用于 nil:NilClass 的 Rails 未定义方法“model_name”

Question

我有一个带有 2 个控制器 instructors 和 requests 的小型 Rails 站点。 instructors 只能由站点管理员访问以管理和管理它们（所有方法都通过设备进行身份验证）。第二个控制器 instructors 是访​​问访问站点以查看列出的讲师并为他们选择的讲师创建请求的方式。我在创建应保存 name、phone 和 email message 以及从请求显示页面中选择 instructor_id。我希望我的描述清楚。

谢谢。

请求控制器

class RequestsController < ApplicationController
  def index
    if params[:search].present?
      @instructors = Instructor.near(params[:search], 50)
    else
      # Shows all listed instructors by the created date.
      @instructors = Instructor.order('created_at DESC')
    end
  end

  def show
    @instructor = Instructor.find(params[:id])
  end

  def new
    @request = Request.new
  end

  def create
    @request = Request.new(request_params)
    #@request = Request.new(request_params)
    if @request.save
      flash[:success] = "Request has been submited!"
    else
      flash[:alert] = "Something is went wrong!"
    end
  end

  private

  def request_params
    params.require(:request).permit(:name, :email, :phone, :message)
  end
end

请求显示

<header><h1 class="display-4"><%= @instructor.name %></h1></header>

      <h3>Address: <%= @instructor.address %></h3>
      <h3>Car Model: <%= @instructor.car %></h3>
      <hr>
      <%= simple_form_for(@instructor, :url =>{ :action => "create" }) do |f| %>
        <%= f.input :name, label: "Your name" %>
        <%= f.input :email %>
        <%= f.input :phone, label: "Phone number" %>
        <%= f.input :message, as: :text %>
        <br>
        <%= f.button :submit, class: "btn btn-danger" %>
      <% end %>
      <br>
      <br>

教师控制器

class InstructorsController < ApplicationController
      # Admin is required to login to access any action on this controller
      before_action :authenticate_admin! # except: [:action, :action] to unlock any action

      def index
        @instructors = Instructor.order('created_at DESC')
      end

      def show
        find_instructor
      end

      def new
        @instructor = Instructor.new
      end

      def update
        find_instructor
        if @instructor.update(instructor_params)
          redirect_to @instructor
          flash[:notice] = "Instructor changes has been saved."
        else
          render 'edit'
        end
      end

      def create
        @instructor = Instructor.new(instructor_params)
        if @instructor.save
          flash[:notice] = "Instructor has been saved!"
          redirect_to instructors_path
        else
          render 'new'
          flash_error('New instructor hasn\'t been saved.')
        end
      end

      def edit
        find_instructor
      end

      def destroy
        find_instructor
         if @instructor.destroy
           redirect_to root_path
           flash[:notice] = "The instructor has been deleted."
         else
           flash_error('Instructor hasn\'t been deleted.')
         end
      end

        private

        def flash_error(message) # Takes the of the error message as an argument
          flash[:alert] = "Something went wrong!, #{message}
                           Please make sure you submitting valid data and try again"
        end

        def find_instructor
          @instructor = Instructor.find(params[:id])
        end

        def instructor_params
           params.require(:instructor).permit(:name, :car, :address, :manual, :auto)
        end
    end
           flash_error('Instructor hasn\'t been deleted.')
         end
      end

        private

        def flash_error(message) # Takes the of the error message as an argument
          flash[:alert] = "Something went wrong!, #{message}
                           Please make sure you submitting valid data and try again"
        end

        def find_instructor
          @instructor = Instructor.find(params[:id])
        end

        def instructor_params
           params.require(:instructor).permit(:name, :car, :address, :manual, :auto)
        end
    end

导师模式

class Instructor < ApplicationRecord
  has_many :requests
  geocoded_by :address
  after_validation :geocode, if: ->(obj){ obj.address.present? and obj.address_changed? }
end

请求模型

class Request < ApplicationRecord
  belongs_to :instructor
end

Answer 1

我相信错误来自显示视图中的simple_form_for，因为@instructor 为零。

您从以下位置获得该变量：

@instructor = Instructor.find(params[:id])

您应该进行测试，确保存在一个具有随参数发送的 id 的 Instructor。