json_parser.go

package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"log"
)

var data = `
{
	"a": {
		"b": {
			"c": {
				"d": 5
			}
		}
	}
}
`

func main() {
	var response interface{}
	if err := json.Unmarshal([]byte(data), &response); err != nil {
		log.Fatal(err)
	}
	val, err := lookup(response, "a", "b", "asdc", "d")
	if err != nil {
		println(err.Error())
		return
	}
	fmt.Printf("%#v\n", val)
}

func lookup(v interface{}, keys ...string) (interface{}, error) {
	switch len(keys) {
	case 0:
		return v, nil
	default:
		dict, ok := v.(map[string]interface{})
		if !ok {
			return nil, errors.New(fmt.Sprintf("%T is not a dictionary", v))
		}
		return lookup(dict[keys[0]], keys[1:]...)
	}
}