So I attempted to build what I asked about in this question: Fix voting mechanism

However, this solution doesn't work. A user can still vote however many times he or she wants. How could I fix this and/or refactor?

def create       
    @video = Video.find(params[:video_id])
    @vote = @video.video_votes.new
    @vote.user = current_user

    if params[:type] == "up"
      @vote.value = 1
    else
      @vote.value = -1
    end

  if @previous_vote.nil?
    if @vote.save
      respond_to do |format|
        format.html { redirect_to @video }
        format.js
      end
    else
      respond_to do |format|
        format.html { redirect_to @video }
        format.js {render 'fail_create.js.erb'}
      end
    end
  elsif @previous_vote.value == params[:type]
    @previous_vote.destroy
  else
    @previous_vote.destroy    
    if @vote.save
      respond_to do |format|
        format.html { redirect_to @video }
        format.js
      end
    else
      respond_to do |format|
        format.html { redirect_to @video }
        format.js {render 'fail_create.js.erb'}
      end
    end
  end
  @previous_vote = VideoVote.where(:video_id => params[:video_id], :user_id => current_user.id).first
end