user.membership.box_id}",
            :group => "workouts.id",
            :order => "workouts.created_at DESC"

You would have to play around with this for a bit. The hard part every time I try something like this is to get the OR conditions correct. You want to get all public and those where the joined membership.box_id matches regardless of public being 1.

Edit: Admittedly this is perhaps not the most ruby way of building a query and I haven’t tested it properly but something like below could also be made to work.

def self.public_workouts
  query = Workout.joins(:user => { :membership })
  if current_user
    query.where('memberships.box_id = ? or workouts.public = 1', current_user.membership.box_id) unless current_user.membership.box_id.nil?
  else
    query.where('workouts.public = 1')
  end
  query.group('workouts.id')
  query.order("workouts.created_at DESC")
  return query
end

Edit2
Another alternative could be to create two separate scopes and create a class method that combines the two scopes. This class method would then be used in the view.

named_scope :box_workouts, 
            :joins => ", user, membership"
            :conditions => "memberships.box_id = #{current_user.membership.box_id}"
            :group => "workouts.id",
            :order => "workouts.created_at DESC",
            :select "workouts"

named_scope :public_workouts, 
            :conditions => :public => 1
            :order => "workouts.created_at DESC"    

def self.public_box_workouts
  return box_workouts.merge(public_workouts).limit(3) if current_user
  return public_workouts.limit(3)
end     

Edit3 Not so hard, I believe something like below will work.

def self.box_and_public_workouts(user)
  return public_workouts if user.nil? or user.memberships.blank?
  return public_workouts + box_workouts(user.memberships.map(&:box_id))
end

named_scope :box_workouts, lambda { |box_ids| { :conditions => ['box_id IN (?)', box_ids], :order => 'created_at DESC' } }

Apologies for taking so long. I was missing confused with how the “old” way of querying the database. I went right for Rails3 🙂

Anyway, I didn’t want to commit anything so I tried to fork it to send a pull request but github is being rude to me tonight. Might just copy from here then.