_haikus.html.erb

<div class="haiku">
  <%= simple_format haiku.content %>
  <em>
    -- <%= haiku.user.name %>
  | <%= pluralize haiku.reputation_for(:votes).to_i, "vote" %>
	| <%= link_to "up", vote_haiku_path(haiku, type: "up"), method: "post" %>
	| <%= link_to "down", vote_haiku_path(haiku, type: "down"), method: "post" %>
	
  </em>
</div>

ERROR MSG

Routing Error

No route matches [GET] "/haikus/1/vote"

Try running rake routes for more information on available routes. 

haikus.rb

class Haiku < ActiveRecord::Base
  attr_accessible :content

  belongs_to :user
  
  has_reputation :votes, source: :user, aggregated_by: :sum
end

haikus_controller.rb

class HaikusController < ApplicationController
  before_filter :authorize, except: [:index, :show]

  def index
    @haikus = Haiku.all
  end

  def show
    @haiku = Haiku.find(params[:id])
  end

  def create
    @haiku = current_user.haikus.create!(params[:haiku])
    redirect_to @haiku, notice: "Successfully created haiku."
  end
  
  def vote
    value = params[:type] == "up" ? 1 : -1
    @haiku = Haiku.find(params[:id])
    @haiku.add_or_update_evaluation(:votes, value, current_user)
    redirect_to :back, notice: "Thank you for voting"
  end
end

routes.rb

Youhaiku::Application.routes.draw do
  get 'signup', to: 'users#new', as: 'signup'
  get 'login', to: 'sessions#new', as: 'login'
  get 'logout', to: 'sessions#destroy', as: 'logout'

  resources :users
  resources :sessions
  resources :haikus do
    member { post :vote }
  end

  root to: 'haikus#index'
end