如何在rails控制器中设置html类属性？

我是铁杆初学者.我在通知控制器中使用after_action.
通知控制器

class NotificationsController < ApplicationController

    layout "posts"

    after_action :read_message, only: [:index]

    def index
        @notifications = Notification.where(:recipient_id => session[:registered_id]).order("created_at DESC")

    end

    def new
        @user = User.find(session[:user_id])
        @notification = @user.notifications.new
    end

    def create
        @user = User.find(session[:user_id])
        @notification = @user.notifications.new notification_params
        if @notification.save
            redirect_to(:controller => "posts", :action => "index")
        else
            render "new"
        end
    end

    private

    def notification_params
        params.require(:notification).permit(:message, :user_id, :recipient_id, :status)
    end

    def read_message
        @notifications = Notification.where(:recipient_id => session[:registered_id]).order("created_at DESC")
        @notifications.read_all
    end

end

通知#index视图

 <% @notifications.each do |notification| %>
   

    
<%= notification.message %>
    
from <%= notification.user.registered_id %>
  
 <% end %>

现在在控制器的after_action方法中,我想将