package main

import (
	"fmt"
	"reflect"
)

type Person struct {
	Name      string
	Age       int
	Positions []Position
}

type Position struct {
	Name string
}

func main() {
	data := data()
	data1 := data1()

	val := reflect.ValueOf(data).Elem()
	val1 := reflect.ValueOf(data1)
	for i := 0; i < val.Type().NumField(); i++ {
		if val.Field(i).IsZero() {
			f := val.FieldByName(val.Type().Field(i).Name)
			r := val1.FieldByName(val.Type().Field(i).Name)
			f.Set(r)
		}
	}

	fmt.Println(data)

}

func data() *Person {
	return &Person{}
}

func data1() Person {
	var pos []Position

	pos = append(pos, Position{
		Name: "Mongo",
	})

	pos = append(pos, Position{
		Name: "Golang",
	})
	return Person{
		Name:      "Umidjon",
		Age:       82,
		Positions: pos,
	}
}