# [Aggregate](Aggregate).geoNear(options: Object): [Aggregate](Aggregate)

> 支持端：[小程序 2.7.4](/miniprogram/dev/framework/client-lib/version.md), [云函数 0.8.1](/minigame/dev/wxcloud/reference/changelog-server-sdk), [Web](/minigame/dev/wxcloud/reference/changelog-web-sdk)

聚合阶段。将记录按照离给定点从近到远输出。

## 参数

### options: Object

| 属性 | 类型 | 默认值 | 必填 | 说明 |
| ---- | ---- | ------ | -------- | ---- |
| near | [GeoPoint](/minigame/dev/wxcloud/reference-sdk-api/database/geo/GeoPoint) |  | 是 | GeoJSON Point，用于判断距离的点 |
| spherical | true |  | 是 | 必填，值为 true |
| limit | number |  | 否 | 限制返回记录数 |
| maxDistance | number |  | 否 | 距离最大值 |
| minDistance | number |  | 否 | 距离最小值 |
| query | Object |  | 否 | 要求记录必须同时满足该条件（语法同 where） |
| distanceMultiplier | number |  | 否 | 返回时在距离上乘以该数字 |
| distanceField | string |  | 是 | 存放距离的输出字段名，可以用点表示法表示一个嵌套字段 |
| includeLocs | string |  | 否 | 列出要用于距离计算的字段，如果记录中有多个字段都是地理位置时有用 |
| key | string |  | 否 | 选择要用的地理位置索引。如果集合由多个地理位置索引，则必须指定一个，指定的方式是指定对应的字段 |

## 返回值

### [Aggregate](Aggregate)

## API 说明

- `geoNear` 必须为第一个聚合阶段
- 必须有地理位置索引。如果有多个，必须用 `key` 参数指定要使用的索引。

## 示例

假设集合 `attractions` 有如下记录：

```
{
  "_id": "geoNear.0",
  "city": "Guangzhou",
  "docType": "geoNear",
  "location": {
    "type": "Point",
    "coordinates": [
      113.30593,
      23.1361155
    ]
  },
  "name": "Canton Tower"
},
{
  "_id": "geoNear.1",
  "city": "Guangzhou",
  "docType": "geoNear",
  "location": {
    "type": "Point",
    "coordinates": [
      113.306789,
      23.1564721
    ]
  },
  "name": "Baiyun Mountain"
},
{
  "_id": "geoNear.2",
  "city": "Beijing",
  "docType": "geoNear",
  "location": {
    "type": "Point",
    "coordinates": [
      116.3949659,
      39.9163447
    ]
  },
  "name": "The Palace Museum"
},
{
  "_id": "geoNear.3",
  "city": "Beijing",
  "docType": "geoNear",
  "location": {
    "type": "Point",
    "coordinates": [
      116.2328567,
      40.242373
    ]
  },
  "name": "Great Wall"
}
```

```js
const $ = db.command.aggregate
db.collection('attractions').aggregate()
  .geoNear({
    distanceField: 'distance', // 输出的每个记录中 distance 即是与给定点的距离
    spherical: true,
    near: db.Geo.Point(113.3089506, 23.0968251),
    query: {
      docType: 'geoNear',
    },
    key: 'location', // 若只有 location 一个地理位置索引的字段，则不需填
    includeLocs: 'location', // 若只有 location 一个是地理位置，则不需填
  })
  .end()
```

返回结果如下：

```
{
  "_id": "geoNear.0",
  "location": {
    "type": "Point",
    "coordinates": [
      113.30593,
      23.1361155
    ]
  },
  "docType": "geoNear",
  "name": "Canton Tower",
  "city": "Guangzhou",
  "distance": 4384.68131486958
},
{
  "_id": "geoNear.1",
  "city": "Guangzhou",
  "location": {
    "type": "Point",
    "coordinates": [
      113.306789,
      23.1564721
    ]
  },
  "docType": "geoNear",
  "name": "Baiyun Mountain",
  "distance": 6643.521654040738
},
{
  "_id": "geoNear.2",
  "docType": "geoNear",
  "name": "The Palace Museum",
  "city": "Beijing",
  "location": {
    "coordinates": [
      116.3949659,
      39.9163447
    ],
    "type": "Point"
  },
  "distance": 1894750.4414538583
},
{
  "_id": "geoNear.3",
  "docType": "geoNear",
  "name": "Great Wall",
  "city": "Beijing",
  "location": {
    "type": "Point",
    "coordinates": [
      116.2328567,
      40.242373
    ]
  },
  "distance": 1928300.3308822548
}
```