请求：Node.js+MongoDB按BlockName合并楼层数据

我是MongoDB新手，需要在Node.js与MongoDB环境下，将同一集合内的4条数据按BlockName进行聚合：把相同楼栋下不同FloorName的楼层数据整合到Floors数组中，输出指定结构。尝试多种方法未得到正确结果，寻求解决办法。

原始数据结构 #

[
  {
    BlockName: "B1",
    FloorName: "F1",
    Units: [
      {
        UnitName: 104,
        Location: [
          "Hall",
          "Living"
        ]
      }
    ]
  },
  {
    BlockName: "B1",
    FloorName: "F2",
    Units: [
      {
        UnitName: 104,
        Location: [
          "Hall",
          "Living"
        ]
      }
    ]
  },
  {
    BlockName: "B2",
    FloorName: "F1",
    Units: [
      {
        UnitName: 104,
        Location: [
          "Hall",
          "Living"
        ]
      }
    ]
  },
  {
    BlockName: "B2",
    FloorName: "F2",
    Units: [
      {
        UnitName: 104,
        Location: [
          "Hall",
          "Living"
        ]
      }
    ]
  }
]

期望输出结构 #

[
  {
    BlockName: "B1",
    Floors: [
      {
        FloorName: "F1",
        Units: [
          {
            UnitName: 104,
            Location: [
              "Hall",
              "Living"
            ]
          }
        ]
      },
      {
        FloorName: "F2",
        Units: [
          {
            UnitName: 104,
            Location: [
              "Hall",
              "Living"
            ]
          }
        ]
      }
    ]
  },
  {
    BlockName: "B2",
    Floors: [
      {
        FloorName: "F1",
        Units: [
          {
            UnitName: 104,
            Location: [
              "Hall",
              "Living"
            ]
          }
        ]
      },
      {
        FloorName: "F2",
        Units: [
          {
            UnitName: 104,
            Location: [
              "Hall",
              "Living"
            ]
          }
        ]
      }
    ]
  }
]

解决方案 #

MongoDB聚合管道实现 #

使用$group阶段按BlockName分组，通过$push将每个文档的FloorName和Units字段组合成对象，存入Floors数组：

db.yourCollectionName.aggregate([
  {
    $group: {
      _id: "$BlockName",
      Floors: {
        $push: {
          FloorName: "$FloorName",
          Units: "$Units"
        }
      }
    }
  },
  {
    $project: {
      _id: 0,
      BlockName: "$_id",
      Floors: 1
    }
  }
])

Node.js中使用原生MongoDB驱动的示例 #

const { MongoClient } = require('mongodb');

async function aggregateBlocks() {
  const uri = 'mongodb://localhost:27017'; // 替换为你的MongoDB连接字符串
  const client = new MongoClient(uri);

  try {
    await client.connect();
    const db = client.db('yourDatabaseName'); // 替换为你的数据库名
    const collection = db.collection('yourCollectionName'); // 替换为你的集合名

    const result = await collection.aggregate([
      {
        $group: {
          _id: "$BlockName",
          Floors: {
            $push: {
              FloorName: "$FloorName",
              Units: "$Units"
            }
          }
        }
      },
      {
        $project: {
          _id: 0,
          BlockName: "$_id",
          Floors: 1
        }
      }
    ]).toArray();

    console.log(JSON.stringify(result, null, 2));
  } finally {
    await client.close();
  }
}

aggregateBlocks().catch(console.error);

Node.js中使用Mongoose的示例 #

const mongoose = require('mongoose');

// 定义数据模型
const buildingSchema = new mongoose.Schema({
  BlockName: String,
  FloorName: String,
  Units: [{
    UnitName: Number,
    Location: [String]
  }]
});

const Building = mongoose.model('Building', buildingSchema);

async function aggregateBlocks() {
  await mongoose.connect('mongodb://localhost:27017/yourDatabaseName'); // 替换为你的连接字符串

  const result = await Building.aggregate([
    {
      $group: {
        _id: "$BlockName",
        Floors: {
          $push: {
            FloorName: "$FloorName",
            Units: "$Units"
          }
        }
      }
    },
    {
      $project: {
        _id: 0,
        BlockName: "$_id",
        Floors: 1
      }
    }
  ]);

  console.log(JSON.stringify(result, null, 2));
  await mongoose.disconnect();
}

aggregateBlocks().catch(console.error);

内容的提问来源于stack exchange，提问作者Prasanth