ruby on rails - How to eager load in this case? -

class model runningtracks < activerecord::base   has_many :achievements   has_many :runners, through: :achievements  class model runner < activerecord::base   has_many :achievements   has_many :running_tracks, through: :achievements  class model achievement < activerecord::base   belongs_to :runner   belongs_to :running_tracks 

on homepage there each do list display runningtracks. next track display button mark run. eager loading solution includes , references (rails 4) in query in controller:

class runningtrackscontroller   def index     @running_tracks = runningtracks.includes(:achievements).references(:achievements)   end 

to improve usability, button next each record should not visible if had been marked. (will refactored in helper method)

@running_tracks.each |track|   .   - unless track.achievements.map(&:user_id).include? current_user.id     = button_to "done", running_track_mark_as_done_path(track) 

this works...but... database gets more records query lot of achievements, therefore custom association , includes query achievements of current_user (devise) should solution.

class model runningtracks < activerecord::base   .   has_many :achieved_runns, -> { user_id: current_user.id }, class_name "achievement" 

but because current_user not accessible in model, not work. don't think possible pass variable hay_many association, it?

is there more efficient solution eager loading of all runningtracks including only achievements current user? thank valuable time!

the following ugly , breaks activerecord metaphor, give fast lookups db grew in size. maybe else can chime in way keep within eager-loading paradigm.

class runningtrack    # returns set (for fast lookups) of track ids have @ least 1 achievement provided user    def self.running_track_ids_for_achievements_for_user(user_id)       set.new achievement.where(:user_id => user_id).pluck(:running_track_id)    end end 

then in controller:

class runningtrackscontroller    def index       @running_tracks = runningtracks.all       @running_track_ids_for_achievements_for_user = runningtrack.running_track_ids_for_achievements_for_user(current_user.id)    end end 

and view:

- unless @running_track_ids_with_achievements_for_user.include? track    = button_to "done", running_track_mark_as_done_path(track)