Question

我是Rails的新手，我一直在漫无目的地围绕stackoverflow徘徊，试图找到解决我的问题的方法，但似乎无法弄明白。我正在做Michael Hartl教程的第10章，当我尝试查看特定用户的配置文件localhost：3000页面时，我收到以下错误消息：

"NoMethodError in Users#show"

接着是

"undefined method `name' for nil:NilClass".

源代码列为show.html.erb文件的第一行，但我看不出代码有什么问题。

主页工作正常，用户索引是可见的，但除此之外它不起作用。我知道这可能意味着@user对象是nil，但我不知道如何解决这个问题。我的Rspec测试也失败了 - 任何帮助都将非常感激。

我的users_controller.rb文件：

 class UsersController < ApplicationController
  before_filter :signed_in_user, only: [:index, :edit, :update, :destroy]
  # Arranges for a particular method to be called before the given actions.
  before_filter :correct_user,    only: [:edit, :update]
  before_filter :admin_user,      only:  :destroy # Restricts the destroy action to admins.

  def new
    @user = User.new
  end

  def create
    @user = User.new(params[:user])
    if @user.save
      sign_in @user
      flash[:success] = "Welcome to the Sample App!"
      redirect_to @user
    else
      render 'new'
    end
  end

  def index
    @users = User.paginate(page: params[:page])
  end

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

  def update
    # @user = User.find(params[:id])
    if @user.update_attributes(params[:user])
      flash[:success] = "Profile updated"
      sign_in @user
      redirect_to @user
    else
      render 'edit'
    end
  end

  def destroy
    User.find(params[:id]).destroy
    flash[:success] = "User destroyed."
    redirect_to users_url
  end

  private

    # def signed_in_user
    #   unless signed_in?
    #     store_location
    #     redirect_to signin_url, notice: "Please sign in."
    #   end
    # end

    def correct_user
      @user = User.find(params[:id])
      redirect_to(root_path) unless current_user?(@user)
    end

    def admin_user
      redirect_to(root_path) unless current_user.admin?
    end

    def show
      @user = User.find(params[:id])
      @microposts = @user.microposts.paginate(page: params[:page])
    end
end

我的show.html.erb文件：

<% provide(:title, @user.name) %>
<div class="row">
  <aside class="span4">
    <section>
      <h1>
        <%= gravatar_for @user %>
        <%= @user.name %>
      </h1>
    </section>
  </aside>
  <div class="span8">
    <% if @user.microposts.any? %>
      <h3>Microposts (<%= @user.microposts.count %>)</h3>
      <ol class="microposts">
        <%= render @microposts %>
      </ol>
      <%= will_paginate @microposts %>
    <% end %>
  </div>
</div>

和users_helper.rb

module UsersHelper

    # Returns the Gravatar (http://gravatar.com/) for the given user.
  def gravatar_for(user, options = { size: 50 })
    gravatar_id = Digest::MD5::hexdigest(user.email.downcase)
    size = options[:size]
    gravatar_url = "https://secure.gravatar.com/avatar/#{gravatar_id}?s=#{size}"
    image_tag(gravatar_url, alt: user.name, class: "gravatar")
  end
end

Answer 1

@user是零。因为没有id的记录（params [：id]）。这就是为什么会出现这个错误。

 <h1>
 <%= gravatar_for @user %>
 <%= !@user.nil? @user.name : "" %>
 </h1>


         It will check whether the @user having any record, if its having it will display it's name else it will display empty.

Answer 2

您的查询找不到用户：

@user = User.find(params[:id])

显然会返回nil。

请检查具有给定ID的用户是否存在。此外，如果没有找到任何对象，您应该安全地失败：

<% if @user.nil? %>
  <% provide(:title, 'Not found') %>
  No user with that ID has been found.
<% else %>
  <!-- Contents of your current show.html.erb -->
<% end %>

Rails：用户#show中的NoMethodError

2 个答案: