Rails has_many：通过，茧

Question

播放器.rb

class Player < ApplicationRecord
belongs_to :user
has_many :player_games, dependent: :destroy, inverse_of: :player
has_many :games, :through => :player_games

validates :firstname, presence: true, length: { minimum: 3, maximum: 88 }
validates :lastname, presence: true, length: { minimum: 3, maximum: 88 }
validates :user_id, presence: true

accepts_nested_attributes_for :player_games, reject_if: :reject_posts, allow_destroy: true

def reject_posts(attributes)
    attributes['game_id'].to_i == 0
    attributes['score'].blank?
    attributes['time'].blank?
end

def initialized_player_games # this is the key method
    [].tap do |o|
        Game.all.each do |game|
            if g = player_games.find { |g| g.game_id == game.id }
                o << g.tap { |g| g.enable ||= true }
            else
                o << PlayerGame.new(game: game)
            end
        end
    end
end
end

players_controller.rb

class PlayersController < ApplicationController
before_action :set_player, only: [:edit, :update, :show, :destroy]
before_action :require_user, except: [:index, :show]
before_action :require_same_user, only: [:edit, :update, :destroy]

before_filter :process_player_games_attrs, only: [:create, :update]

def process_player_games_attrs
  params[:player][:player_games_attributes].values.each do |game_attr|
    game_attr[:_destroy] = true if game_attr[:enable] != '1'
  end
end

.......

private
  # Use callbacks to share common setup or constraints between actions.
  def set_player
    @player = Player.find(params[:id])
  end

  # Never trust parameters from the scary internet, only allow the white list through.
  def player_params
    params.require(:player).permit(:id, :firstname, :lastname, player_games_attributes: [:id, :game_id, :score, :time, :enable, :_destroy] )
  end

  def require_same_user
    if current_user != @player.user and !current_user.admin?
      flash[:danger] = "You can edit or delete only your own player"
      redirect_to root_path
    end 
  end

end

_form of 'PLAYER'

<%= form_for(@player, :html => {class: "az-form", role: "form"}) do |player_form| %>

  <%= player_form.label :firstname, class: "az-form__label" %> <br/>
  <%= player_form.text_field :firstname, class: "az-form__input", placeholder: "Firstname of player", autofocus: true %>

  <%= player_form.label :lastname, class: "az-form__label" %> </br>
  <%= player_form.text_field :lastname, class: "az-form__input", placeholder: "Lastname of player" %>

  <%= player_form.fields_for :player_games, @player.initialized_player_games do |builder| %>

    <% @game = builder.object.game %>

    <%= render 'result_fields', f: builder %>

    <div class="links">
      <%= link_to_add_association 'add result', player_form, :player_games, :partial => 'players/result_fields' %>
    </div>

    <hr>

  <% end %>

  <div class="text-center">
    <%= button_tag(type: "submit", class: "az-form__submit") do %>
        <%= player_form.object.new_record? ? "Create player" : "Update player" %>
    <% end %>
  </div>

<% end %>

_result_fields.html.erb

<div class="nested-fields">

<%= f.hidden_field :game_id, :value => @game.id%>

<div class="row">
  <div class="col-md-12">
    <label class="az-form__label az-form__label--unable js-az-form__checkbox" data-check="<%= @game.id %>">
      <%= f.check_box :enable %>
      <%= @game.title %>
     </label>
  </div>
 </div>

<div class="row">
  <div class="col-md-6">
    <%= f.label :score,
                    class: "az-form__label", :data => {:check => @game.id } %> </br>
     <%= f.number_field :score, step: :any, :data => {:check => @game.id },
                           class: "az-form__input az-form__input--disabled",
                           placeholder: "Score for '#{@game.title}'", disabled: true %>
      </div>
      <div class="col-md-6">
     <%= f.label :time,
                    class: "az-form__label", :data => {:check => @game.id } %> </br>
  <%= f.number_field :time, step: :any, :data => {:check => @game.id },
                           class: "az-form__input az-form__input--disabled",
                           placeholder: "Time for '#{@game.title}'", disabled: true %>
   </div>
 </div>

 <div class="row">
  <div class="col-md-12">
   <%= link_to_remove_association "remove result", f %>
    </div>
  </div>

</div>

问题：

当编辑“玩家”时，每个游戏只能访问一个结果，不能更改其他结果，与“initialized_player_games”方法冲突，但如果我从表单中删除此方法效果很好，但如果不创建新游戏则无法创建另一个游戏操作，我该如何正确更改此方法？

Answer 1

如果我理解正确，您想为所有游戏添加一个条目（有效），但添加一个新的Result 不会。问题是@game 可能未定义或设置为最后一场比赛。

我也不太喜欢这种方法（给fields_for 一个特定的集合）。相反，我会稍微调整这种方法。我不会使用initialized_player_games，而是使用一种方法，在控制器中调用，例如add_default_player_games，类似

def add_default_player_games 
  Game.all.each do |game|
    if g = player_games.find { |g| g.game_id == game.id }
      g.enable ||= true 
    else
      player_games.build(game: game)
    end
  end
end

有效地将新实例添加到集合中，而不保存它们。

所以在你的控制器中你会写

 @player = Player.new
 @player.add_default_player_games

或edit

 @player = Player.find(params[:id])
 @player.add_default_player_games

然后您的视图将遍历 player_games

<%= player_form.fields_for :player_games do |builder| %>
  <%= render 'result_fields', f: builder %>
<% end %>

然后，如果您使用simple-form，那么如果尚未选择游戏，那么选择游戏将非常容易，并且不需要丑陋的@game。

所以在 _result_fields 中做类似的事情（在 haml 中，因为我是一个懒惰的打字员）

.nested-fields
  - game_id = f.object.game_id 
  - if game_id.present? 
    = f.hidden_field :game_id
  - else 
    = f.collection_select :game_id, Game.all, :id, :name
  ...

简而言之：如果有game_id，则不允许更改它（显示游戏标题或其他内容会很有用），但如果没有，请使用下拉选择来选择游戏。 其余部分保持不变（仅使用game_id 而不是@game.id）。