小编mis*_*ker的帖子

在我尝试拥有一个活动模型的Rails 3.2.11和"开发"环境中:

class DisponibilityApi
  include ActiveModel::Model

  attr_accessor :start_time, :end_time 
  validates :start_time, :end_time, :presence => true

end

我有一个错误:

NameError:未初始化的常量ActiveModel :: Model

但是当我手动包含它时:

class DisponibilityApi
  extend  ActiveModel::Naming
  extend  ActiveModel::Translation
  include ActiveModel::Validations
  include ActiveModel::Conversion

  attr_accessor :start_time, :end_time 
  validates :start_time, :end_time, :presence => true

end

现在它有效!

我错过了什么吗？

谢谢 !