Question

我为铁轨编写了一个宝石，有一个小型的mongoid购物车。

通过包含include MongoidCart::ActsAsProduct

实现的模型

class MyProduct
   include Mongoid::Document

   include MongoidCart::ActsAsProduct
end


module MongoidCart
  class CartItem
    include Mongoid::Document

    belongs_to :mongoid_cart_cart, :class_name => 'MongoidCart::Cart'
  end
end


module MongoidCart
  class Cart
    include Mongoid::Document

    field :user_id, type: String

    has_many :cart_items, :inverse_of => :cart, :class_name => 'MongoidCart::CartItem'
    belongs_to :customer, :inverse_of => :carts, :class_name => MongoidCart.configuration.customer_model_name

  end
end

将class_name - Product课程CartItem引入MongoidCart::CartItem课程，我遇到了麻烦。它应该自动添加:my_product类的关系。当我＆＃34;硬编码＆＃34;作为:the_class_to_point_to_as_symbol我有，没有错误。

如何使`module MongoidCart module ActsAsProduct extend ActiveSupport::Concern included do #adds dynamic association to the CartItem to refer to the ActsAsProduct class MongoidCart::CartItem.class_eval( 'belongs_to :the_class_to_point_to_as_symbol, :class_name => "Product", inverse_of: :cart_item' ) end end end`动态？

# provision
config.vm.provision :shell, inline: <<-SHELL
  # Set up sudo
  echo 'vagrant ALL=(ALL) NOPASSWD: ALL' > /etc/sudoers.d/vagrant
  chmod 0440 /etc/sudoers.d/vagrant
  # Setup sudo to allow no-password for "sudo" commands
  usermod -a -G sudo vagrant
SHELL

Answer 1

我最后创建了一个生成String的新类，它由class_eval解释并在范围之外调用它们并将字符串放在变量中：

module MongoidCart
  module ActsAsProduct
    extend ActiveSupport::Concern

    included do

      # adds dynamic association to the CartItem to refer to the ActsAsProduct class
      relation_method = MongoidCart::Relation.build_product_relation_string(name)
      MongoidCart::CartItem.class_eval(relation_method)
  end
end



module MongoidCart
  class Relation

    # creates a string which can be implemented in models to provide dynamcic relation
    def self.build_product_relation_string(class_name)
      "belongs_to "+ ":#{class_name.to_s.underscore.to_sym}" + ", :class_name => '#{class_name.constantize}', inverse_of: :cart_item"
    end

  end
end

Answer 2

self块内的

included{}是包含的类，因此您可以执行类似

的操作

included do
  MongoidCart::CartItem.add_product_relation(self)
end

MongoidCart :: CartItem：

def self.add_product_relation cls
  belongs_to cls.name.to_s.underscore.to_sym, class_name:cls, inverse_of: :cart_item
end

Rails关注动态关系

2 个答案: