如何防止出現在index.html.erb如果條件已滿足

Question

好的一個按鈕，我有這樣的文章index.html.erb

<td><%= pluralize(article.likes.count, "like") %></td> 
<td><%= button_to '+1', "/articles/#{article.id}/user/#{current_user.id}/like_vote", method: :post %></td> 

但是，如果一個選民已經喜歡的文章，如何防止按鈕在index.html.erb中顯示？有沒有一種簡單的方法來防止在index.html.erb中顯示按鈕？

這是ArticlesController方法：

def like_vote 
    @article = Article.find(params[:id]) 
    @user_id = params[:user_id] 
    likes = Like.where("user_id = ? and article_id = ?", @user_id, @article.id) 

    if likes.blank? 
    @article.likes.create(user_id: current_user.id) 
    end 
    redirect_to(article_path) 
end 

Answer 1

Rails提供一個optimal way即scope它是一組上的數據庫交互的約束（例如，條件，限制或偏移）是chainable和reusable。

一個範圍添加到下面Like型號：

class Like < ActiveRecord::Base 
    scope :voted_count, ->(user_id, article_id) { where("user_id = ? and article_id = ?", user_id, article_id).count }  
end 

更新的觀點如下：

<td><%= pluralize(article.likes.count, "like") %></td> 
<td><%= button_to('+1', "/articles/#{article.id}/user/#{current_user.id}/like_vote", method: :post) if Like.voted_count(current_user.id, article.id) == 0 %></td> 

Answer 2

<%-unless article.voted?(current_user)%> 
<td><%= button_to '+1', "/articles/#{article.id}/user/#{current_user.id}/like_vote", method: :post %></td> 
<%- end%> 

，並作出方法在您的文章模型

def voted?(user) 
    self.likes.where(user_id:user.id).first.present? 
end 

Answer 3

你可以在你的index.html.erb ...

<td><%= pluralize(article.likes.count, "like") %></td> <td><%= button_to '+1', "/articles/#{article.id}/user/#{current_user.id}/like_vote", method: :post if article.likes.present? %></td>

只要在最後包含一個條件語句，它就會阻止它執行該行。