Rails3,GridFS,MongoID,CarrierWave实现图片上传

最近准备将Everyday CMS的数据存储由MySQL切换到MongoDB,作为实验先探探路，看看能不能用MongoDB的GridFS来存储图片，下面具体的实现：

首先环境准备：Rails 3.1.3/Ruby 1.9.2p320/MongoDB 已经安装并启动.

创建app

$ rails new demo

修改Gemfile文件，加入如下Gems

gem 'mongoid' #2.4.10
gem 'bson_ext' #1.6.2
gem 'carrierwave' #0.5.8
gem 'carrierwave-mongoid', :require => 'carrierwave/mongoid' #0.1.7
gem 'mini_magick' #3.4

生成mongoid.yml

$ rails g mongoid:config

通过修改 config/application.rb去掉对默认数据库依赖

require 'rails/all'
require "action_controller/railtie"
require "action_mailer/railtie"
require "active_resource/railtie"
require "rails/test_unit/railtie"

继续添加以下代码，防止 error mongoid not found 的问题

config.generators do |g|
  g.orm :active_record
end

删除默认的 config/database.yml，并用scaffold创建blog应用:

$ rm -f config/database.yml
$ rails g scaffold blog name:string content:text

添加carrierwave配置文件 config/initializers/carrierwave.rb

CarrierWave.configure do |config|
  config.storage = :grid_fs
  config.grid_fs_access_url = ""
  config.grid_fs_database = Mongoid.database.name
  config.grid_fs_host = Mongoid.config.master.connection.host
end

生成File Uploader

$ rails g uploader File

修改app/uploaders/file_uploader.rb

class FileUploader < CarrierWave::Uploader::Base
  include CarrierWave::MiniMagick
  # Choose what kind of storage to use for this uploader:
  storage :grid_fs
  # Override the directory where uploaded files will be stored.
  def store_dir
	"uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end
  def default_url
	 "/uploads/fallback/" + [version_name, "default.png"].compact.join('_')
  end
  # Create different versions of your uploaded files:
  version :thumb do
	 process :resize_to_fill=> [50, 50]
  end
  version :normal do
	 process :resize_to_fill => [150, 200]
  end
  version :big do
	 process :resize_to_fill => [250, 300]
  end
  version :large do
	 process :resize_to_fill => [350, 400]
  end
  def extension_white_list
	 %w(jpg jpeg gif png)
  end
  def filename
	 "something.jpg" if original_filename
  end
end

生成生成gridfs的controller

$ rails g controller gridfs

修改GridfsController,内容如下

class GridfsController < ActionController::Metal
  def serve
	gridfs_path = env["PATH_INFO"].gsub("/uploads/", "uploads/")
	begin
	  puts "---------------------------------------"
	  puts gridfs_path
	  puts Mongoid.database.name
	  puts "---------------------------------------"
	  gridfs_file = Mongo::GridFileSystem.new(Mongoid.database).open(gridfs_path, 'r')
	  self.response_body = gridfs_file.read
	  self.content_type = gridfs_file.content_type
	rescue Exception => e
	  self.status = :file_not_found
	  Rails.logger.debug { "#{e}" }
	  self.content_type = 'text/plain'
	  self.response_body = ''
	  raise e
	end
  end
end

修改routes.rb，使开发模式下，通过gridfs这个controller来管理图片文件

if Rails.env.development?
  match "/uploads/*path" => "gridfs#serve"
end

修改app/models/blog.rb，添加file字段，并挂载uploader, 注意这里不再继承active record.

class Blog
 include Mongoid::Document
   field :name
   field :content
   field :file
   mount_uploader :file, FileUploader
end

修改app/views/blogs/_form.html.erb，在content表单项下面添加图片上传

<%= f.label :file %>
<%= f.file_field :file %>

修改 app/views/blogs/index.html.erb, 用来展现上传的图片

<%= blog.file.size %>
<%= blog.file.filename%>
<%= image_tag blog.file_url(:thumb)%>
<%= image_tag blog.file_url(:normal)%>
<%= image_tag blog.file_url(:big)%>
<%= image_tag blog.file_url(:large)%>

到这里终于可以启动服务，上传图片了，看看结果

carrierwave-mogoid

再看mongodb的查询结果，多了三个collection以及对于的储存记录

mogo-result

注意:尽量不要在rails3.1以下版本操作，否则会出现无法集成mongoid的问题，OK JSUT DO IT!

401 Words 24 May 2012 Suzhou, China