def get_by_group_name(cls, group_name, cache=False, case_insensitive=False):

        if case_insensitive:

            gr = Session.query(cls)\

            .filter(cls.users_group_name.ilike(group_name))

        else:

            gr = Session.query(UsersGroup)\

                .filter(UsersGroup.users_group_name == group_name)

        if cache:

            gr = gr.options(FromCache("sql_cache_short",

                                          "get_user_%s" % group_name))

        return gr.scalar()

    @classmethod

    def get(cls, users_group_id, cache=False):

        users_group = Session.query(cls)

        if cache:

            users_group = users_group.options(FromCache("sql_cache_short",

                                    "get_users_group_%s" % users_group_id))

        return users_group.get(users_group_id)

    @classmethod

    def create(cls, form_data):

        try:

            new_users_group = cls()

            for k, v in form_data.items():

                setattr(new_users_group, k, v)

            Session.add(new_users_group)

            Session.commit()

            return new_users_group

        except:

            log.error(traceback.format_exc())

            Session.rollback()

            raise

    @classmethod

    def update(cls, users_group_id, form_data):

        try:

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

            for k, v in form_data.items():

                if k == 'users_group_members':

                    users_group.members = []

                    Session.flush()

                    members_list = []

                    if v:

                    setattr(users_group, 'members', members_list)

                setattr(users_group, k, v)

            Session.add(users_group)

            Session.commit()

        except:

            log.error(traceback.format_exc())

            Session.rollback()

            raise

    @classmethod

    def delete(cls, users_group_id):

        try:

            # check if this group is not assigned to repo

            assigned_groups = UsersGroupRepoToPerm.query()\

                .filter(UsersGroupRepoToPerm.users_group_id ==

                        users_group_id).all()

            if assigned_groups:

                raise UsersGroupsAssignedException('Group assigned to %s' %

                                                   assigned_groups)

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

            Session.delete(users_group)

            Session.commit()

        except:

            log.error(traceback.format_exc())

            Session.rollback()

            raise

class UsersGroupMember(Base, BaseModel):

    __tablename__ = 'users_groups_members'

    __table_args__ = {'extend_existing':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)

    user = relationship('User', lazy='joined')

    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):