mapstructure custom data type

sample.go

package main

import (
	"fmt"
	"log"
	"reflect"

	"github.com/mitchellh/mapstructure"
)

type Data struct {
	Countries []string
	City      string
	Active    bool
}

func StrToBool(f reflect.Type, t reflect.Type, data interface{}) (interface{}, error) {
	if t.Kind() != reflect.Bool {
		return data, nil
	}

	// Convert it by parsing
	if data.(string) == "true" {
		return true, nil
	} else if data.(string) == "false" {
		return false, nil
	}

	return nil, fmt.Errorf("failed parsing bool %v", data)
}

func main() {

	map_data := map[string]string{
		"countries": "IR,US",
		"city": "test",
		"active": "true",
	}
	var data Data

	cfg := &mapstructure.DecoderConfig{
		DecodeHook: mapstructure.ComposeDecodeHookFunc(StrToBool, mapstructure.StringToSliceHookFunc(",")),
		Result: &data,
	}
	ms, _ := mapstructure.NewDecoder(cfg)
	if err := ms.Decode(map_data); err != nil {
		log.Fatalf("Failed! %s", err)
	}

	fmt.Printf("%#v\n", data)
}