Question

我有一个使用seed.rb从.txt文件加载的俱乐部和活动（即乐队或棒球）列表。我想在我的视图中创建一个复选框列表，用户可以在其中查看他/她所参与的任何活动。我一直在为活动列表创建迭代时遇到问题，我收到一个“未定义的方法`每个'为nil：NilClass”错误。我的模型叫做Activity。

我的控制器有@activities = Activity.all和

我的观点有＆lt;％@ activities.each do | a | ％GT;

但那条线不起作用。 Activity模型有一个名为：name的字符串属性，如果有帮助的话。有人有想法我可以试试吗？谢谢！

路由。 RB

CollegeConnection::Application.routes.draw do
  devise_for :users

  resources :quizzes
  resources :users
  resources :majors
  resources :activities


  root :to => "users#welcome"
 end

quiz controller:


class QuizzesController < ApplicationController
before_filter :authenticate_user!


# GET /quizzes
# GET /quizzes.json

def index
  @quizzes = Quiz.all

  respond_to do |format|
  format.html # index.html.erb
  format.json { render json: @quizzes }
  end
end

# GET /quizzes/1
# GET /quizzes/1.json
def show
  @quiz = Quiz.find(params[:id])

  respond_to do |format|
  format.html # show.html.erb
  format.json { render json: @quiz }
  end
end

# GET /quizzes/new
# GET /quizzes/new.json
def new
  @quiz = Quiz.new

  respond_to do |format|
    format.html # new.html.erb
    format.json { render json: @quiz }
  end
end

# GET /quizzes/1/edit
def edit
  @quiz = current_user.quizzes.build(params[:id])
end

# POST /quizzes
# POST /quizzes.json
def create
  @quiz = Quiz.new(params[:quiz])
  @quiz.userName=current_user.name
  @activities = Activity.all
  respond_to do |format|
    if @quiz.save
      format.html { redirect_to @quiz, notice: 'Thank You for Taking the Quiz!.' }
      format.json { render json: @quiz, status: :created, location: @quiz }
    else
      format.html { render action: "new" }
      format.json { render json: @quiz.errors, status: :unprocessable_entity }
    end
  end
end

# PUT /quizzes/1
# PUT /quizzes/1.json

def update
  @quiz = Quiz.find(params[:id])

  respond_to do |format|
    if @quiz.update_attributes(params[:quiz])
      format.html { redirect_to @quiz, notice: 'Quiz was successfully updated.' }
      format.json { head :ok }
    else
      format.html { render action: "edit" }
      format.json { render json: @quiz.errors, status: :unprocessable_entity }
    end
  end
end

# DELETE /quizzes/1
# DELETE /quizzes/1.json
def destroy
  @quiz = Quiz.find(params[:id])
  @quiz.destroy

  respond_to do |format|
    format.html { redirect_to quizzes_url }
    format.json { head :ok }
  end
end

端

_form.html.erb测验视图

<%= form_for(@quiz, html: {class: "nice"}) do |f| %>
  <% if @quiz.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@quiz.errors.count, "error") %> 
        prohibited this quiz from being saved:
      </h2>

    <ul>
      <% @quiz.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
    </ul>
    </div>
<% end %>

<div class="field">
  <%= f.label :q1, "Current/Possible Major" %><br />
  <%= f.collection_select(:q1, Major.all, :name, :name) %>
</div>
<div class="field">
  <%= f.label :q2, "Activities" %><br />
  <%= f.collection_select(:q2, Activity.all, :name, :name) %>
</div>


<% @activities.each do |a| %> 
<%= a.check_box :active %> 
<%= a.submit "Update" %> 
<% end %>


<div class="field">
  <%= f.label :q3 %><br />
  <%= f.text_area :q3, class: 'input-text' %>
</div> 

<div class="actions">
  <%= f.submit "Submit" %>
</div>

好的，所以我找到了部分解决方案：

<div class="field">
  <%= f.label :q2, "Activities" %><br />  
  <% for activity in Activity.find(:all) %>
    <div>
      <%= check_box_tag(:q2, activity.name) %> <%=activity.name %>
    </div>
  <% end %>
</div>

它列出了旁边带有名称的所有复选框，但它没有将值设置为q2的答案（问题二的测验属性）我认为我对复选框标签做错了。我尝试了f.check_box但它也无法正常工作。有什么帮助吗？

错误：

NoMethodError in Quizzes#new

Showing /Users/Daniel/Documents/cis196/CollegeConnection/app/views/quizzes/_form.html.erb
where line #24 is raised

undefined method `merge' for "Debate\n":String
Extracted source (around line #24):

21:     <%= f.label :q2, "Activities" %><br />  
22:     <% for activity in Activity.find(:all) %>
23:     <div>
24:        <%= f.check_box(:q2, activity.name) %> <%=activity.name %>
25:     </div>
26:   <% end %>
27:   </div>
Trace of template inclusion: app/views/quizzes/new.html.erb

Rails.root: /Users/Daniel/Documents/cis196/CollegeConnection 

Application Trace | Framework Trace | Full Trace
app/views/quizzes/_form.html.erb:24:in `block (2 levels) in      _app_views_quizzes__form_html_erb__435461842904466959_70320063188680'

app / views / quizzes / _form.html.erb:22:in each' app/views/quizzes/_form.html.erb:22:in块in _app_views_quizzes__form_html_erb__435461842904466959_70320063188680' app / views / quizzes / _form.html.erb：1：in _app_views_quizzes__form_html_erb__435461842904466959_70320063188680' app/views/quizzes/new.html.erb:6:in _ app_views_quizzes_new_html_erb__735256988922435877_70320063679640' app / controllers / quizzes_controller.rb：31：在'new'中请求

参数：

无显示会话转储

显示env转储

响应

接头：

无

测验模型

Class Quiz < ActiveRecord::Base
belongs_to :user

validates :q1, :presence => true
validates :q2, :presence => true
validates :q3, :presence => true

serialize :q2

端

Answer 1

这就是我的想法。您的_form partial是部分的，因为它可能由您的创建视图和编辑视图共享。 _form部分取决于正在初始化的@activities。您只在创建操作中初始化它。尝试这样的事情：

quizzes_controller.rb

QuizzesController < ApplicationController
  before_filter load, :only =>[:create, :edit]
  def load
    @activities = Activity.all
  end
end

然后你可以删除

@activities = Activity.all

来自您的创建操作的

，将在您的创建和编辑操作中初始化@activities。

更新：

check_box_tag有3个（或更多）参数，第一个是元素的id，第二个是要传递的值，THIRD是一个布尔值，如果为true将导致复选框被检查。

所以现在你必须发布你的模型和协会做Quiz'has_many'活动等。

如何从rails中传递给模型的种子数据创建复选框列表

1 个答案: