mapstructure package example with nested struct and tags

mapstruct.go

package main

import (
	"encoding/json"
	"fmt"

	"github.com/mitchellh/mapstructure"
)

const (
	THAILAND = iota + 1
	USA
	UK
)

type Location struct {
	City    string
	Country int
}

type User struct {
	Name      string                 `mapstructure:"username"`
	Age       int                    `mapstructure:"age"`
	Residence Location               `mapstructure:"location, squash"`
	Emails    []string               `mapstructure:"emails"`
	Social    map[string]interface{} `mapstructure:"social"`
}

func main() {
	var input = map[string]interface{}{
		"username": "artnoi",
		"age":      24,
		"emails":   []string{"[email protected]", "[email protected]"},
		"social": map[string]interface{}{
			"twitter": map[string]interface{}{
				"username": "artnoi",
				"follower": 112,
			},
			"facebook": map[string]interface{}{
				"name":   "Prem Phansuriyanon",
				"joined": "2012",
			},
		},
		"location": map[string]interface{}{
			"City":    "Bangkok",
			"country": THAILAND,
		},
	}

	var output User
	err := mapstructure.Decode(input, &output)
	if err != nil {
		fmt.Println(err)
	}
	fmt.Println(output)

	b, err := json.Marshal(output)
	if err != nil {
		fmt.Println(err)
	}
	fmt.Println(string(b))
}