Question

我想将值传递给与任何字段都不相关的Mongoid模型，不应该存储在数据库中，而应该用于其他一些操作（例如执行自定义初始化）：

class Author
    include Mongoid::Document
    embeds_many :books

    field :name, type: String

    # Create a set number of empty books associated with this author.
    def create_this_many_books(quantity)
        quantity.each do |i|
            books << Book.new
        end
    end
end

class Book
    include Mongoid::Document
    embedded_in :author

    field :title, type: String
end

现在，如何在创建新作者时创建给定数量的嵌入式空book对象：

author = Author.new(name: 'Jack London', number_of_books: 41)

此处，:number_of_books不是Author模型中的字段，而是传递给create_this_many_books的值。这样做的最佳方式是什么？

Answer 1

将Author模型改为

class Author
  include Mongoid::Document
  embeds_many :books

  field :name, type: String
  attr_accessor :number_of_books 
  # this is plain old ruby class member not saved to the db but can be set and get

  after_create :create_this_many_books

  def create_this_many_books
    self.number_of_books.each do |i|
      books << Book.new
    end
  end
end

将值传递给Mongoid model.new方法而不创建字段

1 个答案: