private async void btnSave_Click(object sender, EventArgs e)
        {
            if (this.ValidateChildren())
            {
                var roles = clbRoles.CheckedItems.Cast <Model.Role>().Select(x => x.RoleId).ToList();

                request.FirstName            = txtFirstName.Text;
                request.LastName             = txtLastName.Text;
                request.Email                = txtEmail.Text;
                request.PhoneNumber          = txtTelephone.Text;
                request.Password             = txtPassword.Text;
                request.PasswordConfirmation = txtPasswordConfirmation.Text;
                request.Roles                = roles;

                if (_id.HasValue)
                {
                    await _userService.Update <Model.User>(_id, request);
                }
                else
                {
                    await _userService.Insert <Model.User>(request);
                }
                MessageBox.Show("Uspjesno!");
                this.Close();
                var frm            = new ucUsers();
                var frmIndex       = Application.OpenForms["frmIndex"];
                var panelContainer = frmIndex.Controls.Find("panelMain", true).FirstOrDefault() as Panel;

                PanelHelper.AddPanel(panelContainer, frm);
            }
        }
        private async void btnDelete_Click(object sender, EventArgs e)
        {
            var user = await _userService.Delete <Model.User>(_id);

            MessageBox.Show("Uspjesno obrisano!");
            this.Close();
            var frm            = new ucUsers();
            var frmIndex       = Application.OpenForms["frmIndex"];
            var panelContainer = frmIndex.Controls.Find("panelMain", true).FirstOrDefault() as Panel;

            PanelHelper.AddPanel(panelContainer, frm);
        }