gistfile1.rb

Mac OS 10.9.3
Rails 4.1.0 

目前想增加一個上傳圖片給產品用的功能到網站後台

$ rails g model Photo image_name:string product:references
$ rake db:migrate
$ rails g migration add_image_to_photos image:string
$ rake db:migrate
$ rails g controller Photos

Scheme as below:

ActiveRecord::Schema.define(version: 20140612034245) do

  create_table "photos", force: true do |t|
    t.string   "image_name"
    t.integer  "product_id"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "image"
  end

config/routes.rb
Rails.application.routes.draw do
  devise_for :users
    namespace :admin do 
      resources :products do
       resources :photos
      end 
  end 
end

For new created controller, PhotosController shown below" 

class PhotosController < ApplicationController


  def create
  	@product = Product.find(params[:product_id])
 	  @photo = @product.photos.create(photo_params)
  	redirect_to admin_product_path(@product)	
  end

  private
    def photo_params
      params.require(:photo).permit(:image_name, :iamge)
    end 	
end

Finally, adding "upload photos feature" in new.html.erb

<div class="panel panel-default">
  <div class="panel-body">
    
<%= simple_form_for [:admin, @product] do|f| %>   
	<div  class="group">
		<%= f.input :title, label:'標題' %>
	</div>
	
	<div class="group">
		<%= f.input :description, label:'敘述'%>	
	</div>		

	<div class = "group">
		<%= f.input :quantity, label:'數量' %>
	</div>

	<h2>Add Photos</h2>
	<%= form_for([@product, @product.photos.build]) do |f| %>
	<% end %>
	<%= f.submit "Submit", :disable_with => 'Submiting...' %>
  </div>
</div>

<% end %>			

However, I encounter the problem I can't understand =>

  Rendered admin/products/new.html.erb within layouts/application (18.8ms)
Completed 500 Internal Server Error in 57ms

ActionView::Template::Error (undefined method `product_photos_path' for #<#<Class:0x000001013b2ef8>:0x00000101118670>):
    23: 	</div>	form_for([@article, @article.comments.build]) do |f| %>
    24: -->
    25: 	<h2>Add Photos</h2>
    26: 	<%= form_for([@product, @product.photos.build]) do |f| %>
    27: 	<% end %>
    28: 	<%= f.submit "Submit", :disable_with => 'Submiting...' %>
    29:   </div>
  app/views/admin/products/new.html.erb:26:in `block in _app_views_admin_products_new_html_erb__2984465001892677316_2165881840'
  app/views/admin/products/new.html.erb:8:in `_app_views_admin_products_new_html_erb__2984465001892677316_2165881840'

Would you mind helping me for solve the issure?