使用 rails 中的嵌套 form_for 更新多对多

Question

这是一个非常普遍的问题，有数十篇博客 post 介绍了这个问题。我只是不知道我做错了什么。 很抱歉 post.

我有一个Mono-Transitive many-to-many relationship。

一个会话可以有多个字幕员。字幕员可能有多个会话。多对多关系是由"Membership"完成的。

class Session < ApplicationRecord

  # This will tell to delete all the memberships
  # in case the current session is deleted.
  has_many :memberships, dependent: :destroy
  # Added this, see:
  # https://www.sitepoint.com/master-many-to-many-associations-with-activerecord/
  has_many :captionists, through: :memberships 

  # https://www.sitepoint.com/complex-rails-forms-with-nested-attributes/
  # Allows us to delete the membersihps if not included. 
  accepts_nested_attributes_for :memberships, :allow_destroy => true

  validates :uuid, presence: true, uniqueness: true
  validates :name, presence: true, uniqueness: false
  validates :url, presence: true, uniqueness: true
  validates :passcode, presence: true, uniqueness: true
  validates :shortcode, presence: true, uniqueness: true

end

class Captionist < ApplicationRecord

  has_many :memberships

  # Added this, see:
  # https://www.sitepoint.com/master-many-to-many-associations-with-activerecord/
  has_many :sessions, through: :memberships

  validates :uuid, presence: true, uniqueness: true
  validates :full_name, presence: true, uniqueness: false
  validates :access_token, presence: true, uniqueness: true
  validates :passcode, presence: true, uniqueness: false

end

# Mono Transitive Association
# https://www.sitepoint.com/master-many-to-many-associations-with-activerecord/

class Membership < ApplicationRecord

  belongs_to :session
  belongs_to :captionist

  validates :uuid, presence: true, uniqueness: true
  validates :hostname, presence: true, uniqueness: false
  validates :web_port, presence: true, uniqueness: false
  validates :tcp_port, presence: true, uniqueness: false

end

这是我的 session_controller（在管理命名空间下）

module Admin
  class SessionsController < Admin::BaseAdminController
    def index
      # List of sessions
      # Careful on not to iterate through everything, as Rails will interpret it 
      # as all. 
      # Default is #25
      # This uses the kaminari gem. 
      # https://github.com/kaminari/kaminari
      @sessions = Session.page(params[:page] || 1)
      @page_count = @sessions.total_pages
    end

    def edit
      @session = Session.includes(:memberships).includes(:captionists).find(params[:id])
      if !@session 
        raise ActionController::RoutingError.new('Not Found')
      end
    end

    def update
      @session = Session.find(params[:id])
      if @session.update_attributes(session_params)
        respond_to do |format|
          format.html { redirect_to edit_admin_session_path , notice: 'Session was successfully updated.' }        
        end
        return
      end
      render 'edit'
    end

    def session_params
      return params.require(:session).permit(:name, :passcode, :shortcode, 
       membership_attributes: [:id, :hostname, :tag_teaming, :web_port, :tcp_port, :allowing_connections, :_destroy])
    end

  end
end

最后但同样重要的是 .erb 文件：

 <h1>Editting!!</h1>

<%= link_to 'Go Back To list', admin_sessions_path %>

<%= form_for :session, method: :patch,  class:'container' do |f| %>
  <div class="form-group">
    <%= f.label :name %>
    <%= f.text_field :name, class: 'form-control' %><br />
  </div>

  <div class="form-group">
    <%= f.label :passcode %>
    <%= f.text_field :passcode, class: 'form-control' %><br />
  </div>


  <%= f.label :shortcode %>
  <%= f.text_field :shortcode, class: 'form-control' %><br />


  <%= f.label :memberships %>
  <table class="table table-striped table-hover">
  <thead class="thead-dark">
    <tr>
    <th scope="col"> Allowing Connections </th>
    <th scope="col">Tag Teaming</th>
    <th scope="col">Hostname</th>
    <th scope="col">Web Port</th>
    <th scope="col">TCP Port</th>
    <th scope="col">Captionist Name </th>
    <th scope="col">Action</th>
    </tr>
  </thead>

<!-- HERE'S THE PART THAT is giving me the problem -->
          <% @session.memberships.map do |membership| %>

      <%= f.fields_for membership do |ff| %>
        <tr class="nested-fields">
          <%= ff.hidden_field :id %>
          <td>
          <%= ff.label :allowing_connections %>
          <%= ff.check_box :allowing_connections %>
          </td>
          <td>
          <%= ff.label :tag_teaming %>
          <%= ff.check_box :tag_teaming %>
          </td>
          <td>
          <%= ff.label :hostname %>
          <%= ff.text_field :hostname %>
          </td>
          <td>
          <%= ff.label :web_port %>
          <%= ff.text_field :web_port %>
          </td>
          <td>
          <%= ff.label :tcp_port %>
          <%= ff.text_field :tcp_port %>
          </td>
          <td>
          <%= membership.captionist.full_name %>

          </td>
          <td>
            <%= ff.check_box :_destroy %>

          </td>
        </tr>
        <% end %>
      <% end %>
  </table>
  <%= f.submit 'Update', class: 'btn btn-primary' %>
<% end %>

发送的参数如下：

 {"name"=>"Session Correct name", "passcode"=>"A Passcode", "shortcode"=>"A Shortcode", "membership"=>{"id"=>"106", "allowing_connections"=>"0", "tag_teaming"=>"0", "hostname"=>"delete hostname", "web_port"=>"80", "tcp_port"=>"3001", "_destroy"=>"0"}} permitted: false>

以下是我将参数列入白名单的方式：

return params.require(:session).permit(:name, :passcode, :shortcode, 
       membership_attributes: [:id, :hostname, :tag_teaming, :web_port, :tcp_port, :allowing_connections, :_destroy])

有什么问题？

1) 现在，如果我提交表单，我会在控制台末尾得到：unpermitted_params=["membership"] 2) 我检查过数据库是否已正确迁移。外键设置正确。我可以毫无问题地浏览属性。我所做的是在执行迁移后添加关系 has_many。我不知道我是否需要添加某种迁移才能使更新正常工作。 3) 我试过替换

<%= form_for :session, method: :patch,  class:'container' do |f| %>

对于： <%= form_for @session, 方法: :patch, class:'container' do |f| %>

但是我收到一个错误：

Could not find a valid mapping for #

4) 我也尝试删除 <% @session.memberships.map do |membership| %>，但我不会填充这些字段。我看到的另一个问题是输入的名称都相同。每当我发送要更新的参数时，它只会反映嵌套部分的最后一部分。

这是服务器的响应（params[:session]）：

Parameters {"name"=>"Session Correct name", "passcode"=>"A Passcode", "shortcode"=>"A Shortcode", "membership"=>{"id"=>"106", "allowing_connections"=>"0", "tag_teaming"=>"0", "hostname"=>"delete hostname", "web_port"=>"80", "tcp_port"=>"3001", "_destroy"=>"0"}} permitted: false>

这是一个视觉效果示例：

未嵌套的部分得到更新。

有什么想法吗？

谢谢！

编辑（2018 年 4 月 9 日）：添加了发送的参数（我这里没有）。修复了格式和 HTML.

的问题

Answer 1

我很确定这只是一个复数问题。我正在研究与您的代码类似的代码，看起来您想要 memberships_attributes 在您的强参数中。

还要检查正在生成的 HTML，并确保您允许的密钥匹配。

我建议在控制器中放置一个 binding.pry 或任何你喜欢调试的东西，然后尝试用传入的参数保存对象。

Answer 2

你不需要：

<% @session.memberships.map do |membership| %>

  <%= f.fields_for membership do |ff| %>

您只需要：

<%= f.fields_for @session.memberships do |ff| %>

Rails 将遍历会话中的所有成员并将所有字段放入 memberships_attributes.

使用 rails 中的嵌套 form_for 更新多对多

Updating many to many using a Nested form_for in rails

activerecord

ruby-on-rails

erb

nested-forms

form-for