rails 上传图片

ruby 代码

class CreatePictures < ActiveRecord::Migration
  def self.up
    create_table :pictures do |t|
    t.column :comment, :string, :limit=>100
    t.column :name, :string, :limit=>200
    t.column :content_type, :string, :limit=>100
    t.column :title, :binary
    end
  end

  def self.down
    drop_table :pictures
  end
end

ruby 代码

class RenameColumnData < ActiveRecord::Migration
  def self.up
  rename_column :pictures,:title, :data
  end

  def self.down
  rename_column :pictures,:data, :title
  end
end

以上是通过migration建立相应的数据表。

 

建立controller：

ruby 代码

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

 

 

建立get template：

ruby 代码

<%= error_messages_for("picture") %>
<%= form_tag({:action => 'save'}, :multipart => true) %>
Comment: <%= text_field("picture", "comment") %>

Upload your picture: <%= file_field("picture", "picture") %>

<%= submit_tag("Upload file") %>
<%= end_form_tag %>

建立model：

ruby 代码

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_field.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

 

扩充controller，添加save action：

ruby 代码

def save
  @picture = Picture.new(params[:picture])
  if @picture.save

    redirect_to(:action => 'show', :id => @picture.id)
  else
    render(:action => :get)
  end
end

 

扩充controller，添加picture action：

ruby 代码

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

 

 

定义show action:

ruby 代码

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

 

 

 

显示图片：

ruby 代码

 <%= @picture.comment %>

 

 注：引自Dave Thomas的《Agile Web Development with Rails》