CODEWITHSUNDEEP
ruby-on-railsassociationsrelationshiprails-activerecord
Matt Budz
Matt Budz

Reputation: 247

Add multiple records to has_and_belongs_to_many relationship

I have a HABTM relationship set up as follows:

class Game < ApplicationRecord
  has_and_belongs_to_many :players
end

and

class Player < ApplicationRecord
  validates :name, presence: true, uniqueness: true
  has_and_belongs_to_many :games
end

When a new Game is being created, I want the user to be able to select existing Players to add to the game. In the Games#new view I have:

<%= form_with(model: game) do |f| %>
  <h3>Select players participating in this game</h3>

  <% @players.each do |player| %>
    <div class="field">
      <%= check_box_tag :player_ids, player.id, false, { id: "player_#{player.id}"} %>
      <%= label_tag "player_#{player.id}", player.name %>
    </div>
  <% end %>


  <div class="actions">
    <%= f.submit 'Start Game' %>
  </div>
<% end %>

This displays each user with a checkbox to select, but when multiple players are selected and a game is created, only the last player is associated with the game.

In the controller I have

  def new
    @game = Game.new
    @players = Player.all.sort_by &:name
  end

  def create
    @game = Game.new(game_params)

    respond_to do |format|
      if @game.save
        format.html { redirect_to @game }
        format.json { render :show, status: :created, location: @game }
      else
        format.html { render :new, status: :unprocessable_entity }
        format.json { render json: @game.errors, status: :unprocessable_entity }
      end
    end
  end

  private

  def set_game
    @game = Game.find(params[:id])
  end

  def game_params
    params.permit(:player_ids)
  end

I know I should be appending player_ids but I'm not exactly sure how.

Upvotes: 0

Views: 201

Answers (1)

max
max

Reputation: 101811

Use the collection helpers in your form:

<%= form_with(model: game) do |f| %>
  <h3>Select players participating in this game</h3>

  <div class="field">
    <%= f.collection_check_boxes(:player_ids, @players, :id, :name) %>
  </div>

  <div class="actions">
    <%= f.submit 'Start Game' %>
  </div>
<% end %>

And then in your strong parameters you need to permit an array of scalar values:

class PlayersController
  def new
    @game = Game.new
    # Sort the records in the DB, not in Ruby land.
    @players = Player.all.order(:name)
  end

  def create
    @game = Game.new(game_params)
    respond_to do |format|
      if @game.save
        format.html { redirect_to @game }
        format.json { render :show, status: :created, location: @game }
      else
        format.html do
           # required to render the form
           @players = Player.all.order(:name) 
           render :new, status: :unprocessable_entity 
        end
        format.json { render json: @game.errors, status: :unprocessable_entity }
      end
    end
  end

  private

  def set_game
    @game = Game.find(params[:id])
  end

  def game_params
    params.require(:game)
          .permit(player_ids: [])
  end
end

Upvotes: 2

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