Question

我正在使用Mongo Mapper而我正在试图弄清楚如何制作文档。例如，我想做这样的事情：

class Question
  include MongoMapper::Document

  many :answers
end

class Answer
  include MongoMapper::Document

  belongs_to :question, :required => true
end

但是当我这样做时，并没有强制说答案有问题：

> Answer.new.save
 => true

Answer 1

MongoMapper包含ActiveModel :: Validations，因此您可以像活动记录一样使用验证。以下应该有效：

class Question
  include MongoMapper::Document

  many :answers
end

class Answer
  include MongoMapper::Document

  belongs_to :question

  validates :question, :presence => true
end

您可以在此处查看rails文档以获取有关这些验证的更多信息：http://api.rubyonrails.org/classes/ActiveModel/Validations/ClassMethods.html#method-i-validates

Answer 2

一些回调怎么办？

class Answer
  include MongoMapper::Document

  belongs_to :question

  def before_save
    # if question is nil, return false (this cancels save)
    return false unless question
    true
  end
end

你如何使用mongo mapper制作belongs_to？

2 个答案: