Aggregate.geoNear
1. 接口描述
功能: 将记录按照离给定点从近到远输出。
声明: geoNear(options)
注意事项:
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。
2. 输入参数
参数 | 类型 | 必填 | 说明 |
---|---|---|---|
near | GeoJSON Point | 否 | 用于判断距离的点 |
spherical | boolean | 是 | 必填,值为 true |
limit | number | 是 | 限制返回记录数 |
maxDistance | number | 是 | 距离最大值 |
minDistance | number | 是 | 距离最小值 |
query | document | 是 | 要求记录必须同时满足该条件(语法同 where) |
distanceMultiplier | number | 是 | 返回时在距离上乘以该数字 |
distanceField | string | 否 | 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 | 是 | 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 | 是 | 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 |
3. 返回结果
参数 | 类型 | 必填 | 说明 |
---|---|---|---|
- | Aggregate | 是 | 聚合对象 |
4. 示例代码
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 tcb = require('@cloudbase/node-sdk')
const app = tcb.init({
env: 'xxx'
})
const db = app.database()
const $ = db.command.aggregate
const _ = db.command
exports.main = async (event, context) => {
const res = await 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()
console.log(res.data)
}
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
}