Form_for错误:未定义的方法`id'为零:NilClass

时间:2016-06-01 19:00:52

标签: ruby-on-rails

我正在构建一个应用程序,其中包含锻炼模型,每个锻炼has_many练习以及每个锻炼has_many报告。

我的路线如下:

        workouts GET    /workouts(.:format)                    workouts#index
                 POST   /workouts(.:format)                    workouts#create
     new_workout GET    /workouts/new(.:format)                workouts#new
    edit_workout GET    /workouts/:id/edit(.:format)           workouts#edit
         workout GET    /workouts/:id(.:format)                workouts#show
                 PATCH  /workouts/:id(.:format)                workouts#update
                 PUT    /workouts/:id(.:format)                workouts#update
                 DELETE /workouts/:id(.:format)                workouts#destroy
       exercises GET    /exercises(.:format)                   exercises#index
                 POST   /exercises(.:format)                   exercises#create
    new_exercise GET    /exercises/new(.:format)               exercises#new
   edit_exercise GET    /exercises/:id/edit(.:format)          exercises#edit
        exercise GET    /exercises/:id(.:format)               exercises#show
                 PATCH  /exercises/:id(.:format)               exercises#update
                 PUT    /exercises/:id(.:format)               exercises#update
                 DELETE /exercises/:id(.:format)               exercises#destroy
         reports POST   /reports(.:format)                     reports#create
          report DELETE /reports/:id(.:format)                 reports#destroy

我玩弄了路线,但它造成的问题比解决的还多,所以它们仍然是这样的:

  resources :workouts
  resources :exercises
  resources :reports, only: [:create, :destroy]

在我的workouts#show页面上,我有一个链接可以为该锻炼添加练习:

<%= link_to 'Add/Edit Exercises', exercises_path(@workout) %>

当我点击链接时,出现以下错误:

undefined method `id' for nil:NilClass

当我点击该链接时,它应该转到我的exercises#index页面:

<h1>Current Exercises:</h1>
  <% @exercises.each do |exercise| %>
    <p><%= exercise.name %> (<%= link_to "Delete #{exercise.name}", exercise_path(exercise), method: :delete, data: { confirm: 'Are you sure?' } %>)</p>
  <% end %>
<h1>Add New Exercises:</h1>
  <%= render 'exercises/form' %>

exercises/_form.html.erb上,在指定的行上调用错误:

<div class="row">
  <div class="col-xs-10 col-xs-push-1">
    <%= form_for @exercise,
        :url => { :controller => "exercises",
        :action => :create,
        :workout_id => @workout.id } do |f| %> <!-- error called on this line -->
      <div class="form-group">
        <%= f.label :name, class: 'sr-only' %>
        <%= f.text_field :name, class: 'form-control', placeholder: "Enter exercise name" %>
      </div>

      <div class="form-group col-xs-4">
        <p><%= f.label :needs_seconds, class: 'sr-only' %>
        <%= f.check_box :needs_seconds, class: 'check_box' %> Report seconds?</p>
      </div>

      <div class="form-group col-xs-4">
        <p><%= f.label :needs_reps, class: 'sr-only' %>
        <%= f.check_box :needs_reps, class: 'check_box' %> Report reps?</p>
      </div>

      <div class="form-group col-xs-4">
        <p><%= f.label :needs_weight, class: 'sr-only' %>
        <%= f.check_box :needs_weight, class: 'check_box' %> Report weight?</p>
      </div>

      <div class="text-center"><%= f.submit "Create Exercise", class: 'btn btn-primary' %></div>

    <% end %>
  </div>
</div>

有关导致此错误的原因的任何见解?这是我的训练控制员:

class WorkoutsController < ApplicationController
  def index
    @workouts = Workout.all
  end

  def show
    @workout = Workout.friendly.find(params[:id])
    @exercise = Exercise.new
    @report = Report.new
  end

  def new
    @workout = Workout.new
    @workout.user_id = current_user
  end

  def create
    @workout = Workout.new(workout_params)
    @workout.user = current_user

    if @workout.save
      flash[:notice] = "Workout was saved successfully."
      redirect_to @workout
    else
      flash.now[:alert] = "Error creating workout. Please try again."
      render :new
    end
  end

  def edit
    @workout = Workout.friendly.find(params[:id])
    @workout.user_id = current_user
  end

  def update
    @workout = Workout.friendly.find(params[:id])

    @workout.name = params[:workout][:name]
    @workout.workout_type = params[:workout][:workout_type]
    @workout.teaser = params[:workout][:teaser]
    @workout.description = params[:workout][:description]
    @workout.video = params[:workout][:video]
    @workout.difficulty = params[:workout][:difficulty]
    @workout.trainer = params[:workout][:trainer]
    @workout.user_id = params[:workout][:user_id]

    if @workout.save
       flash[:notice] = "Workout was updated successfully."
      redirect_to @workout
    else
      flash.now[:alert] = "Error saving workout. Please try again."
      render :edit
    end
  end

  def destroy
    @workout = Workout.friendly.find(params[:id])

    if @workout.destroy
      flash[:notice] = "\"#{@workout.name}\" was deleted successfully."
      redirect_to action: :index
    else
      flash.now[:alert] = "There was an error deleting the workout."
      render :show
    end
  end

  private
  def workout_params
    params.require(:workout).permit(:name, :workout_type, :teaser, :description, :video, :difficulty, :trainer, :user_id)
  end
end

这是练习控制器:

class ExercisesController < ApplicationController
  before_action :authenticate_user!


  def index
    @exercises = Exercise.all
  end

  def new
    @exercise = Exercise.new
  end

  def create
    @workout = Workout.friendly.find(params[:workout_id])
    exercise = @workout.exercises.new(exercise_params)
    exercise.user = current_user

    if exercise.save
      flash[:notice] = "Results saved successfully."
      redirect_to [@workout]
    else
      flash[:alert] = "Results failed to save."
      redirect_to [@workout]
    end
  end

  def destroy
    @workout = Workout.friendly.find(params[:workout_id])
    exercise = @workout.exercises.find(params[:id])

    if exercise.destroy
      flash[:notice] = "Exercise was deleted successfully."
      redirect_to [@workout]
    else
      flash[:alert] = "Exercise couldn't be deleted. Try again."
      redirect_to [@workout]
    end
  end

  private

  def exercise_params
    params.require(:exercise).permit(:name, :needs_seconds, :needs_weight, :needs_reps)
  end

  def authorize_user
    exercise = Exercise.find(params[:id])
    unless current_user == current_user.admin?
      flash[:alert] = "You do not have permission to create or delete an exercise."
      redirect_to [exercise.workout]
    end
  end
end

这是服务器日志:

Started GET "/exercises.abs-0002" for ::1 at 2016-06-01 13:10:33 -0700
Processing by ExercisesController#index as 
  User Load (0.1ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ?  ORDER BY "users"."id" ASC LIMIT 1  [["id", 1]]
  Workout Load (0.1ms)  SELECT  "workouts".* FROM "workouts" WHERE "workouts"."id" IS NULL LIMIT 1
  Exercise Load (0.1ms)  SELECT "exercises".* FROM "exercises"
  Rendered exercises/_form.html.erb (9.6ms)
  Rendered exercises/index.html.erb within layouts/application (18.4ms)
Completed 500 Internal Server Error in 33ms (ActiveRecord: 0.3ms)

NoMethodError - undefined method `id' for nil:NilClass:
  app/views/exercises/_form.html.erb:4:in `block in _app_views_exercises__form_html_erb___1550785662008061170_70245396037240'
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  actionview (4.2.5) lib/action_view/helpers/form_helper.rb:444:in `form_for'
  app/views/exercises/_form.html.erb:3:in `_app_views_exercises__form_html_erb___1550785662008061170_70245396037240'
  actionview (4.2.5) lib/action_view/template.rb:145:in `block in render'
  activesupport (4.2.5) lib/active_support/notifications.rb:166:in `instrument'
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  activesupport (4.2.5) lib/active_support/notifications.rb:164:in `block in instrument'
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  actionview (4.2.5) lib/action_view/helpers/rendering_helper.rb:35:in `render'
  app/views/exercises/index.html.erb:7:in `_app_views_exercises_index_html_erb___2271140629366515446_70245347113980'
  actionview (4.2.5) lib/action_view/template.rb:145:in `block in render'
  activesupport (4.2.5) lib/active_support/notifications.rb:166:in `instrument'
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  actionview (4.2.5) lib/action_view/template.rb:143:in `render'
  actionview (4.2.5) lib/action_view/renderer/template_renderer.rb:54:in `block (2 levels) in render_template'
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  actionpack (4.2.5) lib/action_controller/metal/instrumentation.rb:44:in `block (2 levels) in render'
  activesupport (4.2.5) lib/active_support/core_ext/benchmark.rb:12:in `block in ms'
  /Users/elizabethbayardelle/.rbenv/versions/2.2.4/lib/ruby/2.2.0/benchmark.rb:303:in `realtime'
  activesupport (4.2.5) lib/active_support/core_ext/benchmark.rb:12:in `ms'
  actionpack (4.2.5) lib/action_controller/metal/instrumentation.rb:44:in `block in render'
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  activerecord (4.2.5) lib/active_record/railties/controller_runtime.rb:25:in `cleanup_view_runtime'
  actionpack (4.2.5) lib/action_controller/metal/instrumentation.rb:43:in `render'
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1 个答案:

答案 0 :(得分:0)

link_to中的workouts#show如下所示:

<%= link_to 'Add/Edit Exercises', exercises_path(workout_id: @workout.id) %>

<强> exercises_controller.rb

def index
    @workout = Workout.find_by_id(params[:workout_id])
    @exercise = Exercise.new
    @exercises = Exercise.all
end

您可以在exercises/_form.html.erb的隐藏字段中传递 workout_id ,如下所示:

<%= form_for @exercise do |f| %>
    <%= f.hidden_field :workout_id, @workout.id %>
<% end %>   

并且,将workout_id包含在您的强项中,如下所示:

def exercise_params
    params.require(:exercise).permit(:name, :needs_seconds, :needs_weight, :needs_reps, :workout_id)
end