ruby-on-rails - Rails 4 : undefined method `relation_delegate_class' for Model:Class

我正在尝试遵循有关Creating a Scoped Invitation System for Rails的coderwall教程。

在我的Rails 4应用程序中，我具有以下模型:

class User < ActiveRecord::Base
  has_many :administrations
  has_many :calendars, through: :administrations
  has_many :invitations, :class_name => "Invite", :foreign_key => 'recipient_id'
  has_many :sent_invites, :class_name => "Invite", :foreign_key => 'sender_id'
end

class Calendar < ActiveRecord::Base
  has_many :administrations
  has_many :users, through: :administrations
  has_many :invites
end

class Administration < ActiveRecord::Base
  belongs_to :user
  belongs_to :calendar
end

class Invite < ActiveRecord::Base
  belongs_to :calendar
  belongs_to :sender, :class_name => 'User'
  belongs_to :recipient, :class_name => 'User'
end

这是我的模型与本教程中的模型之间的对应关系:

User User

Calendar UserGroup

Administration Membership

Invite Invite

我现在位于“发出新邀请”部分:

已使用Invite过滤器和before_create方法更新了generate_token模型。

已使用Invites操作更新了create Controller 。

但是，当我访问“日历”编辑 View 以填写“邀请”表单时，出现以下错误:

NoMethodError in CalendarsController#edit
undefined method `relation_delegate_class' for Invite:Class
def edit
  @user = current_user
  @invite = @calendar.invites.build
  authorize @calendar
end

问题似乎来自@invite = @calendar.invites.build行。

——————

更新:这是我的邀请模型的内容:

class Invite < ActiveRecord::Base
  belongs_to :calendar
  belongs_to :sender, :class_name => 'User'
  belongs_to :recipient, :class_name => 'User'

  before_create :generate_token

  def generate_token
   self.token = Digest::SHA1.hexdigest([self.calendar_id, self.recipient_role, Time.now, rand].join)
  end

end

——————

更新2 :在this question中，作者解释了该问题可能来自CanCanCan＆Rolify。我不使用这些 gem ，但是我使用Pundit。认为这对我的问题很有用。

——————

更新3 :这也是我用于Invite模型的迁移:

class CreateInvites < ActiveRecord::Migration
  def change
    create_table :invites do |t|
      t.string :email
      t.integer :calendar_id
      t.integer :sender_id
      t.integer :recipient_id
      t.string :recipient_role
      t.string :token
      t.timestamps null: false
    end
  end
end

我想知道问题是否可能由t.string :recipient_role引起，因为对于给定的role，给定user的administration仅存在于calendar表中:如果rails自动将:recipient_role解释为recipient.role，那么这可能是导致错误的原因吗？

——————

更新4 :这是CalendarsController的内容:

class CalendarsController < ApplicationController
  before_action :set_calendar, only: [:show, :edit, :update, :destroy]
  before_action :authenticate_user!

  # GET /calendars
  # GET /calendars.json
  def index
    @user = current_user
    @calendars = @user.calendars.all
  end

  # GET /calendars/1
  # GET /calendars/1.json
  def show
    @user = current_user
    @calendar = @user.calendars.find(params[:id])
    authorize @calendar
  end

  # GET /calendars/new
  def new
    @user = current_user
    @calendar = @user.calendars.new
    authorize @calendar
  end

  # GET /calendars/1/edit
  def edit
    @user = current_user
    @invite = @calendar.invites.build
    authorize @calendar
  end

  # POST /calendars
  # POST /calendars.json
def create
  @user = current_user
  @calendar = @user.calendars.create(calendar_params)
  authorize @calendar
  respond_to do |format|
    if @calendar.save
      current_user.set_default_role(@calendar.id, 'Owner')
      format.html { redirect_to calendar_path(@calendar), notice: 'Calendar was successfully created.' }
      format.json { render :show, status: :created, location: @calendar }
    else
      format.html { render :new }
      format.json { render json: @calendar.errors, status: :unprocessable_entity }
    end
  end
end

  # PATCH/PUT /calendars/1
  # PATCH/PUT /calendars/1.json
  def update
    @user = current_user
    @calendar = Calendar.find(params[:id])
    authorize @calendar
    respond_to do |format|
      if @calendar.update(calendar_params)
        format.html { redirect_to calendar_path(@calendar), notice: 'Calendar was successfully updated.' }
        format.json { render :show, status: :ok, location: @calendar }
      else
        format.html { render :edit }
        format.json { render json: @calendar.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /calendars/1
  # DELETE /calendars/1.json
  def destroy
    @user = current_user
    @calendar.destroy
    authorize @calendar
    respond_to do |format|
      format.html { redirect_to calendars_url, notice: 'Calendar was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

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

    # Never trust parameters from the scary internet, only allow the white list through.
    def calendar_params
      params.require(:calendar).permit(:name)
    end
end

——————

更新5 :这是服务器日志:

Started GET "/calendars/2/edit" for ::1 at 2015-09-14 11:44:13 -0700
Processing by CalendarsController#edit as HTML
  Parameters: {"id"=>"2"}
  Calendar Load (0.1ms)  SELECT  "calendars".* FROM "calendars" WHERE "calendars"."id" = ? LIMIT 1  [["id", 2]]
  User Load (0.2ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ?  ORDER BY "users"."id" ASC LIMIT 1  [["id", 1]]
Completed 500 Internal Server Error in 3ms (ActiveRecord: 0.3ms)

NoMethodError (undefined method `relation_delegate_class' for Invite:Class):
  app/controllers/calendars_controller.rb:30:in `edit'


  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1@global/gems/actionpack-4.2.2/lib/action_dispatch/middleware/templates/rescues/_source.erb (6.0ms)
  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1@global/gems/actionpack-4.2.2/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb (2.8ms)
  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1@global/gems/actionpack-4.2.2/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (1.7ms)
  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1@global/gems/actionpack-4.2.2/lib/action_dispatch/middleware/templates/rescues/diagnostics.html.erb within rescues/layout (68.9ms)
  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1/gems/web-console-2.2.1/lib/web_console/templates/_markup.html.erb (0.5ms)
  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1/gems/web-console-2.2.1/lib/web_console/templates/_inner_console_markup.html.erb within layouts/inlined_string (0.3ms)
  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1/gems/web-console-2.2.1/lib/web_console/templates/_prompt_box_markup.html.erb within layouts/inlined_string (0.3ms)
  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1/gems/web-console-2.2.1/lib/web_console/templates/style.css.erb within layouts/inlined_string (0.3ms)
  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1/gems/web-console-2.2.1/lib/web_console/templates/console.js.erb within layouts/javascript (39.3ms)
  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1/gems/web-console-2.2.1/lib/web_console/templates/main.js.erb within layouts/javascript (0.4ms)
  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1/gems/web-console-2.2.1/lib/web_console/templates/error_page.js.erb within layouts/javascript (0.4ms)
  Rendered /Users/TXC/.rvm/gems/ruby-2.2.1/gems/web-console-2.2.1/lib/web_console/templates/index.html.erb (94.2ms)

——————

更新6 :我只是意识到自己没有

def invite_params
  params.require(:invite)
end

在Invites Controller 中:这可能是问题的根源吗？

——————

是否知道此错误消息的含义以及如何解决此问题？

最佳答案

很难特别是仅从问题内容中识别问题。

问题

我收到undefined method 'relation_delegate_class' for Invite:Class错误的原因是，Rails不再将Invite视为模型。

问题的根本原因

创建Invite邮件程序时，我运行rails g mailer Invite而不是rails g mailer InviteMailer。

因此，作为邮件程序的Invite会替代Invite作为模型，因此，一旦将方法应用于Invite模型的实例，就会产生错误。

我们如何计算出

我的一位比我更富有编程经验的 friend 通过调整导致错误的@invite = @calendar.invites.build行识别了问题。

这最终导致我们最终在rails控制台中运行Invite.first:尽管我们应该获得Invite类的实例或nil，但实际上却出现了错误。

由于.first应该是任何ActiveRecord模型上的有效方法，因此我们意识到rails并不将Invite视为模型。

我们如何修复

一旦我们确定了问题，就可以很容易地解决它:

我们将Invite邮件程序的名称从invite.rb更改为invite_mailer.rb

在新重命名的invite_mailer.rb文件中，我们将class Invite < ApplicationMailer替换为class InviteMailer < ApplicationMailer

我希望这对可能会遇到类似relation_delegate_class错误的其他Stack Overflow用户有用。

关于ruby-on-rails - Rails 4 : undefined method `relation_delegate_class' for Model:Class，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/32570689/