NoMethodError：类调用私有方法“existence_check”

Question

我有一个很奇怪的问题。

场景：我正在使用 MongoDB（mongoid gem）在 Rails 中收集照片，其中每张照片都属于一个相册。一些 mongo 字段由关注点提供，并且模型被正确命名。 所以，

关注：MediaConcerns::Base

module MediaConcerns
  module Base
    extend ActiveSupport::Concern

    included do
      field :photo_description, type: String
    end
  end
end

关注：MediaCollectionConcerns::Base

module MediaCollectionConcerns
  module Base
    extend ActiveSupport::Concern

    included do
      field :album_title, type: String
      field :album_description, type: String
    end
  end
end

而MediaType::Photo 是：

module MediaType
  class Photo
    include Mongoid::Document
    include Mongoid::Timestamps::Short
    include MediaConcerns::Base

    embedded_in :photo_album, class_name: 'MediaCollection::PhotoAlbum'    
  end
end

而MediaCollection::PhotoAlbum 是：

module MediaCollection
  class PhotoAlbum
    include Mongoid::Document
    include Mongoid::Timestamps::Short
    include MediaCollectionConcerns::Base

    embeds_many :photos, class_name: 'MediaType::Photo'
  end
end

不管有没有顾虑，问题依然存在，并且与embedded_in和embeds_many有关。

通过 Rails 控制台，当我尝试 MediaCollection::PhotoAlbum.new 时，它给出：

NoMethodError: private method `existence_check' called for MediaCollection::PhotoAlbum:Class
from /home/marco/.rvm/gems/ruby-2.4.0/gems/mongoid-6.1.0/lib/mongoid/relations/macros.rb:355:in `relate'
from /home/marco/.rvm/gems/ruby-2.4.0/gems/mongoid-6.1.0/lib/mongoid/relations/macros.rb:85:in `embeds_many'
from /home/marco/workspace/backend/app/models/media_collection/photo_album.rb:10:in `<class:PhotoAlbum>'
from /home/marco/workspace/backend/app/models/media_collection/photo_album.rb:2:in `<module:MediaCollection>'
from /home/marco/workspace/backend/app/models/media_collection/photo_album.rb:1:in `<top (required)>'

MediaType::Photo.new 也是如此：

NoMethodError: private method `existence_check' called for MediaType::Photo:Class
from /home/marco/.rvm/gems/ruby-2.4.0/gems/mongoid-6.1.0/lib/mongoid/relations/macros.rb:355:in `relate'
from /home/marco/.rvm/gems/ruby-2.4.0/gems/mongoid-6.1.0/lib/mongoid/relations/macros.rb:56:in `embedded_in'
from /home/marco/workspace/backend/app/models/media_type/photo.rb:15:in `<class:Photo>'
from /home/marco/workspace/backend/app/models/media_type/photo.rb:2:in `<module:MediaType>'
from /home/marco/workspace/backend/app/models/media_type/photo.rb:1:in `<top (required)>'

有什么问题？如果我删除（仅用于调试）关系embeds_many 和embedded_in，问题就解决了，但我需要嵌入这些文档！

也许 Rails 找不到 :photos，但我已经按照 mongoid 文档的建议指定了 class_name: 'MediaType::Photo'，并且为 'MediaCollection::PhotoAlbum' 指定了同样的内容

我需要帮助。谢谢。

Answer 1

我终于找到了原因但没有解决，是gem上的一个bug。

在这里阅读：github issue