Multiple objects with one form and permitting parameters - ruby-on-rails

Question

My rails app has a games model, and each game has multiple players. When a game is created, a set number of players are created with a default name like so:
def create
#game = Game.new(game_params)
#game.player_number.times do
#game.players << Player.new(name: 'Santa')
end
if #game.save
redirect_to action: "players", id: #game.id
else
render 'new'
end
end
The redirect takes the user to a page that has a form with inputs for each player's name. The actions associated with this page are:
def players
#game = Game.find(params[:id])
end
def playersUpdate
#game = Game.find(params[:id])
puts player_params
if #game.players.update(player_params)
redirect_to #game
else
render 'players'
end
end
private
def player_params
params.require(players: [:name])
end
The editing page itself is:
<h2> Edit Players </h2>
<%= form_tag({:action => 'playersUpdate'},{:id => #game.id}) do %>
<%= #game.players.count %>
<% #game.players.each.with_index do |player,index| %>
<%= fields_for "players[#{index}]", player do |pl| %>
<div>
<%= pl.label :name %><br>
<%= pl.text_field :name %><br>
<%= pl.hidden_field :id %>
</div>
<% end %>
<% end %>
<div>
<%= submit_tag %>
</div>
<% end %>
Here's the routes.rb:
Rails.application.routes.draw do
get 'welcome/index'
resources :games do
collection do
match "/:id/players" => "games#players", :via => :get
match "/:id/players" => "games#playersUpdate", :via => :post
end
end
root 'welcome#index'
end
I get an error:
param is missing or the value is empty: {:players=>[:name]}
And I'm at a loss for what I could be missing. Any tips?
Here are the parameters being passed in, George is the name I'm trying to edit in, all others default to 'Santa':
Processing by GamesController#playersUpdate as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"wNwt9v2ckO/Bl8YGr/a2CDCjSsRec30E51VjZ/Qv2i5BgEnzVbH5M9DsrVfCxdLusS4Ue6Mq+aPSFOiA4K5jJg==", "players"=>{"0"=>{"name"=>"George", "id"=>"122"}, "1"=>{"name"=>"Santa", "id"=>"123"}, "2"=>{"name"=>"Santa", "id"=>"124"}, "3"=>{"name"=>"Santa", "id"=>"125"}}, "commit"=>"Save changes", "id"=>"22"}

Answer 1

You are not breaking any new ground here, and Rails has standard ways to do all of this. But it's easy to get "off the Rails" and make it harder than it needs to be.
Conceptually, stop thinking about updating a bunch of Players, and start thinking about updating a Game that happens to have some Players. The docs are surprisingly helpful here.
Let's go first to your Game model. You'll need to tell it that it's OK to update nested attributes for players, like this:
# models/game.rb
model Game < ApplicationRecord
has_many :players
accepts_nested_attributes_for :players
end
Your view is generating parameters that are not quite standard. Again, let Rails do the work for you. You don't need hidden fields or each_with_index. Since we're in Rails 5, let's use the new form_with helper, and we'll let fields_for do its job without our trying to tell it how to index:
# views/games/edit_players.html.erb
<h2> Edit Players </h2>
<%= form_with(model: game, local: true) do |form| %>
<div>
Game name: <%= form.text_field :name %>
</div>
<%= form.fields_for :players do |player_fields| %>
<div>
Player name: <%= player_fields.text_field :name %><br>
</div>
<% end %>
<div>
<%= form.submit %>
</div>
<% end %>
This will generate params that look something like this:
Parameters: {"game"=>
{"name"=>"Risk",
"players_attributes"=>
{"0"=>{"name"=>"Abel", "id"=>"1"},
"1"=>{"name"=>"Baker", "id"=>"2"},
"2"=>{"name"=>"Charlie", "id"=>"3"}}},
"commit"=>"Update Game",
"id"=>"1"}
Now you don't even need a custom update endpoint. Just use your standard GamesController#update action:
# controllers/games_controller.rb
class GamesController < ApplicationController
...
def edit_players
#game = Game.find(params[:id])
end
def update
#game = Game.find(params[:id])
if #game.update(game_params)
redirect_to #game
else
render :edit
end
end
private
def game_params
params.require(:game).permit(:name, players_attributes: [:id, :name])
end
end
Finally, your routes file is confusing because you are using collection (which doesn't expect an :id) instead of member. The routes file should look something like this:
# routes.rb
Rails.application.routes.draw do
resources :players
resources :games do
member { get :edit_players }
end
end