Question

数据库中有三个表：

用户（非空）
时间表（非空）
schedules_users（ empty ）

用户模型：

class User < ActiveRecord::Base
  [...]
  has_and_belongs_to_many :schedules#has_many :schedules
  [...]
end

的时间表模型：

class Schedule < ActiveRecord::Base
  has_and_belongs_to_many :users#belongs_to :user
end

welcome-controller：（我希望按日期和时间对日程安排进行排序）

class WelcomeController < ApplicationController
  def index
    if(current_user)
      @user_schedules = current_user.schedules
      @user_schedules_date = @user_schedules.order(:date_time).group_by { |sched| sched.date_time.beginning_of_day }
    end
  end
end

@user_schedules = current_user.schedules这不正确，不是吗？
的 SQL-输出：

Started GET "/" for 127.0.0.1 at 2014-07-30 11:24:09 +0200
Processing by WelcomeController#index as HTML
  User Load (1.0ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 12 LIMIT 1
  Schedule Load (1.0ms)  SELECT "schedules".* FROM "schedules" INNER JOIN "schedules_users" ON "schedules"."id" = "schedules_users"."schedule_id" WHERE "schedules_users"."user_id" = $1 ORDER BY "schedules"."date_time" ASC  [["user_id", 12]]
  Rendered welcome/index.html.erb within layouts/application (0.0ms)
Completed 200 OK in 47ms (Views: 43.0ms | ActiveRecord: 2.0ms)

的欢迎视图：

<div class="table-responsive">
  <table class="table table-hover">
    <tbody>
      <% @user_schedules_date.sort.each do |date_time, schedules| %>
        <tr class="thead success">
          <th colspan="4" scope="col"><p><%= date_time.strftime("%A, %d.%m.%Y") %></p></th>
        </tr>
        <% for schedule in schedules %>
          <tr>
            <th scope="row"><p><%= schedule.titel %></p></th>
            <td><p><%= schedule.date_time.strftime("%H:%M:%S") %></p></td>
            <td><p><%= schedule.location %></p></td>
          </tr>
        <% end %>
      <% end %>
    </tbody>
  </table>
</div>

查看/ HTML输出：

<div class="table-responsive">
  <table class="table table-hover">
    <tbody>
    </tbody>
  </table>
</div>

数据库：（schedules_users）
enter image description here

说明
如你所见，我改变了has_many＆amp;的关系。 belongs_to至has_and_belongs_to_many。
没有错误或例外一切都应该是正确的（我不知道欢迎控制器中的排序命令是否正确）。
SQL输出看起来也是正确的
如何将数据添加到schedules_users-table？
和
如何访问schedules_users-table中添加的数据？
我需要一个名为ScheduleUsers的新模型，还是......？我不理解它。
如果有人能帮助我会很好。
感谢。

编辑:(解决方案[Rich Peck]）

时间表控制器：

# encoding: UTF-8
class ScheduleController < ApplicationController
  def add
    if (current_user.nil?)
      redirect_to "/"
    else
      if (@schedule_add.nil?)
        @schedule_add = Schedule.new
      end
    end
  end

  def add_now
    @schedule_add = Schedule.new(schedule_params)
    if @schedule_add.valid?

      @schedule_add.save

      current_user.schedules << @schedule_add # ADD RELATIONSHIP TO THE JOIN-TABLE

      #UserMailer.welcome_email(@user).deliver #BestätigungsEmail versenden
      flash[:notice] = 'Ein neuer Termin wurde erstellt.'
      redirect_to :root
    else
      render :action => "add"
    end
  end

  def edit
    if (current_user.nil?)
      redirect_to "/"
    else
      if current_user.schedules.nil?
        redirect_to "/"
      else
        begin #try
        @schedule_edit = current_user.schedules.find(params[:id])
        rescue #catch
          if @schedule_edit.nil?
            flash[:notice] = 'Der Termin konnte nicht gefunden werden.'
            redirect_to :root
          end
        end
      end
    end
  end

  def edit_now
    @schedule_edit = current_user.schedules.find(params[:id])
    if @schedule_edit.nil?
      flash[:notice] = 'Der Termin konnte nicht gefunden werden.'
      redirect_to :root
    else
      @schedule_edit.update(schedule_params)
      if @schedule_edit.valid?

        @schedule_edit.save

        flash[:notice] = 'Der Termin '+@schedule_edit.titel+' wurde bearbeitet.'
        redirect_to :root
      else
        render :action => "edit"
      end
    end
  end

  def delete
    if (current_user.nil?)
      redirect_to "/"
    else
      if current_user.schedules.nil?
        redirect_to "/"
      else
        begin #try
          @schedule_delete = current_user.schedules.find(params[:id])
        rescue #catch
          if @schedule_delete.nil?
            flash[:notice] = 'Der Termin konnte nicht gefunden werden.'
            redirect_to :root
          end
        end
      end
    end
  end

  def delete_now
    begin #try
      @schedule_delete = current_user.schedules.find(params[:id])
    rescue #catch
      if @schedule_delete.nil?
        flash[:notice] = 'Der Termin konnte nicht gefunden werden.'
        redirect_to :root
      end
    end

    if @schedule_delete.nil?
      flash[:notice] = 'Der Termin konnte nicht gefunden werden.'
      redirect_to :root
    else
      @schedule_delete.delete #SHOULD DELETE RELATIONSHIP IN THE JOIN-TABLE, BUT DIDNT
      flash[:notice] = 'Der Termin '+@schedule_delete.titel+' wurde gelöscht.'
      redirect_to :root
    end
  end

  def invite
  end
  # ---------------------------------------------------------------------------
  private
  #allowed parameters to pass through to the model
  def schedule_params
    params.require(:schedule).permit(:id, :titel, :location, :date_time)
  end
end

的 routes.rb中：

Calendar::Application.routes.draw do
  root 'welcome#index'

  get "welcome/index" => "welcome#index"

  get "auth/sign_up" => "auth#sign_up"
  get "auth/sign_in" => "auth#sign_in"
  get "auth/sign_out" => "auth#sign_out"
  get "auth/settings" => "auth#settings"
  get "auth/pwd_forgot" => "auth#pwd_forgot"
  get "auth/pwd_reset" => "auth#pwd_reset"

  post "auth/sign_in" => "auth#login"
  post "auth/sign_up" => "auth#register"
  put "auth/settings" => "auth#save_settings"
  put "auth/pwd_forgot" => "auth#send_pwd_reset_instructions"
  put "auth/pwd_reset" => "auth#new_pwd"

  delete "auth/settings" => "auth#delete"

  #resources :users, only: :index
  #resources :users do
  #  post   :add, action: :add_schedule #-> domain.com/users/4/schedules/add
  #  delete :remove, action: :remove_schedule #-> domain.com/users/4/schedules/remove
  #end

  get "schedule/add" => "schedule#add"
  post "schedule/add" => "schedule#add_now"
  get "schedule/invite" => "schedule#invite"
  #get "schedule/edit" => "schedule#edit"
  #get "schedule/edit/:id" => "schedule#edit"
  get '/schedule/edit/:id', to: 'schedule#edit', as: 'schedule/edit'
  put "schedule/edit/:id" => "schedule#edit_now" #PUT oder POST ?
  #get "schedule/delete" => "schedule#delete"
  get '/schedule/delete/:id', to: 'schedule#delete', as: 'schedule/delete'
  delete "schedule/delete/:id" => "schedule#delete_now"
end

的欢迎视图：

<div class="table-responsive">
      <table class="table table-hover">
        <tbody>
          <% @user_schedules_date.sort.each do |date_time, schedules| %>
            <!-- Datum -->
            <tr class="thead success">
              <th colspan="4" scope="col"><p><%= date_time.strftime("%A, %d.%m.%Y") %></p></th>
            </tr>
            <!-- /Datum_Ende -->

            <!-- Titel, Zeit und Ort -->
            <% for schedule in schedules %>
              <tr>
                <th scope="row"><p><%= schedule.titel %></p></th>
                <td><p><%= schedule.date_time.strftime("%H:%M:%S") %></p></td>
                <td><p><%= schedule.location %></p></td>
                <td>
                  <p><%= link_to 'Bearbeiten', {:controller => 'schedule', :action => 'edit', :id => schedule.id} %></p>
                  <p><%= link_to 'Diesen Termin löschen', {:controller => 'schedule', :action => 'delete', :id => schedule.id} %></p>
                </td>
              </tr>
            <% end %>
            <!-- Titel, Zeit und Ort -->
          <% end %>
        </tbody>
      </table>
    </div>
  <% end %>

如果我添加一个计划，一切正常。编辑也很好。
如果我删除了一个计划，它将不会删除Join-Table中的关系 任何想法为什么？ - ＆gt;解决方案：@schedule_delete.DESTROY而不是@schedule_delete.delete。因此，删除/销毁时间表也可以正常工作
所以一切正常。
感谢您的帮助！

Answer 1

让我为您解释has_and_belongs_to_many

HABTM 基本上是ActiveRecord为您提供join table的一种方式 - 您的关联使您能够加载所需的关联数据通过您的加入表

与has_many :through非常相似，HABTM提供了一种访问模型关联数据的简单方法，但由于它没有模型，因此无法直接访问连接数据（因为没有primary key加载它们）：

enter image description here

它基本上使用了连接表的foreign_keys，并允许您从任一依赖模型中提取相关数据。你不能设置

如何将数据添加到schedules_users-table？

您必须使用collection ActiveRecord methods，特别是您必须确保能够将记录追加到schedules或users协会：

#config/routes.rb
resources :users do
    post   :add, action: :add_schedule #-> domain.com/users/4/schedules/add
    delete :remove, action: :remove_schedule #-> domain.com/users/4/schedules/remove
end

#app/controllers/users_controller.rb
Class UsersController < ApplicationController
    before_action :set_schedule, only: [:add_schedule, :remove_schedule]
    def add_schedule
       @user.schedules << @schedule #-> has to be an ActiveRecord object
    end

    def remove_schedule
       @user.schedules.delete params[:schedule_id]
    end

    private

    def set_schedule
       @user = User.find params[:user_id]
       @schedule = Schedule.find params[:id]
    end
end

-

如何访问schedules_users-table中添加的数据？

您只能通过集合关联访问此数据：

$ rails c $ @user = User.find 1 $ @user.schedules.each do |schedule| $ puts schedule #-> will output each schedule record $ end

要从您的控制器访问，您将运行完全相同的命令

Answer 2

看起来很快，但对我来说看起来很不错。但是，由于您已将模型从has_many更改为has_and_belongs_to_many，因此如果希望显示旧数据，则需要迁移数据。现在您没有为您的用户提供任何计划，这是正确的，因为schedules_users表为空。假设您的日程表中仍然有user_id列，您可以执行类似迁移数据的操作：

insert into schedules_users 
(select id as schedule_id, user_id from schedules where user_id is not null);

需要帮助来理解`has_and_belongs_to_many`

2 个答案: