gistfile1.rb

class Admin::SportsController < Admin::AdminController
  before_filter :validate_admin_rights
  
  admin_assistant_for Sport do |aa|
    aa.actions :index, :create, :update
    aa.index.columns :id, :name, :member_count, :groups_count, :enabled, :drills_enabled, :organizations, :player_term
    aa.index.per_page 100
    aa.index.sort_by 'name ASC'
    aa.index.include :organizations
    aa[:enabled].label = "Hub Enabled?"
    aa[:enabled].boolean_labels = %w(Yes No)
    aa[:drills_enabled].boolean_labels = %w(Yes No)
    aa[:member_count].label = "# Members"
    aa[:groups_count].label = "# Groups"
    aa.form.columns :name, :enabled, :drills_enabled, :player_term
    aa.form[:enabled].input = :check_box
    aa.form[:drills_enabled].input = :check_box
  end
  
protected

  def do_list
    super
    preload_member_and_group_counts
  end
  
  def preload_member_and_group_counts
    member_counts = id_to_count_hash_from_sql('select sports.id, count(users.id) as count from sports left outer join users on users.sport_id = sports.id group by sports.id')
    group_counts = id_to_count_hash_from_sql('select sports.id, count(groups.id) as count from sports left outer join groups on groups.sport_id = sports.id group by sports.id')

    @records.each do |sport_record|
      sport_record.member_count = member_counts[sport_record.id]
      sport_record.groups_count = group_counts[sport_record.id]
    end
  end
  
  def id_to_count_hash_from_sql(sql)
    Hash[*Sport.connection.execute(sql).all_hashes.map{|h| [h['id'].to_i, h['count'].to_i]}.flatten]
  end
end