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]

        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,

            encoding="UTF-8",

            force_defaults=False

        )

    user = relationship('User')

    repository = relationship('Repository')

class UsersGroup(Base, BaseModel):

    __tablename__ = 'users_groups'

    __table_args__ = {'useexisting':True}

    users_group_id = Column("users_group_id", Integer(), nullable=False, unique=True, default=None, primary_key=True)

    users_group_name = Column("users_group_name", String(length=None, convert_unicode=False, assert_unicode=None), nullable=False, unique=True, default=None)

    users_group_active = Column("users_group_active", Boolean(), nullable=True, unique=None, default=None)

class UsersGroupMember(Base, BaseModel):

    __tablename__ = 'users_groups_members'

    __table_args__ = {'useexisting':True}

    users_group_member_id = Column("users_group_member_id", Integer(), nullable=False, unique=True, default=None, primary_key=True)

    users_group_id = Column("users_group_id", Integer(), ForeignKey('users_groups.users_group_id'), nullable=False, unique=None, default=None)

    user_id = Column("user_id", Integer(), ForeignKey('users.user_id'), nullable=False, unique=None, default=None)

    users_group = relationship('UsersGroup')

    def __init__(self, gr_id, u_id):

        self.users_group_id = gr_id

        self.user_id = u_id

class Repository(Base, BaseModel):

    __tablename__ = 'repositories'

    __table_args__ = (UniqueConstraint('repo_name'), {'useexisting':True},)

    repo_id = Column("repo_id", Integer(), nullable=False, unique=True, default=None, primary_key=True)

    repo_name = Column("repo_name", String(length=None, convert_unicode=False, assert_unicode=None), nullable=False, unique=True, default=None)

    repo_type = Column("repo_type", String(length=None, convert_unicode=False, assert_unicode=None), nullable=False, unique=False, default='hg')

    <!-- end box / title -->

    <div class="table">

        <table class="table_disp">

        <tr class="header">

            <th class="left">${_('group name')}</th>

            <th class="left">${_('members')}</th>

            <th class="left">${_('active')}</th>

            <th class="left">${_('action')}</th>

        </tr>

            %for cnt,u_group in enumerate(c.users_groups_list):

                <tr class="parity${cnt%2}">

                    <td>${h.link_to(u_group.users_group_name,h.url('edit_users_group', id=u_group.users_group_id))}</td>

                    <td>${h.bool2icon(u_group.users_group_active)}</td>

                    <td>

                        ${h.form(url('users_group', id=u_group.users_group_id),method='delete')}

                            ${h.submit('remove_','delete',id="remove_group_%s" % u_group.users_group_id,

                            class_="delete_icon action_button",onclick="return confirm('Confirm to delete this users group');")}

                        ${h.end_form()}

                    </td>

                </tr>

            %endfor

        </table>

    </div>

</div>