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:使用MongoDB时有一个关系问题

mongomapper mongodb stack ruby ruby-on-rails

marcgg · 技术社区 · 16 年前

我有一个非常简单的设置。总而言之,我正在做的是:

class Movie
  include MongoMapper::Document
  has_one :setting
end

class Setting
  include MongoMapper::EmbeddedDocument
  belongs_to :movie
end

我要做的是以与电影相同的格式更新电影的设置其他信息。因此,我这样做:

- form_for ['movies', @movie] do |f|
  # ...
  -f.fields_for @movie.setting do |ms|
    # ...

当我收到此错误时,这不起作用:

stack level too deep

[以下文字重复一百次左右]

/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/associations/one_proxy.rb:46:in `find_target'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/associations/proxy.rb:98:in `load_target'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/associations/proxy.rb:88:in `method_missing'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/associations/one_proxy.rb:56:in `target_class'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/associations/one_proxy.rb:46:in `find_target'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/associations/proxy.rb:98:in `load_target'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/associations/one_proxy.rb:17:in `replace'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/associations.rb:39:in `setting='
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/embedded_document.rb:185:in `send'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/embedded_document.rb:185:in `initialize'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/embedded_document.rb:177:in `each'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/embedded_document.rb:177:in `initialize'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/dirty.rb:42:in `initialize'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/embedded_document.rb:91:in `new'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/embedded_document.rb:91:in `initialize_doc'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/document.rb:316:in `find_one'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/document.rb:321:in `find_one!'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/document.rb:88:in `find!'
/Users/marc/.gem/ruby/1.8/gems/mongo_mapper-0.6.10/lib/mongo_mapper/document.rb:96:in `find'
/Users/marc/Code/mycompany/dontreadthat/sources/app/controllers/application_controller.rb:53:in `set_page_title'

以下是要点:当我用电影模型中的一个键替换has-one关系时:

key :setting, Setting

…它很好用。没有堆栈错误。

我可以放下关系,用钥匙走,但是:

它不漂亮
如果我尝试使用.update_属性更新movie.setting,它会删除所有其他属性。假设我更新movie.setting.key1,它将重置movie.setting.key2…这是正常的

我在外面找不到任何有用的东西,所以任何帮助或指点都会非常感谢。

2 回复 | 直到 16 年前

Kyle Banker 16 年前

我很确定,has-one关系不支持作为嵌入文档。例如,这个做工作:

class Setting
  include MongoMapper::Document
  key :movie_id, ObjectId
  belongs_to :movie
end

class Movie
  include MongoMapper::Document
  one :setting, :class => Setting
end

如果您不需要第一类设置文档(可能不需要),可以考虑使用哈希类型的键或为Mongo定义的某个自定义类型的另一个键来存储这些设置。有关示例,请参见MongoMapper测试套件中的Windowsize类。

marcgg 16 年前

我最终将设置设置为键并重载=方法:

电影中

  def setting=(new_setting)
    super ( (self.setting.nil?)? new_setting : (self.setting.keys.merge new_setting) )
  end

在设置中

  def keys
    keys_hash = {}
    self.attributes.each do |attribute|
      keys_hash.merge!( {attribute[0].to_s => attribute[1].to_s}) unless attribute[0].to_s == "_id"
    end
    return keys_hash
  end

这不是最佳的,但在有更好的方法做有一段关系之前,它会很好地工作。