package main

import (
	"database/sql/driver"
	"encoding/json"
	"fmt"

	"github.com/jinzhu/copier"
)

type IntArray []int

func (a IntArray) Value() (driver.Value, error) {
	return json.Marshal(a)
}

type Int int

type From struct {
	Data IntArray
}

type To struct {
	Data []Int
}

func main() {
	var (
		from = From{
			Data: IntArray{1, 2, 3},
		}
		to To
	)
	if err := copier.Copy(&to, from); err != nil {
		panic(err)
	}

	fmt.Printf("%#v", to)
}

main.To{Data:[]main.Int(nil)}

main.To{Data:[]main.Int{1, 2, 3}}