Mongodb 通过对象数组中的数据查找 $near

Question

我正在尝试使用通配符

$near

和

$geometry

从数据库文档内的现有数组中检索一个特定对象。

我有一个看起来像这样的模型：

const schema = new mongoose.Schema({
name: {...},
email: {...},
...
locations: [
    {
      name: String,
      address: String,
      mapurl: String,
      location: {
        type: {
          type: String,
          default: "Point",
        },
        coordinates: [
          {
            type: Number,
          },
        ],
      },
    },
  ],
}

像这样索引架构：

schema.index({ "locations.location": "2dsphere" });

数据库中的文档如下所示：

{
"_id": ...,
"name": ...,
"email": ...,
"locations": [
    {
      "name": "name 1",
      "address": "address 1",
      "mapurl": "https://maps.google.com/SOME_MAP_URL_1",
      "location": {
        "type": "Point",
        "coordinates": [
          11.1111,
          12.2222
        ]
      },
      "_id": {
        "$oid": "..."
      }
    },
    {
      "name": "name 2",
      "address": "address 2",
      "mapurl": "https://maps.google.com/SOME_MAP_URL_2",
      "location": {
        "type": "Point",
        "coordinates": [
          22.3333,
          23.4444
        ]
      },
      "_id": {
        "$oid": "..."
      }
    },
    {
      "name": "name 3",
      "address": "address 3",
      "mapurl": "https://maps.google.com/SOME_MAP_URL_3",
      "location": {
        "type": "Point",
        "coordinates": [
          33.4444,
          34.5555
        ]
      },
      "_id": {
        "$oid": "..."
      }
    },
  ],
}

我正在尝试在数据库中查询数组中的特定对象，然后使用

.select()

:

从该对象获取我需要的所有信息

const q = {
    _id: place._id,
    "locations.location": {
      $near: {
        $geometry: {
          type: "Point",
          coordinates: [22.333, 23.444]
        },
        $maxDistance: 100, // 100m
      },
    },
  };

  const storeCoords = await Place.find(q).select("locations.location");

结果，我期望从数组中仅获取一个距离提供的坐标近 100 米的特定对象，但相反，我得到的是整个数组，其中包含所有现有对象，包括我需要的对象。

预期结果：

{
  "coords": [
    {
      "_id": "...",
      "locations": [
        {
          "location": {
            "type": "Point",
            "coordinates": [22.3333, 23.4444]
          }
        },
      ]
    }
  ]
}

实际结果：

{
  "coords": [
    {
      "_id": "...",
      "locations": [
        {
          "location": {
            "type": "Point",
            "coordinates": [11.1111, 12.2222]
          }
        },
        {
          "location": {
            "type": "Point",
            "coordinates": [22.3333, 23.4444]
          }
        },
        {
          "location": {
            "type": "Point",
            "coordinates": [33.4444, 34.5555]
          }
        }
      ]
    }
  ]
}

我可能会以错误的方式或完全错误的通配符使用

$near

和

$geometry

。 请指教。

Answer 1

如果您只想获取一份文档，那么您应该使用 findOne。 但就您而言，它不会给您期望的答案，因为 findOne 会返回与数据库中的条件匹配的第一个文档，而该文档可能不是最近的文档。

在这种情况下，您应该使用“$geoNear”运算符。

https://www.mongodb.com/docs/manual/reference/operator/aggregation/geoNear/

这是可能有帮助的聚合

 const aggregationQuery = [
  {
    $match: {
      _id: place._id
    }
  },
  {
    $unwind: "$locations"
  },
  {
    $geoNear: {
      near: {
        type: "Point",
        coordinates: [22.333, 23.444]
      },
      distanceField: "distance",
      spherical: true,
      maxDistance: 100 // 100m
    }
  },
  {
    $limit: 1 // Limit to only the nearest location
  },
  {
    $project: {
      _id: 1,
      location: "$locations.location"
    }
  }
];

const storeCoords = await Place.aggregate(aggregationQuery);