Question

我有一个简单的项目，我使用以下语法创建了view，controller，model，migration：

rails g scaffold user name:string contact:string

然后我只使用以下命令创建了一个模型：

rails g model event event_name:string event_place:string

然后我在模型中创建了关联，您可以在以下代码中看到。

user.rb类的代码如下：

class User < ActiveRecord::Base
    has_many :events


  attr_accessible :contact, :name, :events_attributes

  accepted_nested_attributes_for :events

end

event.rb类的代码如下：

class Event < ActiveRecord::Base
    belongs_to :user

  attr_accessible :event_name, :event_place
end

index.html.erb的代码如下：

<h1>Listing users</h1>

<table>
  <tr>
    <th>Name</th>
    <th>Contact</th>
    <th></th>
    <th></th>
    <th></th>
  </tr>

<% @users.each do |user| %>
  <tr>
    <td><%= user.name %></td>
    <td><%= user.contact %></td>
    <td><%= link_to 'Show', user %></td>
    <td><%= link_to 'Edit', edit_user_path(user) %></td>
    <td><%= link_to 'Destroy', user, method: :delete, data: { confirm: 'Are you sure?' } %></td>
  </tr>
<% end %>
</table>

<br />

<%= link_to 'New User', new_user_path %>

我的观点中没有改变任何东西......因为脚手架会自行生成。当我在浏览器上运行我的代码时，它显示以下错误：

 NoMethodError in Users#index

Showing /home/wasif/projects/club/app/views/users/index.html.erb where line #12 raised:

undefined method `each' for nil:NilClass

Extracted source (around line #12):

9:     <th></th>
10:   </tr>
11: 
12: <% @users.each do |user| %>
13:   <tr>
14:     <td><%= user.name %></td>
15:     <td><%= user.contact %></td>

这是users_controller.rb

的代码

class UsersController < ApplicationController
  # GET /users
  # GET /users.json
  def index
    @users = user.all

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

  # GET /users/1
  # GET /users/1.json
  def show
    @User = User.find(params[:id])

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

  # GET /user/new
  # GET /user/new.json
  def new
    @user = User.new

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

  # GET /user/1/edit
  def edit
    @user = User.find(params[:id])
  end

  # POST /users
  # POST /users.json
  def create
    @user = User.new(params[:user])

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

  # PUT /users/1
  # PUT /users/1.json
  def update
    @user = User.find(params[:id])

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

  # DELETE /users/1
  # DELETE /users/1.json
  def destroy
    @user = User.find(params[:id])
    @user.destroy

    respond_to do |format|
      format.html { redirect_to user_url }
      format.json { head :no_content }
    end
  end
end

我现在不知道该怎么做，我怎么能删除错误，因为我是初学者所以请帮助我现在该做什么。提前致谢！

Answer 1

你在索引方法中有错误的代码：

应使用

@users = User.all代替@users = user.all

  def index
    @users = User.all

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

Answer 2

请检查数据库，确保表“events”

中有“user_id”列

在模型中关联时出错

2 个答案: