我正在尝试关注 Creating a Scoped Invitation System for Rails 的coderwall教程。
在我的Rails 4应用程序中，我有以下模型：
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
以下是我的模型与教程中的模型之间的对应关系：
User＆lt; =＆gt; User Calendar＆lt; =＆gt; UserGroup Administration＆lt; =＆gt; Membership Invite＆lt; =＆gt; Invite 我现在正在发表新邀请部分：
Invite模型已使用before_create过滤器和generate_token方法进行了更新。Invites控制器已使用create操作进行了更新。但是，当我访问日历编辑视图以填写邀请表单时，我收到以下错误：
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。
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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
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更新2 ：在this question中，作者解释说问题可能来自CanCanCan＆amp; Rolify。我没有使用这些宝石，但我使用的是Pundit。认为这在我的问题中是有用的。
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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，因为给定role的{{1}}仅存在于user表中，对于给定的{ {1}}：如果administration被Rails自动解释为calendar，那么这可能导致错误吗？
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更新4 ：这是CalendarsController的内容：
:recipient_role- - - -
更新5 ：这是服务器日志：
recipient.role- - - -
更新6 ：我刚才意识到我没有
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
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)
控制器中的：这可能是问题的根源吗？
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了解此错误消息的含义以及如何解决此问题？
答案 0 :(得分：20)
这个问题很难识别，特别是从问题的内容来看。
问题
我收到undefined method 'relation_delegate_class' for Invite:Class错误的原因是因为Invite不再被Rails认为是模型。
问题的根本原因
当我创建Invite邮件程序时，我运行了rails g mailer Invite而不是rails g mailer InviteMailer。
因此，Invite作为邮件程序覆盖Invite作为模型，因此只要将方法应用于Invite模型的实例，就会产生错误。
我们如何制作出
我的一位朋友，比我更熟悉编程，通过调整导致错误的@invite = @calendar.invites.build行来确定问题。
这导致我们最终在rails控制台中运行Invite.first：虽然我们应该有Invite类的实例，或者nil，但实际上我们遇到了错误。
由于.first应该是任何ActiveRecord模型的有效方法，我们意识到Invite并不被Rails视为模型。
我们如何修复
一旦我们确定了问题，修复它就非常简单了：
Invite邮件的名称从invite.rb更改为invite_mailer.rb invite_mailer.rb文件中，我们将class Invite < ApplicationMailer替换为class InviteMailer < ApplicationMailer 我希望这对可能会出现类似relation_delegate_class错误的其他Stack Overflow用户有用。
答案 1 :(得分：0)
如果您忘记从ActiveRecord继承模型，也会发生这种情况。 因此，它变成了一个简单的红宝石类。
class MyPlainModel
end