未定义的方法：显示列表时的名称（ruby on rails）

Question

我创建了一个用户个人资料页面，其中显示了用户创建的所有列表。每个列表都有一个“显示”链接，该链接链接到一个新页面，该页面在不同的页面上单独显示列表。我让它为用户个人资料页面工作。 我正在使用这个链接

<li><%= link_to "Show", user_listing_path(name: @user.name, id: listing.id) %></li>

但是，现在我想创建一个列表索引页面，显示每个用户的所有列表。每个列表都应该有一个“显示”链接，该链接链接到单独显示列表的页面。在用户个人资料页面上有效的相同链接在列表索引页面上无效。

我收到以下错误 undefined method `name' for nil:NilClass 它指向

有人知道为什么吗？

用户展示文件（show.html.erb）

<div class= "showuser">
                <div class="error-message">
      <% flash.each do |key, value| %>
        <div class="alert alert-<%= key %>"><%= value %></div>
      <% end %>
      </div>



<h4>
<%= gravatar_for @user %>
<%= @user.name %>
</h4>


        <div class="span 8">
            <% if @user.listings.any? %>
            <h3> Job Posts (<%= @user.listings.count %>)</h3>
            <ol class="listings">
                <%= render @listings %>
                <% @listings.each do |listing| %>
        <% end %>
            </ol>
            <%= will_paginate @listings %>
            <% end %>
    </div>
</div>

列表文件（_listing.html.erb）

<li>
    <h4><%= listing.title %></h4>
    <p><%= listing.location %></h4><br>
    <span class="content"><%= listing.description %></span>
    <span class="timestamp">
        Posted <%= time_ago_in_words(listing.created_at) %> ago
    </span>
    <li><%= link_to "Show", user_listing_path(name: @user.name, id: listing.id) %></li>
    <% if current_user?(listing.user) %>
    <li><%= link_to "Edit", edit_listing_path %></li>
     <%= link_to "delete", listing, method: :delete,
                                    data: { confirm: "You sure?" },
                                    title: listing.description %>
    <% end %>
</li>

上市控制器

class ListingsController < ApplicationController
    before_action :signed_in_user, only: [:create, :destroy, :edit, :update]
    before_action :correct_user,   only: [:destroy, :edit, :update]

    def create
        @listing = current_user.listings.build(listing_params)
        if @listing.save
            flash[:success] = "Job Post created"
            redirect_to current_user
            else
                render 'listings/new'
            end
        end



        def edit
        end

    def update
        if @listing.update_attributes(listing_params)
        flash[:success] = "Listing updated"
        redirect_to @listing
    else 
      render 'edit'
    end
  end

        def show
            @user = User.find_by_name(params[:name])
            @listing = Listing.find_by_id(params[:id])

        end

        def new
            @listing = Listing.new
            @listings = Listing.paginate(page: params[:page])
        end

    def destroy 
        @listing.destroy
        redirect_to current_user
    end

    def index
    @listings = Listing.all
    @listings = Listing.paginate(page: params[:page])
    @user = User.find_by_name(params[:name])
    @listing = Listing.find_by_id(params[:id])
  end



    private 



    def listing_params
        params.require(:listing).permit(:description, :location, :title)
    end

    def correct_user
        @listing = current_user.listings.find_by(id: params[:id])
        redirect_to current_user if @listing.nil?
    end

end

列表显示文件 (show.html.erb) 单独显示列表

<div class="show_listing">

    <div class="col-md-6">
    <div class="col-md-6">
        <h3><%= @listing.title %></h3>
        <h3><%= @listing.location %></h3>
        <p><%= @listing.description %></p><br>
        <div class="center">
        <%= link_to "Apply Now", '#', class: "btn btn-info", data: {no_turbolink: true} %>
    </div>
    </div>
</div>
</div>

<div class="show_link_position">
<% if current_user == @listing.user %>
<%= link_to 'Edit', edit_listing_path, class: "btn btn-link" %> |
<% end %>
<%= link_to 'Back', current_user, class: "btn btn-link" %>
</div>

列出索引文件（index.html.erb）

<div class="top">
  <div class="categories-container">
     <div class="boxed grid-3 category-link ">
    <li><%= link_to "Find Jobs",  findjobs_path, class: "category-link"%></li>
              <li><%= link_to "Post Jobs",  new_path, class: "category-link" %></li>
              <li><%= link_to "Find Jobs",  findjobs_path, class: "category-link" %></li>
              <li><%= link_to "Post Jobs",  new_path, class: "category-link" %></li>
              <li><%= link_to "Find Jobs",  findjobs_path, class: "category-link" %></li>
              <li><%= link_to "Post Jobs",  new_path, class: "category-link" %></li>
              <li><%= link_to "Find Jobs",  findjobs_path, class: "category-link" %></li>
              <li><%= link_to "Post Jobs",  new_path, class: "category-link" %></li>
        </div>
    </div>



<div class="table-container">
<div class= "grid-8 grid-moved">
  <% @listings.each do |listing| %>

  <h4><%= listing.title %></h4>
  <h5> <%= listing.user.name %>, Posted <%= time_ago_in_words(listing.created_at) %> ago</h5>
    <h5>Job Description:</h5>
      <p><%= listing.description %></p>
    <p>Location: <%= listing.location %></p>
    <li><%= link_to "Show", user_listing_path(name: @user.name, id: listing.id) %></li>
    <br><hr><br>

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


<div class="container">
  <div class="pagination">
    <%= will_paginate @listings %>
  </div>
</div>

路线

Rails.application.routes.draw 做 资源：用户 资源：会话，仅：[：new，：create，：destroy] 资源：列表

root 'static_pages#home'

  match '/signup',  to: 'users#new',            via: 'get'
  match '/signin',   to: 'sessions#new',          via: 'get'
  match '/signout', to: 'sessions#destroy',     via:'delete'
  match '/help',      to: 'static_pages#help',    via: 'get'
  match '/contact',   to: 'static_pages#contact',  via: 'get'
  match '/about',     to: 'static_pages#about',   via: 'get' 
  match '/new',     to: 'listings#new',   via: 'get' 
  match '/users/:name/:id', to: 'listings#show', via: :get, as: :user_listing
  match '/findjobs',     to: 'listings#index',   via: 'get' 

如果我遗漏了任何重要信息，请告诉我。

Answer 1

您还没有在控制器中定义@user。

在下一行中，您可以适当地访问列表用户，如下所示： <% if current_user?(listing.user) %>

您只需将代码调整为如下所示：

<li><%= link_to "Show", user_listing_path(name: listing.user.name, id: listing.id) %></li>

有意义吗？

Answer 2

试试：

<li><%= link_to "Show", user_listing_path(@user, listing) %></li>

在你的控制器上：

def show 
  @user = User.find(params[:id)
  @listing = Listing.find(params[:id])
end