自动加载常量时检测到循环依赖（Rails 4、Ruby 2）

Question

configs/routes.rb Shutters 和 Paints 是 Jobs 的子资源。

resources :jobs do
    resources :shutters
    resources :paints
end

app/models/job.rb 一个Job 包含许多Shutters 和许多Paints。

class Job < ActiveRecord::Base
    has_many :shutters, dependent: :delete_all
    has_many :paints, dependent: :delete_all

    accepts_nested_attributes_for :shutters, allow_destroy: true, :reject_if => lambda { |a| a[:no].blank? }
    accepts_nested_attributes_for :paints, allow_destroy: true, :reject_if => lambda { |a| a[:name].blank? }`

app/models/shutter.rb 一个Shutter 包含属于一个Job 和一个Paint。

class Shutter < ActiveRecord::Base
    belongs_to :job
    belongs_to :paint

app/models/paint.rb Paint 属于一个 Job，但在该作业中可以被许多 Shutters 引用。

class Paint < ActiveRecord::Base
    belongs_to :job
    has_many :shutters

如果数据库中没有Paints，Jobs#show 和Jobs#edit 都可以正常使用代码<%= debug @job.paints %>。但是在添加油漆的那一刻，会引发 RuntimeError，“自动加载常量 PAINT 时检测到循环依赖”。

修复此错误的最佳方法是什么？

编辑：控制器信息

app/controllers/jobs_controller.rb

class JobsController < ApplicationController
    before_action :set_job, only: [:show, :edit, :update, :destroy]

    ...

    # GET /jobs/1
    # GET /jobs/1.json
    def show
    end

    # GET /jobs/new
    def new
        @job = Job.new
        @job.shutters.build
        @job.paints.build
    end

    # GET /jobs/1/edit
    def edit
        @job.shutters.build
        @job.paints.build
    end

app/controllers/shutters_controller.rb

class ShuttersController < ApplicationController
    def new
        @shutter = Shutter.new
    end

    def destroy
        @shutter = Shutter.find(params[:id])
        @job = Job.find(@shutter[:job_id])
        @shutter.destroy
        respond_to do |format|
            format.html {redirect_to @job, notice: 'Shutter was succesfully deleted.' }
        end
    end
end

app/controllers/paints_controller.rb

class PaintsController < ApplicationController
    def new
        @paint = Paint.new
    end

    def destroy
        @paint = Paint.find(params[:id])
        @job = Job.find(@paint[:job_id])
        @paint.destroy
        respond_to do |format|
            format.html {redirect_to @job, notice: 'Paint was succesfully deleted.' }
        end
    end
end

Answer 1

问题不在于这些。实际上，我的Paint 模型包含一个名为:type 的字段，它是元分类或类似的保留关键字。谢天谢地，得到了#RubyOnRails 的好心人的帮助，否则像我这样的新手会尝试从头开始，遇到同样的问题，并且永远不会想到这一点。希望这对未来的 Google 员工有所帮助。提前付款！