Ruby on rails Mongodb：组合两个集合以基于其他集合中的键的值获取数据-（mongoid-rails4）

我试图通过组合bolg_post和用户文档来获得结果集

blog_post # embeds many comments doc
{ 
  "_id" : ObjectId( "55ea003e4102135d9d000677" ),
  "text" : "This is a post about natural beauties of hawaii.. blah blah..",
  "author_id": "345345026743545647567567", # references to User doc id
  "updated_at" : Date( 1441398846696 ),
  "created_at" : Date( 1441398846696 ),
  "comments" : [ 
    { "_id" : ObjectId( "55ea003e4102135d9d000002" ),
      "text" : "Very good article",
      "user_id": "83753iy45735y84934759",
      "updated_at" : Date( 1441400501867 ),
      "created_at" : Date( 1441400501867 )
    }, 
    { "_id" : ObjectId( "345a003e41026743545645454" ),
      "text" : "Hawaii is my fav",
      "user_id" : "55e7668c4102132ea8000066", # references to User doc id
      "updated_at" : Date( 1441400501867 ),
      "created_at" : Date( 1441400501867 )
    } 
  ] 
}

User # has many blog_posts

{ 
  "_id" : ObjectId( "83753iy45735y84934759" ),
  "name" : "John abc",
  "status": "active", # could be inactive, pending, deleted etc.
  "age": 29,
  "updated_at" : Date( 1441400501867 ),
  "created_at" : Date( 1441400501867 )
}

{ 
  "_id" : ObjectId( "55e7668c4102132ea8000066" ),
  "name" : "Lisa xyz",
  "status": "inactive", # could be inactive, pending, deleted etc.
  "age": 24,
  "updated_at" : Date( 1441400501867 ),
  "created_at" : Date( 1441400501867 )
}

{ 
  "_id" : ObjectId( "345345026743545647567567" ),
  "name" : "David uyi",
  "status": "active", # could be inactive, pending, deleted etc.
  "age": 39,
  "updated_at" : Date( 1441400501867 ),
  "created_at" : Date( 1441400501867 )
}

我只想获得那些博客文章，其中作者状态在用户文档中处于活动状态。 同样的，我只想得到一篇文章的评论，这些评论是由状态在用户文档中处于活动状态的用户发布的

{ 
  "blog_id" : "55ea003e4102135d9d000677",
  "text" : "This is a post about natural beauties of hawaii.. blah blah..",
  "author": {
    "author_id": "345345026743545647567567",
    "name" : "David uyi",
    "age": 39
  }
  "updated_at" : Date( 1441398846696 ),
  "created_at" : Date( 1441398846696 ),
  "comments" : [ 
    { "comment_id" : ObjectId( "55ea003e4102135d9d000002" ),
      "text" : "Very good article",
      "user" : {
        "user_id": 
        "name" : "John abc",
        "age": 29
      }
    }
    # here Lisa's comment is not shown as she is inactive
  ] 
}

但关键是我需要分页，这意味着，假设我只需要5条记录，每个查询结果限制为0，5英寸。 所以最简单的方法就是抓取前5篇博客文章文档。然后从他们那里获取用户id，然后转到用户文档并 然后查找这些用户是否处于活动状态。如果没有，则删除这些条目。但这样的话，我可能会吃不到 5结果集。那我怎么能一次完成呢。假设我有100,00,00个用户和100000个帖子。所以这将是一个糟糕的设计

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如果我按照前面提到的方式，而不是一次完成

我想你可以结合mongoid的“跳过”和“限制”方法，对给定用户的所有博客进行分页查询，跳过n*5个结果，限制为5个results@jmuet我希望它出现在一个查询中，而不是编写两个单独的查询Safaik Mongo不允许多个集合的联接；您可以查询单个集合。或者，如果“状态”字段不经常更改，那么您可以将其包括在博客文章中以及作者id中，并在用户更改状态时在所有文档中进行更新。