ruby-on-rails – Mongoid使用has_one将一个对象与同一个类的两个不同对象相关联

概述我已经看到1：N的这类问题的解决方案,但他们似乎没有读到1：1,这是使用MongoDB 1.8,Mongoid 2.0.0.rc.8,Rails 3.0.5 class Coach include Mongoid::Document field :name, :type => String belongs_to :coached, :class_name => Team, :i 我已经看到1：N的这类问题的解决方案,但他们似乎没有读到1：1,这是使用MongoDB 1.8,MongoID 2.0.0.rc.8,Rails 3.0.5

class Coach    include MongoID::document   fIEld :name,:type => String   belongs_to :coached,:class_name => Team,:inverse_of => :coach,:foreign_key => "coach_ID"   belongs_to :assisted,:inverse_of => :assist,:foreign_key => "assist_ID" end class Team   include MongoID::document   fIEld :name,:type => String   has_one :coach,:class_name => Coach,:inverse_of => :coached   has_one :assist,:inverse_of => :assisted end

然后我开始和Rails控制台会话和：

irb(main):001:0> c = Coach.new(:name => "Tom")  => #<Coach _ID: da18348d298ca47ad000001,_type: nil,_ID: BSON::ObjectID('4da18348d298ca47ad000001'),name: "Tom",coach_ID: nil,assist_ID: nil> irb(main):002:0> a = Coach.new(:name => "Dick") => #<Coach _ID: 4da18352d298ca47ad000002,_ID: BSON::ObjectID('4da18352d298ca47ad000002'),name: "Dick",assist_ID: nil> irb(main):003:0> t = Team.new(:name => "Allstars") => #<Team _ID: 4da18362d298ca47ad000003,_ID: BSON::ObjectID('4da18362d298ca47ad000003'),name: "Allstars"> irb(main):005:0> t.coach = c NoMethodError: undefined method `constantize' for Coach:Class irb(main):005:0> c.coached = t NoMethodError: undefined method `constantize' for Team:Class

任何建议将不胜感激！

解决方法 您在定义Coach时引用了类Team,但该类尚不存在.
您有两种选择：

>将class_name声明为String而不是常量,例如：class_name => ‘团队'(首选,见gist)>完全删除：class_name =>团队选项让MongoID找出参与该关联的正确类.有一点需要注意：您需要确保在类Coach之前声明类Team(加载源代码的顺序现在很重要,因此这个解决方案并不理想)

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