How do you read nested Json in Go? - json

Question

I have the following JSON to be decoded, its structure can vary therefore I do not want to use structs:
{ "cabinet": "A", "shelve": {"box": "10", "color": "red"} }
Following the Golang blog (https://blog.golang.org/json) I have prepared this program to parse it:
import (
"fmt"
"encoding/json"
)
func main() {
fmt.Println("Hello, playground")
respString := `{ "cabinet": "A", "shelve": {"box": "10", "color": "red"} }`
respBytes := []byte(respString)
var f interface{}
json.Unmarshal(respBytes, &f)
m := f.(map[string]interface{})
for k, v := range m {
switch vv := v.(type) {
case string:
fmt.Println(k, "is string", vv)
case float64:
fmt.Println(k, "is float64", vv)
case []interface{}:
fmt.Println(k, "is an array:")
for i, u := range vv {
fmt.Println(i, u)
}
default:
fmt.Println(k, "is of a type I don't know how to handle")
}
}
}
However, I am wondering how can I access the nested JSON embbedded as value in "shelve".
So far this is the output:
cabinet is string A
shelve is of a type I don't know how to handle
What shall be done to access inner key/values at shelve? Which strategy is appropriate in Go?
A complete executable code can be found in https://play.golang.org/p/AVMMVQVjY__B

Answer 1

shelve in JSON is an object, so a Go map will be created to model it:
case map[string]interface{}:
fmt.Println(k, "is a map:")
for k, v := range vv {
fmt.Println("\t", k, "=", v)
}
With this change output is (try it on the Go Playground):
cabinet is string A
shelve is a map:
color = red
box = 10
See related question:
Accessing Nested Map of Type map[string]interface{} in Golang
Is there any convenient way to get JSON element without type assertion?
Taking a JSON string, unmarshaling it into a map[string]interface{}, editing, and marshaling it into a []byte seems more complicated then it should be