Rails NoMethodError 'each' 尝试销毁记录时

Question

我有一个带有一些表（答案、问题、项目）的 rails 应用程序，答案通过外键链接到问题，我的问题控制器中的销毁方法定义如下：

def destroy
        @pregunta = Question.find(params[:id])
        @pregunta.destroy
        flash[:danger] = "Se ha borrado la pregunta"
        redirect_to questions_path
    end 

我的 ANSWER 模型有以下限制：

belongs_to :question, :dependent => :destroy
    has_many :answers_projects, :dependent => :destroy
    has_many :projects, through: :answers_projects, :dependent => :destroy

但是当我尝试像这样调用我的销毁方法时（在我看来）：

<% @preguntas.each do |pregunta| %>
    <tr>
      <td><%= pregunta.question %></td>
      <td><%= pregunta.get_process_name %></td>
      <td><%= pregunta.input %></td>
      <td><%= pregunta.count_op %></td>
      <td><%= pregunta.area %></td>
      <td><%= link_to 'Mostrar', question_path(pregunta), class: "btn btn-xs btn-info" %></td>
      <td><%= link_to 'Editar', edit_question_path(pregunta) , class: "btn btn-xs btn-warning"%></td>
      <td><%= link_to 'DELETE',question_path(pregunta),method: :delete, data: {confirm: '¿Estás seguro de que deseas eliminar la pregunta? Esta acción no se puede deshacer'}, class: "btn btn-xs btn-danger"%></td>

我可以在我的开发环境中销毁记录，但在我的部署环境中，我的 Heroku 日志中出现以下错误：

AnswersProject Load (0.7ms)  SELECT "answers_projects".* FROM "answers_projects" WHERE "answers_projects"."answer_id" = $1  [["answer_id", 95]]
2018-02-02T23:14:19.329550+00:00 app[web.1]: [bb557967-7424-414b-9684-b31ad439936a]    (0.6ms)  ROLLBACK
2018-02-02T23:14:19.337619+00:00 app[web.1]: [bb557967-7424-414b-9684-b31ad439936a] Completed 500 Internal Server Error in 140ms (ActiveRecord: 30.3ms)
2018-02-02T23:14:19.338990+00:00 app[web.1]: [bb557967-7424-414b-9684-b31ad439936a]   
2018-02-02T23:14:19.339160+00:00 app[web.1]: [bb557967-7424-414b-9684-b31ad439936a] NoMethodError (undefined method `each' for #<Answer:0x00000004d173e8>):
2018-02-02T23:14:19.339198+00:00 app[web.1]: [bb557967-7424-414b-9684-b31ad439936a]   
2018-02-02T23:14:19.339242+00:00 app[web.1]: [bb557967-7424-414b-9684-b31ad439936a] app/controllers/questions_controller.rb:77:in `destroy'

如您所见，我收到 NoMethodError（仅在部署应用程序后发生）可能是什么原因造成的，如何解决？ 如果需要，我会从我的控制器和模型中发布更多代码，在此先感谢 :)

编辑 完整的问题控制器：

class QuestionsController < ApplicationController
    before_action :require_user
    before_action :require_project
    before_action :require_user, except: [:new, :create]
    before_action :current_project, only: [:index]
    def index
        @preguntas = Question.all.order(:process)
        @project_id = request.original_url.split('.').last
        set_current_project(@project_id)
    if(@project_id.include? "http")
    @project_id = "0"
    end
        if(@project_id != "0")
            @proyecto = Project.find(@project_id)
        end 
    end

def show
    @pregunta = Question.find(params[:id])
    @opciones = Option.where(question_id: @pregunta)
end

def new
puts "HELLO EVERYONE NEW QUESTION"
  @pregunta = Question.new
    for option in @pregunta.options
        option.question_id = 1
        option.build
    end
end

def create
puts "HELLO EVERYONE CREATE QUESTION"
    @pregunta = Question.new(pregunta_params)
    if @pregunta.save
    @counter = 0
    @step = 1.to_f / @pregunta.options.count
    for option in @pregunta.options
        @counter = @counter + 1
        if @counter == @pregunta.options.count
            option.update_value(1.to_f)
        else
            option.update_value(@step * @counter)
        end
    end
         redirect_to @pregunta
    else
         render 'new'
    end
end
    def edit
        @pregunta = Question.find(params[:id])
    end 

    def update
puts "HELLO EVERYONE UPDATE UPDATE"
      @pregunta = Question.find(params[:id])
      @pregunta.options.build
      if @pregunta.update(pregunta_params)
        @counter = 0
            @step = 1.to_f / @pregunta.options.count
            for option in @pregunta.options
                @counter = @counter + 1
                if @counter == @pregunta.options.count
                    option.update_value(1.to_f)
                else
                    option.update_value(@step * @counter)
                end
            end
        redirect_to @pregunta
      else
        render 'edit'
      end
    end


     def destroy
        @pregunta = Question.find(params[:id])
        Answer.where(:question_id => @pregunta.id).destroy_all
        @pregunta.destroy
        flash[:danger] = "Se ha borrado la pregunta"
        redirect_to questions_path
    end 

    def require_same_user 
        set_project
        if current_user != @project.user && !@current_user.admin?
            flash[:danger] = "Solo puedes editar tus artículos"
            redirect_to root_path
        end 
    end 

    def require_project
        if current_user.projects.count <1 && !current_user.admin?
            redirect_to root_path
        end 
    end 

    private
        def pregunta_params
            params.require(:question).permit(:question, :value, :process, :area, :input, options_attributes: Option.attribute_names.map(&:to_sym).push(:_destroy))
        end
end

编辑 完整问题模型：

class Question < ApplicationRecord  
    has_many :options, dependent: :destroy
    accepts_nested_attributes_for :options, allow_destroy: true, reject_if: proc { |att| att['description'].blank? }
    validates :question, presence: true
        validates :value, presence: true, length: { minimum: 1 }
        validates :area, presence: true, length: { minimum: 3 }

        def count_op
            Option.where("description IS NOT NULL").where(question_id: self.id).count
        end

        def get_op
            Option.where("description IS NOT NULL").where(question_id: self.id)
        end
        def get_process_name
            case self.process
                when 1 
                    "1 - Identificación de grupo"
                when 2
                    "2 - Reflexión de desarrollo comunitario"
                when 3 
                    "3 - Problemáticas comunitarias - priorización"
                when 4 
                    "4 - Plan de trabajo comunitario"
                when 5 
                    "5 - Desarrollo de actividades y proyectos"
                when 6 
                    "6 - Operación de proyectos y seguimiento a cumplimiento de metas"
                when 7 
                    "7 - Seguimiento a proyectos comunitarios"
                when 8 
                    "8 - Fortalecimiento - operación de grupo"
                when 9 
                    "9 - Capacitación metodológica para vinculación y desarrollo comunitario"
                when 10 
                    "10 - Creación de redes y alianzas comunitarias"
                when 11 
                    "11 - Realización de planes de desarrollo local"
                when 12
                    "12 - Seguimiento a proyectos"
                when 13
                    "13 - Fortalecimiento operación de grupo"
                when 14
                    "14 - Creación de redes y alianzas institucionales"
                else
                    "Error en la fase"
            end
        end
end

Answer 1

我认为当你创建你的模型时，.answer_projects 是 nil，所以当它试图破坏 .projects 时，它找不到与 .answer_projects 关联的每个模型。尝试改变

has_many :answers_projects, :dependent => :destroy
has_many :projects, through: :answers_projects, :dependent => :destroy

到

has_many :answers_projects
has_many :projects, through: :answers_projects

Answer 2

你为什么回答belongs_to :question, :dependent => :destroy？ 当你破坏一个答案时，你想破坏一个问题吗？ 你对 has_many 的答案有疑问吗？

这可能是问题所在。

如果没有，我也发现了一些改进。您正在定义很多实例变量（@project_id、@counter、@step 等）。您是否需要在视图中访问这些变量？为什么不直接使用project_id、counter、step？

编辑

在 QuestionsController#destroy 中发布错误后：为什么不在 Question 模型中添加 question has_many :answersdependent destroy？这样你就不需要在销毁问题之前执行 destroy_all 了。

class Question < ApplicationRecord  
  has_many :options, dependent: :destroy
  has_many :answers, dependent: :destroy
  accepts_nested_attributes_for :options, allow_destroy: true, reject_if: proc { |att| att['description'].blank? }
  validates :question, presence: true
  validates :value, presence: true, length: { minimum: 1 }
  validates :area, presence: true, length: { minimum: 3 }

问题控制器

def destroy
  @pregunta = Question.find(params[:id])
  @pregunta.destroy
  flash[:danger] = "Se ha borrado la pregunta"
  redirect_to questions_path
end