json.NewDecoder生成的地图内的Golang打印地图

Question

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?

Answer 1

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.

https://play.golang.org/p/bGsYLnSAK4