Simple voting system in Ruby on Rails blog

Question

I'm doing some simple voting system in my blog.And I have some problems with this.I'm new in Rails.I have this for the moment.

This is my comment.rb

  include Mongoid::Document
   field :name, type: String
   field :body, type: String
   field :abusive, type: Boolean, default: false
   validates_presence_of :name, :body
   embedded_in :post, :inverse_of => :comments
   belongs_to :user
   has_many :votes, :as => :votable,:dependent => :destroy

 end

And my vote.rb

class Vote
include Mongoid::Document
include Mongoid::Timestamps

field :vote_up 
field :vote_down 
belongs_to :user
belongs_to :comment 
end

in my comment controller i have something like this

def vote_up
@post = Post.find(params[:post_id])
comment = @post.comments.find(params[:id])
  if @comment
   comment.votes.exists?(:user_id => current_user.id)
   @notice2 = 'You already voted'
  else
    @vote_up = comment.votes.create(:user_id => current_user.id, :votable_id => 1)
    redirect_to @post,  :method => :post
  end
end

def vote_down
 @post = Post.find(params[:post_id])
 comment = @post.comments.find(params[:id])
 negative_count = comment.votes.find_all { |c| c.vote_down == true} .count
 if negative_count >= 3 
  #here i would like to add,that comment after 3 negative votes is abusive 


end

and in my view

- if @post.comments.size > 0
 %h2 Comments
 - @post.comments.each do |comment|
  %h3= comment.name
  %p= comment.body  

   %i.icon-black.icon-thumbs-up  
   = link_to "vote_up", vote_up_post_comment_path(@post.id, comment.id), :method => :post


 %i.icon-black.icon-thumbs-down

 = link_to "vote_down", vote_down_post_comment_path(@post.id, comment.id), :method => :post

I don't know how to make this work,really.thank you for any tips.