从API的json响应中检索数据
我试图通过将json响应中的数据存储在一些结构(Airport+坐标)中来获取数据,但我不知道如何处理这些数据,因为我对映射和接口不够精通。代码未显示任何错误,但MapofAirports完全为空。代码如下:从API的json响应中检索数据,json,api,go,interface,maps,Json,Api,Go,Interface,Maps,我试图通过将json响应中的数据存储在一些结构(Airport+坐标)中来获取数据,但我不知道如何处理这些数据,因为我对映射和接口不够精通。代码未显示任何错误,但MapofAirports完全为空。代码如下: package main import ( //"api/client" //"api/client/clienterrors" //"api/client/openstreetmap" "encoding/json" "fmt" "io/
package main
import (
//"api/client"
//"api/client/clienterrors"
//"api/client/openstreetmap"
"encoding/json"
"fmt"
"io/ioutil"
"log"
"math"
"net/http"
"os"
"strconv"
"strings"
)
type Coordinates struct {
Longitude string `json:"lon"`
Latitude string `json:"lat"`
}
type Airport struct {
Co Coordinates `json:"location"`
IATACode string `json:"id"`
Distance float64 `json:"distance"` // distance to coordinates in kilometer
}
func GetCoordinatesFromURL(url string) (float64, float64) {
parts := strings.Split(url, "=")
lat0 := strings.Split(parts[2], "&")
lon0 := strings.Split(parts[3], "&")
lat1, _ := strconv.ParseFloat(lat0[0], 64)
lon1, _ := strconv.ParseFloat(lon0[0], 64)
return lat1, lon1
}
func CalcDistance(lat1 float64, long1 float64, lat2 float64, long2 float64) float64 {
var latitude1 = lat1 * math.Pi / 180
var latitude2 = lat2 * math.Pi / 180
var longitude1 = long1 * math.Pi / 180
var longitude2 = long2 * math.Pi / 180
var R = 6371.0
var d = R * math.Acos(math.Cos(latitude1)*math.Cos(latitude2)*math.Cos(longitude2-longitude1)+math.Sin(latitude1)*math.Sin(latitude2))
return d
}
func main() {
var Locations []Airport
Locations = make([]Airport, 0)
var url = fmt.Sprintf("https://api.skypicker.com/locations?type=radius&lat=40.730610&lon=-73.935242&radius=250&location_types=airport&limit=3&sort=id&active_only=true")
UrlLat, UrlLon := GetCoordinatesFromURL(url)
resp, err := http.Get(url)
if err != nil {
panic(err.Error())
}
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
var airportsJsonResponse interface{}
err = json.Unmarshal(body, &airportsJsonResponse)
MapofAirports, ok := airportsJsonResponse.([]interface{})
if ok {
lenAiroMap := len(MapofAirports)
locationsMaps := make(map[int]map[string]interface{})
for i := 0; i < lenAiroMap; i++ {
locationsMaps[i] = MapofAirports[i].(map[string]interface{})
}
var coords Coordinates
for i := 0; i < lenAiroMap; i++ {
if longitude, ok0 := locationsMaps[i]["lon"].(string); ok0 {
if latitude, ok1 := locationsMaps[i]["lat"].(string); ok1 {
coords = Coordinates{longitude, latitude}
}
}
code := locationsMaps[i]["id"].(string)
latFromCoordinates, _ := strconv.ParseFloat(Locations[i].Co.Latitude, 64)
lonFromCoordinates, _ := strconv.ParseFloat(Locations[i].Co.Longitude, 64)
dist := CalcDistance(latFromCoordinates, lonFromCoordinates, UrlLat, UrlLon)
Locations = append(Locations, Airport{
Co: coords,
IATACode: code,
Distance: dist,
})
}
}
LocationsJson, err := json.Marshal(Locations)
if err != nil {
log.Fatal("Cannot encode to JSON ", err)
}
fmt.Fprintf(os.Stdout, "%s", LocationsJson)
}
将此行
mapofairport,ok:=airportsJsonResponse。([]接口{})
更改为此
MapofAirports, ok := airportsJsonResponse.(map[string]interface{})
如果在这一行放置断点,您将看到airportsJsonResponse
的类型是map[string]接口{}
。
您必须将这些行更改为键值迭代
for i := 0; i < lenAiroMap; i++ {
locationsMaps[i] = MapofAirports[i].(map[string]interface{})
}
这是我最后一次更新,在运行程序时,它在解组步骤中陷入恐慌
package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"math"
"net/http"
"strconv"
"strings"
)
type Coordinates struct {
Longitude string `json:"lon"`
Latitude string `json:"lat"`
}
type Airport struct {
Co Coordinates `json:"location"`
IATACode string `json:"id"`
Distance float64 `json:"distance"` // distance to coordinates in kilometer
}
type Response struct {
Locations []Airport `json:"locations"`
// add all the other fields you care about
}
func GetCoordinatesFromURL(url string) (float64, float64) {
parts := strings.Split(url, "=")
lat0 := strings.Split(parts[2], "&")
lon0 := strings.Split(parts[3], "&")
lat1, _ := strconv.ParseFloat(lat0[0], 64)
lon1, _ := strconv.ParseFloat(lon0[0], 64)
return lat1, lon1
}
func CalcDistance(lat1 float64, long1 float64, lat2 float64, long2 float64) float64 {
var latitude1 = lat1 * math.Pi / 180
var latitude2 = lat2 * math.Pi / 180
var longitude1 = long1 * math.Pi / 180
var longitude2 = long2 * math.Pi / 180
var R = 6371.0
var d = R * math.Acos(math.Cos(latitude1)*math.Cos(latitude2)*math.Cos(longitude2-longitude1)+math.Sin(latitude1)*math.Sin(latitude2))
return d
}
func main() {
var url = fmt.Sprintf("https://api.skypicker.com/locations?type=radius&lat=40.730610&lon=-73.935242&radius=250&location_types=airport&limit=3&sort=id&active_only=true")
UrlLat, UrlLon := GetCoordinatesFromURL(url)
resp, err := http.Get(url)
if err != nil {
panic(err.Error())
}
defer resp.Body.Close()
data, err := ioutil.ReadAll(resp.Body)
res := &Response{}
if err := json.Unmarshal(data, res); err != nil {
panic(err)
}
fmt.Println(res.Locations)
for i, item := range res.Locations {
latt,_ := strconv.ParseFloat(item.Co.Latitude, 64)
lonn,_ :=strconv.ParseFloat(item.Co.Longitude, 64)
res.Locations[i].Distance = CalcDistance(latt,lonn , UrlLat, UrlLon)
}
fmt.Println("after calculate distance")
fmt.Println(res.Locations)
}
这有什么不对?如果您预先知道JSON结构,并且愿意使用Go结构,那么就不要使用映射和空接口。如果数据结构已知,我还建议使用structs进行编译。您可以。@mkopriva谢谢您的回答,它真的很有效,但我仍然只有一个问题,如果我想向结构添加#Distance float64
json:“Distance”
#,并想使用CalcDistance()函数和lon、lat参数获取值,我该怎么办?@herotet您可以让CalcDistance
成为具有坐标访问权限的类型上的方法,无论是Location
还是LocationItem
由您决定。如果需要将距离
作为一个字段,那么在完成解组后,可以通过在已解组json的结构实例上循环来计算距离,这非常简单。如果要在解组的同时计算距离,可以使用要解组的类型,实现json.Unmarshaler
接口。@herotet下面是一个解组后循环goroutine 1[运行]:main.main()C:/Users/herotet/go/src/CT_ProjectV2/main.go:70+0x536当我调试时,我得到了这样一个结果:json:cannot unmarshal number到go struct field Coordinates.locations.location.lat类型strings将lat Lon字段类型从string
更改为float64
。我还有一个问题,由于这是一项小组工作,其他人已经将纬度和经度作为字符串进行了工作,我应该如何做?我希望得到相同的结果,但在这种情况下?是否需要在坐标类型中使用字符串?或者,您是否需要在发送回发出初始请求的客户端的响应json中使用string
?
lenAiroMap := len(MapofAirports)
locationsMaps := make([]map[string]interface{},lenAiroMap)
for i, value := range MapofAirports["locations"].([]interface{}) {
converted := value.(map[string]interface{})
locationsMaps[i] = converted
}
package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"math"
"net/http"
"strconv"
"strings"
)
type Coordinates struct {
Longitude string `json:"lon"`
Latitude string `json:"lat"`
}
type Airport struct {
Co Coordinates `json:"location"`
IATACode string `json:"id"`
Distance float64 `json:"distance"` // distance to coordinates in kilometer
}
type Response struct {
Locations []Airport `json:"locations"`
// add all the other fields you care about
}
func GetCoordinatesFromURL(url string) (float64, float64) {
parts := strings.Split(url, "=")
lat0 := strings.Split(parts[2], "&")
lon0 := strings.Split(parts[3], "&")
lat1, _ := strconv.ParseFloat(lat0[0], 64)
lon1, _ := strconv.ParseFloat(lon0[0], 64)
return lat1, lon1
}
func CalcDistance(lat1 float64, long1 float64, lat2 float64, long2 float64) float64 {
var latitude1 = lat1 * math.Pi / 180
var latitude2 = lat2 * math.Pi / 180
var longitude1 = long1 * math.Pi / 180
var longitude2 = long2 * math.Pi / 180
var R = 6371.0
var d = R * math.Acos(math.Cos(latitude1)*math.Cos(latitude2)*math.Cos(longitude2-longitude1)+math.Sin(latitude1)*math.Sin(latitude2))
return d
}
func main() {
var url = fmt.Sprintf("https://api.skypicker.com/locations?type=radius&lat=40.730610&lon=-73.935242&radius=250&location_types=airport&limit=3&sort=id&active_only=true")
UrlLat, UrlLon := GetCoordinatesFromURL(url)
resp, err := http.Get(url)
if err != nil {
panic(err.Error())
}
defer resp.Body.Close()
data, err := ioutil.ReadAll(resp.Body)
res := &Response{}
if err := json.Unmarshal(data, res); err != nil {
panic(err)
}
fmt.Println(res.Locations)
for i, item := range res.Locations {
latt,_ := strconv.ParseFloat(item.Co.Latitude, 64)
lonn,_ :=strconv.ParseFloat(item.Co.Longitude, 64)
res.Locations[i].Distance = CalcDistance(latt,lonn , UrlLat, UrlLon)
}
fmt.Println("after calculate distance")
fmt.Println(res.Locations)
}