在猫鼬中按孙属性过滤

Question

我对猫鼬还很陌生，我想知道我是否可以根据孙子属性进行过滤。我到处都看过，但无法根据我正在尝试做的事情找到类似的问题。这是场景：

假设我有这样一个数据库：

db={
  "parents": [
    {
      "_id": ObjectId("5a834e000102030405000000"),
      "child": ObjectId("5a934e000102030405000000")
    },
    {
      "_id": ObjectId("5a834e000102030405000001"),
      "child": ObjectId("5a934e000102030405000001")
    },
    {
      "_id": ObjectId("5a834e000102030405000002"),
      "child": ObjectId("5a934e000102030405000002")
    },
    
  ],
  "children": [
    {
      "_id": ObjectId("5a934e000102030405000000"),
      "grandchild": ObjectId("5a734e000102030405000000")
    },
    {
      "_id": ObjectId("5a934e000102030405000001"),
      "grandchild": ObjectId("5a734e000102030405000001")
    },
    {
      "_id": ObjectId("5a934e000102030405000002"),
      "grandchild": ObjectId("5a734e000102030405000002")
    }
  ],
  "grandchildren": [
    {
      "_id": ObjectId("5a734e000102030405000000"),
      "name": "grandchild1"
    },
    {
      "_id": ObjectId("5a734e000102030405000001"),
      "name": "grandchild2"
    },
    {
      "_id": ObjectId("5a734e000102030405000002"),
      "name": "grandchild3"
    }
  ]
}

我想 return 所有 parent 有孙子名字为“grandchild1”的人。

类似于

$match: {
      "child.grandchild.name": "grandchild1"
    }

所以只有这个 parent 会在结果中 returned --

[{
  "_id": ObjectId("5a834e000102030405000000"),
  "child": ObjectId("5a934e000102030405000000")
},]

Answer 1

我在任何人回复之前就找到了答案...

https://mongoplayground.net/p/w1kw58PzCyk

db.parents.aggregate([
  {
    $lookup: {
      from: "children",
      localField: "child",
      foreignField: "_id",
      as: "child",
      
    }
  },
  {
    $addFields: {
      child: {
        $arrayElemAt: [
          "$child",
          0
        ]
      }
    }
  },
  {
    "$lookup": {
      from: "grandchildren",
      localField: "child.grandchild",
      foreignField: "_id",
      as: "grandchild",
      
    }
  },
  {
    $addFields: {
      grandchild: {
        $arrayElemAt: [
          "$grandchild",
          0
        ]
      }
    }
  },
  {
    $match: {
      "grandchild.name": "grandchild1"
    }
  }
])

在猫鼬中按孙属性过滤

Filtering By Grandchild property in mongoose

mongoose

mongodb

node.js

aggregation-framework

在猫鼬中按孙 属性 过滤

Filtering By Grandchild property in mongoose

mongoose

mongodb

node.js

aggregation-framework

在猫鼬中按孙属性过滤