Golang - Cannot access map in []interface{} - json

Question

I have used json.Unmarshal and extracted json content. I then managed to get one layer deeper into the []interface{} by using the following code:
response, err := http.Get("http://api.steampowered.com/ISteamUser/GetPlayerSummaries/v0002/?key=2B2A0C37AC20B5DC2234E579A2ABB11C&steamids=76561198132612090")
content, err := ioutil.ReadAll(response.Body)
defer response.Body.Close()
if err != nil {
panic(0)
}
var decoded map[string]interface{}
if err := json.Unmarshal(content, &decoded); err != nil {
panic(0)
}
players := decoded["response"].(map[string]interface{})["players"]
if err != nil {
panic(0)
}
Variable players' type is []interface {} and content is [map[personaname:Acidic]].
How do I access this map? I've tried players["personaname"] but that doesn't seem to work. Any ideas?

Answer 1

Defining a struct type with the expected schema will make your life easier when you want to get the data from it:
package main
import "fmt"
//import "net/http"
//import "io/ioutil"
import "encoding/json"
// you don't need to define everything, only what you need
type Player struct {
Steamid string
Communityvisibilitystate int
Personaname string
Lastlogoff int64 // time.Unix(Lastlogoff, 0)
Profileurl string
Avatar string
Avatarmedium string
Avatarfull string
Personastate int
Realname string
Primaryclanid string
Timecreated int64 // time.Unix(Timecreated, 0)
Personastateflags int
//Loccountrycode string // e.g. if you don't need this
}
func main() {
/*response, err := http.Get("http://api.steampowered.com/ISteamUser/GetPlayerSummaries/v0002/?key=2B2A0C37AC20B5DC2234E579A2ABB11C&steamids=76561198132612090")
if err != nil {
panic(err)
}
content, err := ioutil.ReadAll(response.Body)
defer response.Body.Close()
if err != nil {
panic(0)
}*/
content := []byte(`{
"response": {
"players": [
{
"steamid": "76561198132612090",
"communityvisibilitystate": 3,
"profilestate": 1,
"personaname": "Acidic",
"lastlogoff": 1459489924,
"profileurl": "http://steamcommunity.com/id/ari9/",
"avatar": "https://steamcdn-a.akamaihd.net/steamcommunity/public/images/avatars/bc/bc50a4065c31c606e51dfad329341b2d1f1ac4d3.jpg",
"avatarmedium": "https://steamcdn-a.akamaihd.net/steamcommunity/public/images/avatars/bc/bc50a4065c31c606e51dfad329341b2d1f1ac4d3_medium.jpg",
"avatarfull": "https://steamcdn-a.akamaihd.net/steamcommunity/public/images/avatars/bc/bc50a4065c31c606e51dfad329341b2d1f1ac4d3_full.jpg",
"personastate": 3,
"realname": "Ari Seyhun",
"primaryclanid": "103582791440552060",
"timecreated": 1397199406,
"personastateflags": 0,
"loccountrycode": "TR"
}
]
}
}`)
var decoded struct {
Response struct {
Players []Player
}
}
if err := json.Unmarshal(content, &decoded); err != nil {
panic(err)
}
fmt.Printf("%#v\n", decoded.Response.Players)
}
http://play.golang.org/p/gVPRwLFunF
You can also create a new named type from time.Time for Timecreated and Lastlogoff with its own UnmarshalJSON function, and immediately convert it to time.Time using time.Unix()

Answer 2

Players is a JSON array. Thus you have to convert it to a slice of interface.
Then you can access any element of the slice and casting it to a map[string]interface{} type.
Here's the working example
package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
)
func main() {
response, err := http.Get("http://api.steampowered.com/ISteamUser/GetPlayerSummaries/v0002/?key=2B2A0C37AC20B5DC2234E579A2ABB11C&steamids=76561198132612090")
content, err := ioutil.ReadAll(response.Body)
defer response.Body.Close()
if err != nil {
panic(0)
}
var decoded map[string]interface{}
if err := json.Unmarshal(content, &decoded); err != nil {
panic(0)
}
players := decoded["response"].(map[string]interface{})["players"]
if err != nil {
panic(0)
}
sliceOfPlayers := players.([]interface{})
fmt.Println((sliceOfPlayers[0].(map[string]interface{}))["personaname"])
}