Rails 3 Including multiple tables in one query

Question

Im working on a rails application for tournaments. I have three models im working with on this query:

class Player < ActiveRecord::Base
  validates :name, :uniqueness => true
  has_and_belongs_to_many :tournaments

class Tournament < ActiveRecord::Base
  belongs_to :tournament_type
  has_and_belongs_to_many :players
  has_many :player_matches, :dependent => :destroy

class PlayerMatch < ActiveRecord::Base
  belongs_to :player_one, :class_name => "Player", :foreign_key => "player_one"
  belongs_to :player_two, :class_name => "Player", :foreign_key => "player_two"

In the show action of the tournaments_controller, im calling the following query:

Tournament.where(:id => params[:id]).includes(:player_matches, :players).first()

While the tournaments and player_matches are done in a single join, the players are queried individually, since my code depends on them:

Player Load (0.4ms)  SELECT `players`.*, t0.tournament_id as the_parent_record_id FROM `players` INNER JOIN `players_tournaments` t0 ON `players`.id = t0.player_id WHERE (t0.tournament_id = 14)
Player Load (0.2ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 5 LIMIT 1
Player Load (0.2ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 9 LIMIT 1
Player Load (0.2ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 1 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 8 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 3 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 2 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 7 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 6 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 4 LIMIT 1

How can i change this up, so that it is all pulled in one query?

Answer 1

Tournament.where(:id => params[:id]).includes([{:player_matches => :player_one}, :players]).first()

That should do the trick. And really, the combination of array notation and hash notation is a bit messy to get sorted at first, but work with the console and you'll find out which syntax doesn't crash :)