Ruby on rails Mongoid-在某些情况下无法设置/获取属性

我有一个简单的模型类：

class Sentence
  include Mongoid::Document
  include Mongoid::Timestamps
  field :content, :type => String
  field :num_votes, :type => Integer
  field :last_submitted, :type => Time
  field :meaning_id , :type => String
  belongs_to :word
  belongs_to :user
  attr_accessible :content,:num_votes,:last_submitted
  attr_accessor :content,:num_votes,:last_submitted
end

我正在尝试如下设置内容属性：

sen = Sentence.first
sen.content = "Hello" - This does not update the attribute(no error thrown)
sen.write_attributes(content: "hello") - This does not update the attribute(no error thrown)

但如果我这样做了

sen[:content] = "Hello" - This updates the attribute
sen.write_attribute(:content,"Hello") - This updates the attribute

我对这里发生的事情感到困惑，为什么在某些情况下，我的更新有效，而在另一些情况下则无效。我对get属性也有同样的问题。 sen.content返回nil，但sen[：content]返回正确的内容 我有另一个模型类，在本例中，上面提到的用于获取/设置属性的所有四种方法都适用于所有属性

class User
  include Mongoid::Document
  # Include default devise modules. Others available are:
  # :token_authenticatable, :confirmable,
  # :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  ## Database authenticatable
  field :email,              :type => String, :default => ""
  field :encrypted_password, :type => String, :default => ""

  validates_presence_of :email
  validates_presence_of :encrypted_password

  ## Recoverable
  field :reset_password_token,   :type => String
  field :reset_password_sent_at, :type => Time

  ## Rememberable
  field :remember_created_at, :type => Time

  ## Trackable
  field :sign_in_count,      :type => Integer, :default => 0
  field :current_sign_in_at, :type => Time
  field :last_sign_in_at,    :type => Time
  field :current_sign_in_ip, :type => String
  field :last_sign_in_ip,    :type => String

  ## Confirmable
  # field :confirmation_token,   :type => String
  # field :confirmed_at,         :type => Time
  # field :confirmation_sent_at, :type => Time
  # field :unconfirmed_email,    :type => String # Only if using reconfirmable

  ## Lockable
  # field :failed_attempts, :type => Integer, :default => 0 # Only if lock strategy is :failed_attempts
  # field :unlock_token,    :type => String # Only if unlock strategy is :email or :both
  # field :locked_at,       :type => Time

  ## Token authenticatable
  # field :authentication_token, :type => String
  include Mongoid::Timestamps

  field :name, type: String
  validates :name, presence: true
  VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  validates :email, presence: true, format: { with: VALID_EMAIL_REGEX }
  index({ email: 1 }, { unique: true, name: "email_index" })
  field :rank, type: String
  field :num_words, type: Integer
  field :time_in_city, type: Time
  field :last_logged_in, type: Time
  field :points, type: Integer
  has_many :sentences

  attr_accessible :name, :email, :password, :password_confirmation, :remember_me

end

有人能帮我一下，告诉我为什么get/set在某些情况下有效，而在其他情况下无效？ 我是 使用mongo（1.7.0） 使用mongoid（2.5.0）

---

使用rails（3.2.8）

尝试删除

attr\u访问器：content、：num\u vots、：last\u submitted

。

attr\u accessor

方法用于创建方法，以便简单地设置和读取对象中的实例变量。例如，对于

attr\u accessor:content

，您将得到以下方法：

def content= (something)
    @content = something
end

def content
    @content
end

---

第一个不涉及更新数据库的

save

调用，只涉及对内存中实例变量的更新。

为什么同时有

字段：content

、

attr\u accessible:content

和

attr\u accessor:content

？