英文:
Golang print map inside map generated by json.NewDecoder
问题
我正在使用这里的答案从API中获取一些JSON数据：
package main
import (
"encoding/json"
"fmt"
"log"
"net/http"
)
func main() {
resp, err := http.Get("http://api.openweathermap.org/data/2.5/forecast?id=524901&appid=1234")
if err != nil {
log.Fatal(err)
}
var generic map[string]interface{}
err = json.NewDecoder(resp.Body).Decode(&generic)
if err != nil {
log.Fatal(err)
}
fmt.Println(generic)
}
它可以工作，我有一个存储在generic变量中的JSON映射。
当我使用以下代码打印时：
fmt.Println(generic["city"])
我得到以下结果：
map[id:524901 name:Moscow coord:map[lon:37.615555 lat:55.75222] country:RU population:0 sys:map[population:0]]
现在我想访问城市名称。我尝试了以下代码：
fmt.Println(generic["city"]["name"])
但是我得到了错误：
muxTest/router.go:30: invalid operation: generic["city"]["name"] (type interface {} does not support indexing)
我还尝试了generic["city"].name，但没有成功。
如何访问城市名称的值？
英文:
I'm using the answer here to fetch some json from an api:
package main
import (
"encoding/json"
"fmt"
"log"
"net/http"
)
func main() {
resp, err := http.Get("http://api.openweathermap.org/data/2.5/forecast?id=524901&appid=1234")
if err != nil {
log.Fatal(err)
}
var generic map[string]interface{}
err = json.NewDecoder(resp.Body).Decode(&generic)
if err != nil {
log.Fatal(err)
}
fmt.Println(generic)
}
It's working, I have a map of the json stored in the generic variable.
When I print with:
fmt.Println(generic["city"])
I get back:
map[id:524901 name:Moscow coord:map[lon:37.615555 lat:55.75222] country:RU population:0 sys:map[population:0]]
Now I want to access the city name. I'm trying the following:
fmt.Println(generic["city"]["name"])
And I get error:
> muxTest/router.go:30: invalid operation: generic["city"]["name"] (type
> interface {} does not support indexing)
Also tried generic["city"].name which didn't work.
How can I access the city name value?
答案1
得分: 1
你需要将map[string]interface{}的interface{}转换为更有用的类型。在这种情况下，再次转换为map[string]interface{}，因为city本身就是一个map。你无法将其转换为其他类型，因为coord也是一个map，所以无法将city转换为map[string]string。
链接：https://play.golang.org/p/bGsYLnSAK4
英文:
You need to cast the interface{} of your map[string]interface{} to something more useful. In this case a map[string]interface{} again since city is itself a map. You can't convert it to anything else because the coord is a map too, so converting city to a map[string]string isn't possible.
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