取mongoid中结果的并集

Question

我有两个mongoid文档Class1和Class2，它们都有subject字段，现在我可以从单个类中按主题分组得到结果，如下所示

@class1_subject = Class1.all.group_by {|s| s.subject }

@class2_subject = Class2.all.group_by {|s| s.subject }

现在@class1_subject包含了=>

{
  "algebra" => [
    #<Class1 _id: 51af35f4066104e046000003, name: "root", subject: "algebra">
  ],
  "algebra-II" => [
    #<Class1 _id: 51af3da0066104f448000003, name: "roo2", subject: "algebra-II">
  ]
}

@class2_subject包含=>

{
  "algebra" => [
    #<Class2 _id: 51af07d606610423e7000002,.........,subject: "algebra">
  ]
}

在联合之后，我期待着这个结果

{
  "algebra" => [
    #<Class1 _id: 51af35f4066104e046000003,name: "root", subject: "algebra">,
    #<Class2 _id: 51af07d606610423e7000002,.........,subject: "algebra">
  ],
  "algebra-II" => [
    #<Class1 _id: 51af3da0066104f448000003, name: "roo2", subject: "algebra-II">
   ]
}

我该怎么做呢？？

Answer 1

这可以是一个近似值：

@class1_subject.keys.each do |key|
  @class2_subject[key] ||= []
  @class2_subject[key] += @class1_subject[key]
end  

@class2_subject现在有了结果