MongoDB/Mongoose 一对多，在子节点中引用父节点 - 分组并加入

Posted 2023-03-11

【中文标题】MongoDB/Mongoose 一对多，在子节点中引用父节点 - 分组并加入

【英文标题】：MongoDB/Mongoose One-to-Many with refence to parent in child - group and join

【发布时间】：2017-09-04 14:22:07

【问题描述】：

我按照 Mongo 文档中的建议在子集合中引用父子集合的父子集合，因为子集合有增长的前景。 https://docs.mongodb.com/manual/tutorial/model-referenced-one-to-many-relationships-between-documents/

发布者（父）集合：

   _id: "oreilly",
   name: "O'Reilly Media",
   founded: 1980,
   location: "CA"

书籍（儿童）收藏 - 参考其中的出版商：

   _id: 123456789,
   title: "MongoDB: The Definitive Guide",
   author: [ "Kristina Chodorow", "Mike Dirolf" ],
   published_date: ISODate("2010-09-24"),
   pages: 216,
   language: "English",
   publisher_id: "oreilly"
,
   _id: 234567890,
   title: "50 Tips and Tricks for MongoDB Developer",
   author: "Kristina Chodorow",
   published_date: ISODate("2011-05-06"),
   pages: 68,
   language: "English",
   publisher_id: "oreilly"

现在我想要实现的是让所有出版商拥有他们的书籍子数组：

    
  "_id": "oreilly",
  "name": "O'Reilly Media",
  "founded": 1980,
  "location": "CA",
  "books": [
    
      "_id": 123456789,
      "title": "MongoDB: The Definitive Guide",
      "author": [
        "Kristina Chodorow",
        "Mike Dirolf"
      ],
      "published_date": "2010-09-24",
      "pages": 216,
      "language": "English",
      "publisher_id": "oreilly"
    ,
    
      "_id": 234567890,
      "title": "50 Tips and Tricks for MongoDB Developer",
      "author": "Kristina Chodorow",
      "published_date": "2011-05-06",
      "pages": 68,
      "language": "English",
      "publisher_id": "oreilly"
    
  ]

我使用 Mongoose，并且我知道如果我在出版商中存储了一系列书籍参考资料，我可以完成 .populate("books") - 我不想这样做，因为书籍会不断增加。我想知道如何在图书收藏中存在出版商参考资料的情况下获得相同的结果。

【参考方案1】：

您必须使用$lookup 来执行连接。

db.publisher.aggregate([$lookup: from: 'books', localField: '_id', foreignField: 'publisher_id', as: 'books' ]).pretty()

        "_id" : "oreilly",
        "name" : "O'Reilly Media",
        "founded" : 1980,
        "location" : "CA",
        "books" : [
                
                        "_id" : 123456789,
                        "title" : "MongoDB: The Definitive Guide",
                        "author" : [
                                "Kristina Chodorow",
                                "Mike Dirolf"
                        ],
                        "published_date" : ISODate("2010-09-24T00:00:00Z"),
                        "pages" : 216,
                        "language" : "English",
                        "publisher_id" : "oreilly"
                ,
                
                        "_id" : 234567890,
                        "title" : "50 Tips and Tricks for MongoDB Developer",
                        "author" : "Kristina Chodorow",
                        "published_date" : ISODate("2011-05-06T00:00:00Z"),
                        "pages" : 68,
                        "language" : "English",
                        "publisher_id" : "oreilly"
                
        ]