我有一个疼痛的定位器应用程序,它将显示300米提供的纬度和经度值的所有商店。 商店文档包含活动时间和地理位置。
我想首先获取所有商店,然后说200米处有4家商店。所以这4家商店根据他们最后的活跃时间排序。
基本上,mysql的样子是按距离asc排序, last_active desc
我的go代码如下:
package main
import (
"encoding/json"
"fmt"
"gopkg.in/mgo.v2"
"gopkg.in/mgo.v2/bson"
"log"
)
type Store struct {
ID string `bson:"_id,omitempty" json:"shopid"`
Name string `bson:"name" json:"name"`
Location GeoJson `bson:"location" json:"location"`
Time time.Time `bson:"time" json:"time"`
}
type GeoJson struct {
Type string `json:"-"`
Coordinates []float64 `json:"coordinates"`
}
func main() {
cluster := "localhost" // mongodb host
// connect to mongo
session, err := mgo.Dial(cluster)
if err != nil {
log.Fatal("could not connect to db: ", err)
panic(err)
}
defer session.Close()
session.SetMode(mgo.Monotonic, true)
// search criteria
long := 39.6910592
lat := 35.6909623
scope := 3000 // max distance in metres
var results []Store // to hold the results
// query the database
c := session.DB("test").C("stores")
// insert
man := Store{}
man.ID = "1"
man.Name = "vinka medical store"
man.Location.Type = "Point"
man.Location.Coordinates = []float64{lat, long}
// insert
err = c.Insert(man)
fmt.Printf("%v\n", man)
if err != nil {
fmt.Println("There is insert error")
panic(err)
}
// ensure
// Creating the indexes
index := mgo.Index{
Key: []string{"$2dsphere:location"},
Bits: 26,
}
err = c.EnsureIndex(index)
if err != nil {
fmt.Println("There is index error")
panic(err)
}
//find
err = c.Find(bson.M{
"location": bson.M{
"$nearSphere": bson.M{
"$geometry": bson.M{
"type": "Point",
"coordinates": []float64{long, lat},
},
"$maxDistance": scope,
},
},
}).All(&results)
//err = c.Find(bson.M{"_id": "1"}).All(&results)
if err != nil {
panic(err)
}
//convert it to JSON so it can be displayed
formatter := json.MarshalIndent
response, err := formatter(results, " ", " ")
fmt.Println(string(response))
}
我应该如何修改此部分?
//find
err = c.Find(bson.M{
"location": bson.M{
"$nearSphere": bson.M{
"$geometry": bson.M{
"type": "Point",
"coordinates": []float64{long, lat},
},
"$maxDistance": scope,
},
},
}).All(&results)