MongoDB - 查找 - 多个集合 - 结果在一个数组中

问题描述

网站集字段 - _id,name

节点集合字段 - _id,siteId,name

设备集合字段 - _id,nodeId,name

传感器集合字段 - _id,deviceid,name

我是 MongoDB 新手，预期结果（没有重复数据）：

[{
        "_id": "608aa9bd323489617cfe2081","name": "Site One two 3","node": [{
            "name": "Node Guj 3 222 ","device": [{
                "mode": 1,"siteId": "608aa9bd323489617cfe2081","nodeId": "608aa9cc323489617cfe2083","isActive": true,"_id": "608aa9ee323489617cfe2084","sensor": [{
                    "_id": "608aa9ee323489617cfe2085","name": "NVR_Channel1"
                }]
            }]
        }]
    },{
        "_id": "608aa9bd323489617cfe2083","name": "Site One two 22","device": []
        }]
    },{
        "_id": "608aa9bd323489617cfe2085","name": "SiteO","node": [{
            "name": "Node22 ","sensor": []
            }]
        }]
    }
]

正如我之前提到的，我是 MongoDB 的新手，我尝试了以下查询，但没有得到预期的结果

const result = await Site.aggregate([
        {
          $lookup:
          {
            from: "nodes",localField: "_id",foreignField: "siteId",as: "node"
          }
        },{
          $lookup:
          {
            from: "devices",localField: "node._id",foreignField: "nodeId",as: "device"
          }
        },{
          $lookup:
          {
            from: "sensors",localField: "node.device._id",foreignField: "deviceid",as: "sensor"
          }
        }
      ]);

以下是当前响应，其中 node、device、sensor 处于同一级别，预期为站点 -> 节点 -> 设备 -> 传感器。

[{
    "_id": "608aab1016be1c11dfe77422","name": "Aivid_Site_One","node": [{
            "_id": "608b9072932b3c0cc5ab4fd0","name": "no sensort 11"
        },{
            "_id": "608b9073932b3c0cc5ab4fd1","name": "no sensort 11"
        }
    ],"device": [{
        "_id": "608b9091932b3c0cc5ab4fd2","name": "3nd floor Device"
    }],"sensor": [{
        "_id": "608b9091932b3c0cc5ab4f33","name": "sensor 1"
    }]
}]

解决方法

您可以尝试使用管道查找，

• $lookup 带有节点并将 siteId 传递给管道
• $match siteId 条件
• $lookup 和 devices 并将 deviceId 传递给管道
• $match deviceId 条件
• $lookup 与 sensors 集合

db.sites.aggregate([
  {
    $lookup: {
      from: "nodes",let: { siteId: "$_id" },pipeline: [
        { $match: { $expr: { $eq: ["$$siteId","$siteId"] } } },{
          $lookup: {
            from: "devices",let: { nodeId: "$_id" },pipeline: [
              { $match: { $expr: { $eq: ["$$nodeId","$nodeId"] } } },{
                $lookup: {
                  from: "sensors",localField: "_id",foreignField: "deviceId",as: "sensors"
                }
              }
            ],as: "devices"
          }
        }
      ],as: "nodes"
    }
  }
])

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