Question

我为新手问题道歉，这些问题对于铁路来说仍然相对较新。我试图向所有喜欢我特定帖子的用户展示。我看了一下这个类似的问题How to list the users who LIKE a given Post，但它无法解决我的问题。我在下面列出了所有相关的简单代码 - 非常感谢你们！

项目控制器

class ItemsController < ApplicationController
    before_action :authenticate_user!, only: [:new, :create]
    before_action :set_item, only: [:show, :edit, :update, :destroy, :share]

    def index    
        @items = Item.order("created_at DESC")
    end
end

Index.html.erb

<% if user_signed_in? %>
    <%= image_tag current_user.avatar, width: 70, class: "css-style"  %>
    <br>
    <strong><%= link_to current_user.username, current_user, class: "profile-style" %></strong>
    <ul><!--Trying to show all the users who have liked my specific posts here -->
    <% item.likes.each do |like| %>
  <li> <%= link_to(like.user.username, like.user) %></li>
<% end %>
</ul>
<br>
<br>
<% else %>
    <%= link_to 'Login/SignUp', new_user_session_path %>
<% end %>
<% @items.each do |item| %>
    <%= image_tag item.avatar.url(:medium), class: "block" %>
    <div>
        <%= render partial: "likes", locals: {item: item} %></span><%= item.likes_count %>
    </div>
<% end %>

Items.rb

class Item < ApplicationRecord
    has_many :likes, :counter_cache => true
    belongs_to :user
    has_attached_file :avatar, styles: { medium: "300x300>", thumb: "100x100>" }, default_url: "/images/:style/missing.png"
    validates_attachment_content_type :avatar, content_type: /\Aimage\/.*\z/
end

User.rb

class User < ApplicationRecord
    devise :database_authenticatable, :registerable,
       :recoverable, :rememberable, :trackable, :validatable, :omniauthable, omniauth_providers: [:facebook]
    has_many :likes
    has_attached_file :avatar, styles: { medium: "300x300>", thumb: "100x100>" }, default_url: "/images/:style/missing.png"
    validates_attachment_content_type :avatar, content_type: /\Aimage\/.*\z/

    def likes?(post)
        post.likes.where(user_id: id).any?
    end
end

用户控制器

class UsersController < ApplicationController
    before_action :set_user, only: [:show, :edit, :update, :destroy, :share]
    def index
        @users = User.all
    end

    def show
        @user = User.find(params[:id])
        @items = Item.all
    end

    private

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

    def item_params
        params.require(:item).permit(:product, :amount, :city_id, :avatar)
    end
end

Like.rb

class Like < ApplicationRecord
belongs_to :item, :counter_cache => true
belongs_to :user
end

喜欢控制器

class Items::LikesController < ApplicationController
before_action :authenticate_user!
before_action :set_book

def create

    @item.likes.where(user_id: current_user.id).first_or_create


    respond_to do |format|
        format.html {redirect_to @item}
        format.js
    end
end


def destroy
    @item.likes.where(user_id: current_user.id).destroy_all

    respond_to do |format|
        format.html {redirect_to @item}
        format.js
    end
end
private
def set_book
    @item = Item.find(params[:item_id])
end
end

日志

Processing by ItemsController#index as HTML

在布局/应用程序中渲染items / index.html.erb 用户负载（0.3ms）SELECT＆＃34;用户＆＃34;。* FROM＆＃34;用户＆＃34;用户＆＃34;。＆＃34; id＆＃34; =？ ORDER BY＆＃34;用户＆＃34;。＆＃34; id＆＃34; ASC限制？ [[＆＃34; id＆＃34;，1]，[＆＃34; LIMIT＆＃34;，1]] 项目负载（0.3ms）SELECT＆＃34; items＆＃34;。* FROM＆＃34; items＆＃34; ORDER BY created_at DESC 在layouts / application中呈现items / index.html.erb（287.6ms）在313ms完成500内部服务器错误（ActiveRecord：0.6ms）

ActionView :: Template :: Error（未定义的局部变量或方法`item＆＃39; for＃＆lt;＃：0x007f9afbfd14f0＆gt; 你的意思是？ item_url items_url item_path @items）： 5：
6：＆lt;％= link_to current_user.username，current_user，class：＆＃34; profile-style＆＃34; ％GT; 7：

＆lt;％= link_to（like.user.username，like.user）％＆gt;

app / views / items / index.html.erb：8：在`_app_views_items_index_html_erb ___ 2312434021832006771_70151814680620＆＃39; 在救援/布局中渲染/usr/local/lib/ruby/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/template_error.html.erb 渲染/usr/local/lib/ruby/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_source.html.erb 呈现/usr/local/lib/ruby/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_source.html.erb(8.3ms）渲染/usr/local/lib/ruby/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb 呈现/usr/local/lib/ruby/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb(3.3ms）渲染/usr/local/lib/ruby/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb 呈现/usr/local/lib/ruby/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb(1.2ms）在救援/布局（94.4ms）内呈现/usr/local/lib/ruby/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/template_error.html.erb

Answer 1

在items/index.html.erb中，您在第9行引用了@item.likes.each，但实例变量@item尚未在items_controller#index中设置。您只定义了@items，因此您收到的关于nil未回复#likes的错误。

如果你想看到所有项目的喜欢，有很多方法可以通过Arel实现这一目标。

Answer 2

您还需要一个表（模型）“喜欢”和关联has-many-through。像这样：

class Item
  has_many :likes
  has_many :users, through: :likes
end

class Like
  belongs_to :user
  belongs_to :item
end

class User
  has_many :likes
  has_many :items
  has_many :liked_items, through: :likes
end

Answer 3

这是一个简单的错误。我认为问题在于您的偏见..您使用locals调用部分内容，并在模板代码中使用@item代替item，{{1} }}不是item变量。

instance

当您使用<% @items.each do |item| %> <%= image_tag item.avatar.url(:medium), class: "block" %> <div> <%= render partial: "likes", locals: {item: item} %></span><%= item.likes_count %> </div> <% end %>渲染部分内容时，您需要将本地变量用作普通变量，而不是locals个变量。

这应该有用。

instance

如何显示所有喜欢我的帖子的用户

3 个答案: