evnuh

func Save(i interface{}, id int) {
    data, err := json.Marshal(i)
    check(err)
    if id == 0 {
        _, err = app.DB.Exec(`INSERT INTO users(data) VALUES ($1) `, string(data))
    } else {
        _, err = app.DB.Exec(`UPDATE users SET data = $1 WHERE id=$2`, string(data), id)
    }
    check(err)
}

u := User{}
a := Admin{}

Save(u, u.ID)
Save(a, a.ID)

interface Model {
    getID()
    setID()
}

func Save(i model) {
	data, err := json.Marshal(i)
	var id int
	check(err)
	if i.getID() == 0 {
		err = app.DB.QueryRow(`INSERT INTO users(data) VALUES ($1) RETURNING id`, string(data)).Scan(&id)
		i.setID(id)
	} else {
		_, err = app.DB.Exec(`UPDATE users SET data = $1 WHERE id=$2`, string(data), i.getID())
	}
	check(err)
}