Saving model associations in the controller - ruby-on-rails

Question

I have the following models set up:
class Player < ActiveRecord::Base
has_many :game_players
has_many :games, :through => :game_players
end
class Game < ActiveRecord::Base
has_many :game_players
has_many :players, :through => :game_players
end
class GamePlayer < ActiveRecord::Base
belongs_to :game
belongs_to :player
end
Each Game has four players. I need some guidance in the controller for what saving a new game and it's 4 players in the GamePlayer model would look like. This is what I have in my controller so far:
# POST /games
# POST /games.xml
def create
#game = Game.new(params[:game])
respond_to do |format|
if #game.save
format.html { redirect_to(#game, :notice => 'Game was successfully created.') }
format.xml { render :xml => #game, :status => :created, :location => #game }
else
format.html { render :action => "new" }
format.xml { render :xml => #game.errors, :status => :unprocessable_entity }
end
end
end
Obviously it's only saving the Game model but it is unclear to me how to go about creating and saving the 4 players in GamePlayer. GamePlayer is really just supposed to have a game_id and player_id with some extra meta data for each row (like who played defense, etc.).
Any help would be appreciated.
In my view form I have the following:
<%= form_for(#game) do |f| %>
<% if #game.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#game.errors.count, "error") %> prohibited this game from being saved:</h2>
<ul>
<% #game.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :blue_score %> :
<%= f.text_field :blue_score %><br />
<%= f.label :white_score %> :
<%= f.text_field :white_score %><br />
<%= label_tag(:white_offense, "White Offense:") %>
<%= select_tag "white_offense", options_from_collection_for_select(#players, "name", "id")
<%= select_tag "white_defense", options_from_collection_for_select(#players, "name", "id")
<%= select_tag "blue_offense", options_from_collection_for_select(#players, "name", "id")
<%= select_tag "blue_defense", options_from_collection_for_select(#players, "name", "id")
<%= submit_tag("New Game") %>
</div>
<% end %>

Answer 1

Although I feel like there has to be a better way than this (perhaps using Collections?), here are is my solution:
<%= label_tag(:white_offense, "White Offense:") %>
<%= select_tag "white_offense", options_from_collection_for_select(#players, "id", "name") %>
<br />
<%= label_tag(:white_defense, "White Defense:") %>
<%= select_tag "white_defense", options_from_collection_for_select(#players, "id", "name") %>
<br />
<%= label_tag(:blue_offense, "Blue Offense:") %>
<%= select_tag "blue_offense", options_from_collection_for_select(#players, "id", "name") %>
<br />
<%= label_tag(:blue_defense, "Blue Defense:") %>
<%= select_tag "blue_defense", options_from_collection_for_select(#players, "id", "name") %>
<br />
<%= submit_tag("New Game") %>
And my controller:
#game = Game.new(params[:game])
#game.game_players.build(:player_id => params[:white_offense])
#game.game_players.build(:player_id => params[:white_defense], :is_defender => 1)
#game.game_players.build(:player_id => params[:blue_offense], :is_blue => 1)
#game.game_players.build(:player_id => params[:blue_defense], :is_blue => 1, :is_defender => 1)