Question

我有一个嵌入式mongoid类“Option”，我想用以下方式初始化：

@option = @ event.options.new（'yes'）

class Option

  include Mongoid::Document

  field :content, type: String

  embedded_in :event

  def initialize(content)
    @content = content
  end
end

所以我在上面添加了构造函数，但是我收到以下错误：

EventsController中的NoMethodError #new undefined method` []'for 零：NilClass

我错过了什么？

使用rails 4 ...

编辑：这里要求的是控制器代码：

class EventsController < ApplicationController
      before_action :set_event, only: [:show, :edit, :update, :destroy]

      # GET /events
      # GET /events.json
      def index
        @events = Event.all
      end

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

      # GET /events/new
      def new
        @event = Event.new

        @event.invitees << @event.invitees.build
        @event.options  << @event.options.build
        #end
      end

      # GET /events/1/edit
      def edit
      end

      # POST /events
      # POST /events.json
      def create

        # TODO: adapt event_params and filter right
        #@event = Event.create(event_params)
        @event = Event.new(params[:event])

        respond_to do |format|
          if @event.save
            #TODO: Save users attached to event in user collection
            format.html { redirect_to @event, notice: 'Event was successfully created.' }
            format.json { render action: 'show', status: :created, location: @event }
          else
            format.html { render action: 'new' }
            format.json { render json: @event.errors, status: :unprocessable_entity }
          end
        end
      end

      # PATCH/PUT /events/1
      # PATCH/PUT /events/1.json
      def update
        respond_to do |format|
          if @event.update(event_params)
            format.html { redirect_to @event, notice: 'Event was successfully updated.' }
            format.json { head :no_content }
          else
            format.html { render action: 'edit' }
            format.json { render json: @event.errors, status: :unprocessable_entity }
          end
        end
      end

      # DELETE /events/1
      # DELETE /events/1.json
      def destroy
        @event.destroy
        respond_to do |format|
          format.html { redirect_to events_url }
          format.json { head :no_content }
        end
      end

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

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

Answer 1

这是因为您的field :content, type: String尚未初始化

您需要在super()方法的第一行调用initialize，然后您才能在构造函数中更改content的值

尝试：

def initialize(content)
   super()
   self.content = content
end

访问嵌入式mongoid模型类中的构造函数时出错

1 个答案: