type User struct {
    Username string
    Password string
    Email    string
}

func (c App) Register(user User) revel.Result {
    c.Validation.Required(user.Username).Message("Missing username")
    c.Validation.Required(user.Password).Message("Missing password")
    c.Validation.Required(user.Email).Message("Missing email")
    if c.Validation.HasErrors() {
        c.Validation.Keep()
        c.FlashParams()
    }
    return c.Redirect(App.Index)
}