Ruby on rails 3 多态关联的回形针自定义路径和url

我使用依恋模型作为多态关联。如何根据关联更改路径和url参数

附着模型

class Attachment < ActiveRecord::Base
  belongs_to :user
  belongs_to :attachable, :polymorphic => true

  has_attached_file :attachment,
                    :url  => "/attachments/:id/:basename.:extension",
                    :path => ":rails_root/public/attachments/:id/:basename.:extension",
                    :default_url => "/attachments/original/no-file.txt"
end

但是我需要基于关联来保存文件，比如，如何将参数传递给“path”attachable_type'定义上载文件所属的关联

/attachments/project/
/attachments/client/

你可以用。插值允许您调用方法来确定路径部分的值

class Attachment < ActiveRecord::Base
  belongs_to :user
  belongs_to :attachable, :polymorphic => true

  Paperclip.interpolates :attached_to do |attachment, style|
    attachment.instance.attachable.class.to_s.downcase
  end

  has_attached_file :attachment,
                    :url  => "/attachments/:id/:basename.:extension",
                    :path => ":rails_root/public/attachments/:attached_to/:id/:basename.:extension",
                    :default_url => "/attachments/original/no-file.txt"
end

类附件true
回形针.内插：附加|附加，样式|
attachment.instance.attachable.class.to_.downcase
结束
已附加文件：附件，
：url=>“/attachments/：id/：basename.：extension”，
：path=>“：rails\u root/public/attachments/：attached\u to/：id/：basename.：extension”，
：default_url=>“/attachments/original/no file.txt”
结束

您可以使用。插值允许您调用方法来确定路径部分的值

class Attachment < ActiveRecord::Base
  belongs_to :user
  belongs_to :attachable, :polymorphic => true

  Paperclip.interpolates :attached_to do |attachment, style|
    attachment.instance.attachable.class.to_s.downcase
  end

  has_attached_file :attachment,
                    :url  => "/attachments/:id/:basename.:extension",
                    :path => ":rails_root/public/attachments/:attached_to/:id/:basename.:extension",
                    :default_url => "/attachments/original/no-file.txt"
end

类附件true
回形针.内插：附加|附加，样式|
attachment.instance.attachable.class.to_.downcase
结束
已附加文件：附件，
：url=>“/attachments/：id/：basename.：extension”，
：path=>“：rails\u root/public/attachments/：attached\u to/：id/：basename.：extension”，
：default_url=>“/attachments/original/no file.txt”
结束

/attachments/project/
/attachments/client/

class Attachment < ActiveRecord::Base
  belongs_to :user
  belongs_to :attachable, :polymorphic => true

  Paperclip.interpolates :attached_to do |attachment, style|
    attachment.instance.attachable.class.to_s.downcase
  end

  has_attached_file :attachment,
                    :url  => "/attachments/:id/:basename.:extension",
                    :path => ":rails_root/public/attachments/:attached_to/:id/:basename.:extension",
                    :default_url => "/attachments/original/no-file.txt"
end

has_attached_file :attachment, :path => ":rails_root/public/attachments/#{lambda { |a| a.instance.images_path? ? 'project' : 'client' }}/:id/:basename.:extension"



def images_path?
    if your pretty condition  
      #return true
    else
      #return false 
    end
  end