当我尝试将使用POST方法发送的数据分配给对象时，我收到以下错误。
Started POST "/backend/photos" for 127.0.0.1 at 2012-02-10 19:24:48 +0100
Processing by Backend::PhotosController#create as */*
Parameters: {"utf8"=>"✓", "authenticity_token"=>"yeFZOu6sG3tyNqT4uBb5Xq0fp+1yTZ2wxn0WFPvGhPw=", "photo"=>{"source_type"=>"post", "source_id"=>"5", "cropping"=>"1", "img"=>#<ActionDispatch::Http::UploadedFile:0x00000004798020 @original_filename="p028.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"photo[img]\"; filename=\"p028.jpg\"\r\nContent-Type: image/jpeg\r\n", @tempfile=#<File:/tmp/RackMultipart20120210-27534-1yyq97g>>}}
Completed 500 Internal Server Error in 1ms
NoMethodError (undefined method `new' for nil:NilClass):
app/controllers/backend/photos_controller.rb:5:in `new'
app/controllers/backend/photos_controller.rb:5:in `create'
Rendered /usr/local/rvm/gems/ruby-1.9.2-p290/gems/actionpack-3.2.1/lib/action_dispatch/middleware/templates/rescues/_trace.erb (2.6ms)
Rendered /usr/local/rvm/gems/ruby-1.9.2-p290/gems/actionpack-3.2.1/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (1.0ms)
Rendered /usr/local/rvm/gems/ruby-1.9.2-p290/gems/actionpack-3.2.1/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (5.3ms)
在控制器中：
# -*- encoding : utf-8 -*-
class Backend::PhotosController < Backend::BaseController
def create
@photo = Photo.new(params[:photo])
if @photo.save
render :json => { :pic_path => @photo.img.url.to_s , :name => @photo.img.instance.attributes["img_file_name"] }, :content_type => 'text/html'
else
#todo handle error
render :json => { :result => 'error'}, :content_type => 'text/html'
end
end
模特：
# -*- encoding : utf-8 -*-
class Photo < ActiveRecord::Base
scope :previous, lambda {|p| where("id < ? ", p.id).order(" id desc ").limit(1) }
scope :next, lambda {|p| where("id > ? ", p.id).order(" id asc ").limit(1) }
after_save :observe_seq_after_save
before_create :set_seq_before_create
after_update :change_seq_after_update
after_destroy :change_seq_after_destroy
attr_accessor :cropping
belongs_to :product
after_update :reprocess_picture, :if => :cropping?
has_attached_file :img, :styles => {
:thumb => { :geometry => '130x130#', :quality => 60, :format => 'JPG', :processors => [:cropper]},
:normal => { :geometry => '520x520>', :quality => 90, :format => 'JPG'},
:big => { :geometry => '800x600>', :quality => 90, :format => 'JPG'}
}
validates_attachment_presence :img
validates_attachment_size :img, :less_than => 5.megabytes
validates_attachment_content_type :img, :content_type => [ 'image/jpeg', 'image/png', 'image/pjpeg' ]
在路线中：
namespace :backend do
root :to => "dashboards#show"
match "/set_per_page_admin" => "sessions#set_per_page_admin"
match "/posts/:post_id/photos/:id/move_up" => "photos#move_up"
match "/posts/:post_id/photos/:id/move_down" => "photos#move_down"
match "/photos/reset_seq" => "photos#reset_seq"
match "/photos/new/:source_type/:source_id" => "photos#new"
resources :photos do
member do
get :crop
get :crop_existing_photo
end
end
scope "/remote" do
match "/show_pic" => "photos#show_pic"
match "/show_crop" => "photos#show_crop"
end
resources :posts
end
已安装的宝石：
Gems included by the bundle:
* actionmailer (3.2.1)
* actionpack (3.2.1)
* activemodel (3.2.1)
* activerecord (3.2.1)
* activeresource (3.2.1)
* activesupport (3.2.1)
* arel (3.0.0)
* builder (3.0.0)
* bundler (1.0.21)
* cocaine (0.2.1)
* coffee-rails (3.2.2)
* coffee-script (2.2.0)
* coffee-script-source (1.2.0)
* date_validator (0.6.3)
* erubis (2.7.0)
* execjs (1.3.0)
* foreigner (1.1.1)
* hike (1.2.1)
* i18n (0.6.0)
* journey (1.0.1)
* jquery-rails (2.0.0)
* json (1.6.5)
* libv8 (3.3.10.4)
* magic_encoding (0.0.2)
* mail (2.4.1)
* mime-types (1.17.2)
* multi_json (1.0.4)
* mysql2 (0.3.11)
* paperclip (2.6.0 71d3f46)
* polyglot (0.3.3)
* rack (1.4.1)
* rack-cache (1.1)
* rack-ssl (1.3.2)
* rack-test (0.6.1)
* rails (3.2.1)
* railties (3.2.1)
* rake (0.9.2.2)
* rdoc (3.12)
* rmagick (2.12.0)
* sass (3.1.15)
* sass-rails (3.2.4)
* sprockets (2.1.2)
* stringex (1.3.0)
* therubyracer (0.9.9)
* thor (0.14.6)
* tilt (1.3.3)
* treetop (1.4.10)
* tzinfo (0.3.31)
* uglifier (1.2.3)
* will_paginate (3.0.3)
有趣的是，在另一个项目中，相同的代码运行良好。这个项目中的宝石：
* actionmailer (3.1.0.rc8)
* actionpack (3.1.0.rc8)
* activemodel (3.1.0.rc8)
* activerecord (3.1.0.rc8)
* activeresource (3.1.0.rc8)
* activesupport (3.1.0.rc8)
* addressable (2.2.6)
* arel (2.2.1)
* authlogic (3.1.0)
* aws-s3 (0.6.2)
* bcrypt-ruby (3.0.1)
* builder (3.0.0)
* bundler (1.0.21)
* date_validator (0.6.3)
* devise (1.5.3)
* erubis (2.7.0)
* execjs (1.3.0)
* foreigner (1.1.1)
* heroku (2.18.1)
* hike (1.2.1)
* i18n (0.6.0)
* jquery-rails (1.0.19)
* json (1.6.5)
* launchy (2.0.5)
* libv8 (3.3.10.4)
* magic_encoding (0.0.2)
* mail (2.3.0)
* mime-types (1.17.2)
* multi_json (1.0.4)
* mysql2 (0.3.11)
* nifty-generators (0.4.6)
* orm_adapter (0.0.6)
* paperclip (2.3.6)
* polyglot (0.3.3)
* rack (1.3.3)
* rack-cache (1.0.3)
* rack-mount (0.8.3)
* rack-ssl (1.3.2)
* rack-test (0.6.1)
* rails (3.1.0.rc8)
* rails-i18n (0.3.0)
* rails3-jquery-autocomplete (1.0.5)
* railties (3.1.0.rc8)
* rake (0.9.2.2)
* rdoc (3.12)
* rest-client (1.6.7)
* rmagick (2.12.0)
* rubyzip (0.9.5)
* sprockets (2.0.3)
* stringex (1.3.0)
* term-ansicolor (1.0.7)
* therubyracer (0.9.9)
* thor (0.14.6)
* tilt (1.3.3)
* treetop (1.4.10)
* tzinfo (0.3.31)
* uglifier (1.2.2)
* warden (1.1.0)
* will_paginate (3.0.2)
* xml-simple (1.1.1)
我添加了一个宝石'aws-sdk'，但它没有任何帮助。 迁移文件：
class CreatePhotos < ActiveRecord::Migration
def self.up
create_table :photos do |t|
t.string :source_type, :null => true
t.integer :source_id, :null => true
t.integer :seq
t.string :img_file_name
t.string :img_content_type
t.integer :img_file_size
t.datetime :img_updated_at
t.string :title, :null => true
t.text :desc, :limit=>400, :null=>true
t.string :meta_title, :default => nil
t.string :meta_desc, :default => nil
t.string :meta_keywords, :default => nil
t.timestamps
end
add_index(:photos, :source_id)
add_index(:photos, :source_type)
add_index(:photos, :seq)
end
def self.down
drop_table :photos
end
end
我没有想法解决这个问题。谢谢你的帮助