Question

如果用户有'消息'

，我正试图展示一些内容

视图/消息/ index.html.erb

<% if @user.messages.any? %>
You have messages!
<% else %>
Sorry, you have no messages
<% end %>

控制器/ messages_controller.rb

class MessagesController < ApplicationController

def index
    @user = current_user
    @messages = @user.messages
end

当我实现此代码时，即使用户没有消息（由rails console确认：

    user = User.find(1)
user.messages.any?
=> false

消息'你有消息！'仍然出现

还要考虑添加身份验证使用设计 gem

Answer 1

<% if @user.messages.any? %>
  <%= "User with id #{@user.id} has messages" %>
<% else %>
  <%= "User with id #{@user.id} doesnt have messages" %>
<% end %>

这将显示类似的东西 User with id 5 has messages 要么 User with id 6 doesnt have messages

现在从rails控制台验证这个

User.find(5).messages.any?

Answer 2

尝试

   <% if @user.present? %>
   <%= puts "User is selected" %> 
   <% if @user.messages.present? %>
   <%= puts "User have message" %> 
   <% end %>
   <% end %>

Rails .html.erb - 如果，else语句不起作用

2 个答案: