Get Keys of MongoMapper Model

Suppose the following model:

class Article
  include MongoMap开发者_StackOverflow中文版per::Document

  key :name, String
  key :body, String
end

Could I get the keys of the model into an array or hash?

Article.keys will give you a hash of key names to key objects. If you just want the key names, try Article.keys.keys.

ruby-1.9.2-p0 :011 > Article.keys
 => { 
  "_id"  => #<MongoMapper::Plugins::Keys::Key:0x000001041e5d48 @type=ObjectId, @name="_id", @options={}, @default_value=nil>,
  "name" => #<MongoMapper::Plugins::Keys::Key:0x00000104013100 @type=String, @name="name", @options={}, @default_value=nil>,
  "body" => #<MongoMapper::Plugins::Keys::Key:0x00000104011b20 @type=String, @name="body", @options={}, @default_value=nil>
}
ruby-1.9.2-p0 :012 > Article.keys.keys
 => ["_id", "name", "body"]

Watch out though, if you dynamically set any keys that aren't declared in your model, or you load an object that has extra keys that aren't in your model, they will show up in the keys hash. See https://github.com/jnunemaker/mongomapper/issues/195.