Creates a struct from dotenv file. Has ability to json parse as well in case field is struct and has a key string against it in the env map. Constructs key for a namespace - eg start with "DEV" or "PROD". Input is original type we want to construct, env to store map of key and value (as string) and current active key.

struct-of-env.go

package main

import (
	"encoding/json"
	"fmt"
	"reflect"
	"strconv"
	"strings"
)

func LoadConfig(_type reflect.Type, env map[string]string, key string) reflect.Value {
	switch _type.Kind() {
	case reflect.String:
		if envValue, ok := env[key]; ok {
			logrus.Info("envValue=", envValue, env)
			return reflect.ValueOf(&envValue).Elem()
		}
		panic(fmt.Errorf("Key %s not found %+v", key, env))
	case reflect.Int:
		fallthrough
	case reflect.Int8:
		fallthrough
	case reflect.Int16:
		fallthrough
	case reflect.Int32:
		fallthrough
	case reflect.Int64:
		v, err := strconv.Atoi(env[key])
		if err != nil {
			panic(err)
		}
		return reflect.ValueOf(&v).Elem()
	case reflect.Float32:
		fallthrough
	case reflect.Float64:
		v, err := strconv.ParseFloat(env[key], 10)
		if err != nil {
			panic(err)
		}
		return reflect.ValueOf(&v).Elem()
	case reflect.Struct:
		value := reflect.New(_type).Elem()
		if envValue, ok := env[key]; ok {
			obj := value.Interface()
			err := json.Unmarshal([]byte(envValue), &obj)
			if err == nil {
				return value
			}
		}
		for i := 0; i < value.NumField(); i++ {
			field := value.Field(i)
			fieldName := value.Type().Field(i).Name
			fieldKey := fmt.Sprintf("%s_%s", key, strings.ToUpper(fieldName))
			collected := LoadConfig(field.Type(), env, fieldKey)
			field.Set(collected)
		}
		return value
	}
	return reflect.ValueOf(nil)
}