SDK数据库 Aggregate·从近到远输出
Aggregate.geoNear(options: Object): Aggregate
支持端：小程序 2.7.4, 云函数 0.8.1, Web
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 | 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
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"
}
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
}