Mongoid and carrierwave

问题:

In order to remain DRY, I have a class ModelBase that includes Mongoid document as follows:

class ModelBase
  include Mongoid::Document

  alias_attribute :guid, :id

  def as_json(options = {})
    azove_hash = options.merge(:methods => :guid)
    super azove_hash
  end
end

then all my models inherit from ModelBase and they seem to be working fine. However, there is one model where I use CarrierWave. when it inherits from ModelBase, the call to mount_uploader fails. And when I include the model inside with no subclassing it works fine. Isn't it possible to use carrierwave in a class that inherits from another class?

Here is the version of the class that is failing. would appreciate any suggestion/idea

require 'carrierwave/orm/mongoid'

class SomeOtherModel < ModelBase
  field :abstract
  validates :abstract, :presence => true

  field :category
  validates :category, :presence => true, :inclusion => {:in => %w{audio graphics text video}}

  field :content_uri
  validates :content_uri, :presence => true

  has_and_belongs_to_many :topics
  has_and_belongs_to_many :events
  has_and_belongs_to_many :authors, :class_name => "User"

  mount_uploader :content, ContentUploader

  attr_accessible :abstract, :category, :content, :content_uri, :authors, :topics, :events   
end

回答1:

I think you're making things too complicated. I see no need to inherit from modelbase with a mongoid document. Mongoid itself doesn't use inheritance, and simply includes modules as needed.

So if you have a set of fields re-used, such as contact information, just do something like:

class Customer
  include Mongoid::Document
  include DataModules::ContactDocument
  mounts_uploader :logo, LogoUploader
end

class User
  inclue Mongoid::Document
  include DataModules::ContactDocument
end

Then include the code that you want to reuse in /lib/data_modules/contact_document.rb

module DataModules::ContactDocument

  def self.included(receiver) 
    receiver.class_eval do
      field :email, :type=>String
      ...
      validates_existence_of :email
    end
  end
end