Question

我目前正在使用这些模型的Rails 4.2：

class User < ActiveRecord::Base
  has_many :user_accessories, dependent: :destroy
  accepts_nested_attributes_for :user_accessories,
    reject_if: :all_blank,
    allow_destroy: true
  has_many :accessories, through: :user_accessories
end

class UserAccessory < ActiveRecord::Base
  belongs_to :user,      required: true
  belongs_to :accessory, required: true
end

class Accessory < ActiveRecord::Base
  has_many :user_accessories, dependent: :destroy
  has_many :users, through: :user_accessories
end

这是一种简单的多对多关系，用户可以自己拥有＆＃34;许多配件，配件可以拥有＆＃34;拥有＆＃34;许多用户。

我已按以下方式设置路线：

resources :users, only: [ :index, :show, :edit, :update, :accessories ] do
  member do
    get 'accessories'
  end
end

通过这种方式，用户可以使用他们的配件＆＃34;路径（/users/1/accessories）查看其附件列表，以及向其帐户添加新的附件关联。

这里是为配件路径呈现的视图：

<table>
  <thead>
    <tr>
      <th>Name</th>
    </tr>
  </thead>
  <tbody>
    <%= render @accessories %>
  </tbody>
</table>

<%= form_for( @user ) do |f| %>
  <%= f.collection_select( 
    :accessory_ids, 
    Accessory.all, 
    :id, 
    :name, { include_hidden: false }, { multiple: true } ) 
  %>

  <%= f.button "Add Equipment" %>
<% end %>

这只是呈现当前配件的表格，然后构建一个collection_select框，您可以在其中选择要添加的多个附件。我通过删除Bootstrap样式简化了这一过程。

最后，以下是相关的控制器操作：

def update
  @user = User.find( params[:id] )
  if( @user.update_attributes( update_params ) )
    redirect_to @user
  else
    render 'edit'
  end
end

def accessories 
  @user = User.find( params[:id] ) 
  @accessories = @user.accessories 
end 

private 
  def update_params 
    params.require( :user ).permit( 
      :first_name, 
      :last_name, 
      :region_id, 
      :country, 
      :profile_image, 
      :remove_profile_image, 
      accessory_ids: [:id], 
    )
  end

现在问题：

当我已经在数据库中手动输入值时，提交表单实际上只删除所有当前存储的值，并且不添加任何新值：

Started PATCH "/users/nuggles" for 127.0.0.1 at 2015-02-18 13:31:50 -0500

Processing by UsersController#update as HTML

Parameters: {
  "utf8"=>"✓",····
  "authenticity_token"=>"my_token",·
  "user"=>{
    "accessory_ids"=>["5"]
  },· 
  "button"=>"",·
  "id"=>"nuggles"
} 

User Load (40.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1  ORDER BY "users"."id" ASC LIMIT 1  [["id", 4]] 

User Load (36.4ms)  SELECT  "users".* FROM "users" WHERE "users"."slug" = $1  ORDER BY "users"."id" ASC LIMIT 1  [["slug", "nuggles"]]·

(33.5ms)  BEGIN

Accessory Load (34.1ms)  SELECT "accessories".* FROM "accessories" INNER JOIN "user_accessories" ON "accessories"."id" = "user_accessories"."accessory_id" WHERE "user_accessories"."user_id" = $1  [["user_id", 4]]

**SQL (34.1ms)  DELETE FROM "user_accessories" WHERE "user_accessories"."user_id" = $1 AND "user_accessories"."accessory_id" IN (1, 2, 3)  [["user_id", 4]]**

User Exists (37.7ms)  SELECT  1 AS one FROM "users" WHERE (LOWER("users"."username") = LOWER('Nuggles') AND "users"."id" != 4) LIMIT 1

(34.2ms)  COMMIT

Redirected to http://localhost:3000/users/nuggles
Completed 302 Found in 304ms (ActiveRecord: 250.0ms)

提交未选择任何内容的表单时，出现以下错误：

param is missing or the value is empty: user

private
  def update_params
    params.require( :user ).permit(
      :first_name,
      :last_name,
      :region_id,

Answer 1

对于任何有兴趣的人，我都有表格。这可能不是一次创建多个记录的理想方式，但它现在正在为我工作。

首先，我在accessories控制器中取出了奇怪的Users定义。由于我将直接创建，更新和销毁用户的配件，因此连接模型应该拥有自己的控制器：

class UserAccessoriesController < ApplicationController
  def index
    @user = User.friendly.find( params[:id] )
    @user_accessories = @user.user_accessories
  end

  def create
    @user = User.friendly.find( params[:id] )

    create_params[:accessory].each do |accessory|
      @user_accessory = UserAccessory.new( user: @user, accessory_id: accessory )

      @user_accessory.save
    end

    redirect_to user_accessories_path( @user )
  end

  def destroy
    @user_accessory = UserAccessory.friendly.find( params[:id] )

    @user_accessory.destroy
  end

  private
    def create_params
      params.require( :user_accessory ).permit(
        :id,
        accessory: []
      )
    end
end

我只有UserAccessories的一个视图，即索引。此页面列出了所有用户的附件，如果显示的用户与登录用户相同，则会显示以下表单：

  <%= form_for @user_accessories.new(), { method: :post } do |f| %>
    <div class="form-group">
      <%= f.collection_select(
                               :accessory,
                               # Get only accessories not on the user's account
                               Accessory.where.not( id: @user.accessories ),
                               :id,
                               :name,
                               {
                                 include_hidden: false
                               },
                               {
                                 multiple:    true,
                                 class:       'form-control',
                                 placeholder: 'Select Equipment to Add'
                               }
                             ) %>
    </div>

    <div class="form-group">
      <%= f.submit "Update Equipment" %>
    </div>
  <% end %>

这允许用户选择多个附件（使用select2），然后在提交中在控制器中逐个创建关联。

如果有人有更好的方法来创建创建用户配件（即没有循环我的参数并多次创建），那么请发表评论！

Rails 4.2 - 如何构建has_many，通过：与collection_select的关联

1 个答案: