package main

import (
	"fmt"
	"reflect"
)

type User struct {
	ID  string
	Foo string
	Bar int
	pri string
	Pub int
}

func main() {
	user := User{"id1", "foo", 2, "skip me without panic", 4}
	fmt.Println(user.String())
	//ID: id1
	//Foo: foo
	//Bar: 2
	//Pub: 4
}

func (u User) String() string {
	str := ""
	fa := reflect.ValueOf(u)
	for i := 0; i < fa.NumField(); i++ {
		if !fa.Field(i).CanInterface() { // skip private for avoid panic
			continue
		}
		str += fmt.Sprintf("%v: %v\n", fa.Type().Field(i).Name, fa.Field(i).Interface())
	}
	return str
}
Play
REF
