Question

我收到此错误：

CycleRoadsController＃destroy中的NoMethodError

未定义的方法`destroy＆＃39;为零：NilClass（rails）。

这是来自控制器的代码，它们包含一种方法＆＃39; destroy＆＃39;：

        respond_to do |format|
      if @cycle_road.save
        format.html { redirect_to @cycle_road, notice: 'Cycle road was successfully created.' }
        format.json { render action: 'show', status: :created, location: @cycle_road }
      else
        format.html { render action: 'new' }
        format.json { render json: @cycle_road.errors, status: :unprocessable_entity }
      end
    end
  end

  def update
    respond_to do |format|
      if @cycle_road.update(cycle_road_params)
        format.html { redirect_to @cycle_road, notice: 'Cycle road was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: 'edit' }
        format.json { render json: @cycle_road.errors, status: :unprocessable_entity }
      end
    end
  end

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

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

    def cycle_road_params
      params.require(:cycle_road).permit(:name, :begin, :finish, :km, :description)
    end
end

有人知道，有什么不对吗？

Answer 1

在调用@cycle_road之前设置实例变量destroy。

目前其nil错误显示为undefined method 'destroy' for nil:NilClass。

根据共享控制器代码，您需要在destroy

的before_action回调中添加set_cycle_road操作

class CycleRoadController < ApplicationController
  before_action :set_cycle_road, only: [:show, :edit, :update, :destroy]
  ## ...                                                         ^
  ##                                                          Add this
end

此回调将在调用@cycle_road操作之前设置destroy实例变量。

Answer 2

正如上一个人提到的那样，@ cycle_road似乎是零。确保您有一个之前的行动：

class CycleRoadController < ApplicationController
  ...
  before_action :set_cycle_road
  ...

确保它针对您的destroy方法运行。即。

before_action :set_cycle_road, only: [:show, :edit, :update, :destroy]

未定义的方法`destroy'为nil：NilClass（rails）

2 个答案: