except formencode.Invalid, errors:

            return htmlfill.render(

                render('admin/users_groups/users_group_edit.html'),

                defaults=errors.value,

                errors=errors.error_dict or {},

                prefix_error=False,

                encoding="UTF-8")

        except Exception:

            log.error(traceback.format_exc())

            h.flash(_('error occurred during update of users group %s') \

                    % request.POST.get('users_group_name'), category='error')

        return redirect(url('users_groups'))

    def delete(self, id):

        """DELETE /users_groups/id: Delete an existing item"""

        # Forms posted to this method should contain a hidden field:

        #    <input type="hidden" name="_method" value="DELETE" />

        # Or using helpers:

        #    h.form(url('users_group', id=ID),

        #           method='delete')

        # url('users_group', id=ID)

    def show(self, id, format='html'):

        """GET /users_groups/id: Show a specific item"""

        # url('users_group', id=ID)

    def edit(self, id, format='html'):

        """GET /users_groups/id/edit: Form to edit an existing item"""

        # url('edit_users_group', id=ID)

        c.users_group = self.sa.query(UsersGroup).get(id)

        if not c.users_group:

            return redirect(url('users_groups'))

        c.users_group.permissions = {}

        c.group_members = [(x.user_id, x.user.username) for x in

                           c.users_group.members]

        print c.group_members, 'x' * 100

        c.available_members = [(x.user_id, x.username) for x in

                               self.sa.query(User).all()]

        defaults = c.users_group.get_dict()

        return htmlfill.render(

            render('admin/users_groups/users_group_edit.html'),

            defaults=defaults,

    def update(self, users_group_id, form_data):

        try:

            users_group = self.get(users_group_id, cache=False)

            for k, v in form_data.items():

                if k == 'users_group_members':

                    users_group.members = []

                    self.sa.flush()

                    members_list = []

                    if v:

                        for u_id in set(v):

                            members_list.append(UsersGroupMember(users_group_id,

                                                             u_id))

                    setattr(users_group, 'members', members_list)

                setattr(users_group, k, v)

            self.sa.add(users_group)

            self.sa.commit()

        except:

            log.error(traceback.format_exc())

            self.sa.rollback()

            raise