http://rorwiki.hellopen.net/index.php?title=HowtosFiles

图片上传是web应用程序中常用到的，ROR中是如何实现的。

1.创建一个表
create table pictures(
 id int not null auto_increment,
 comment varchar(100),
 name varchar(200),
 content_type varchar(100),
 data blob,
 primary key(id)
);

2.建立一个controller

class UploadController < ApplicationController
 
 def get
  @picture = Picture
 end
 
end

3.页面get.rhtml
<%=error_messages_for("picture")%>
<%=form_tag({:action=>"save",:multipart=>true})%>
 comment:<%=text_field("picture","comment")%><br>
 Upload your picture:<%=file_field("picture","picture")%><br>
 <%=submit_tag("Upload file")%>

<%=end_form_tag%>
在这边要注意的是要设置:multipart=>true.

4.建立实体Picture.rb
class Picture < ActiveRecord::Base
 validates_format_of(:content_type,:with=>/^image/,
      :message=>"---you can only upload pictures")
      
 def picture=(picture_field)
  self.name = base_part_of(picture_field.original_filename)
  self.content_type = picture_file.content_type.chomp
  self.data = picture_field.read
 end
 
 def base_part_of(file_name)
  name = File.basename(file_name)
  name.gsub(/[^\w._-]/,'')
 end

end

5.在controller增加一个save方法

def save
 @picture = Picture.new(params[:picture])
 if @picture.save
  redirect_to(:action=>"show",:id=>@picture)
 else
  render(:action=>:get)
 end
end
这样就把图片存入到数据库中了。那如何在页面上现实图片呢？

6.在controllers中增加一个picture的方法。

def picture
 @picture = Picture.find(params[:id])
 send_data(@picture.data,
     :filename=>@picture.name,
     :type=>@picture.content_type,
     :disposition>"inline")
end

转到显示页面的action就很简单了。

def show
 @picture = Picture.find(params[:id])
end

7.显示图片页面show.rhtml

<h3><%=@picture.comment%></h3>
<image src="<%=url_for(:action=>"picture",:id=>@picture.id)%>"/>