json - Golang check if interface type is nil -

when unmarshaling string of json using golang's json.unmarshal() function, unmarshal string map[string]interface{}. i not sure weather there more optimal way of decoding json.

to point, json unmarshal's type nil, not string (or int etc.). throws panic saying "interface conversion: interface nil, not int". how can avoid panic or check if interface's type nil or not?

here example of problem in action: https://play.golang.org/p/0atzxbbdos

check key exist instead of letting panic.

func keyexists(decoded map[string]interface{}, key string) {     val, ok := decoded[key]     return ok && val != nil }  func main() {  jsontext := `{         "name": "jimmy",         "age":  23     }`      var decoded map[string]interface{}      if err := json.unmarshal([]byte(jsontext), &decoded); err != nil {         fmt.println(err)         os.exit(0)     }      if keyexists(decoded, "name") {         fmt.println(decoded["name"].(string))     }     if keyexists(decoded, "age") {         fmt.println(decoded["age"].(float64))     }     if keyexists(decoded, "gender") {         fmt.println(decoded["gender"].(int))     } } 

also, far being optimal if know json like. specified in documentation, can unmarshal directly struct:

type human struct {     name string     age int     gender int }  func main() {     jsontext := `{         "name": "jimmy",         "age":  23     }`      decoded := human{}      if err := json.unmarshal([]byte(jsontext), &decoded); err != nil {         fmt.println(err)         os.exit(0)     }      fmt.println(decoded.name)     fmt.println(decoded.age)     fmt.println(decoded.gender) }