def create_custom_dag_permission_view(self, session=None):
        """
        
        """
        self.log.debug('Fetching a set of all permission, view_menu from FAB meta-table')

        def merge_pv(perm, view_menu):
            """Create permission view menu only if it doesn't exist"""
            if view_menu and perm and (view_menu, perm) not in all_pvs:
                self._merge_perm(perm, view_menu)

        all_pvs = set()
        for pv in self.get_session.query(self.permissionview_model).all():
            if pv.permission and pv.view_menu:
                all_pvs.add((pv.permission.name, pv.view_menu.name))

        # Get all the active / paused dags and insert them into a set
        all_dags_models = session.query(models.DagModel)\
            .filter(or_(models.DagModel.is_active, models.DagModel.is_paused))\
            .filter(~models.DagModel.is_subdag).all()

        # create can_dag_edit and can_dag_read permissions for every dag(vm)
        for dag in all_dags_models:
            for perm in self.DAG_PERMS:
                merge_pv(perm, dag.dag_id)

        # for all the dag-level role, add the permission of viewer
        # with the dag view to ab_permission_view
        all_roles = self.get_all_roles()
        user_role = self.find_role('User')

        dag_role = [role for role in all_roles if role.name not in EXISTING_ROLES]
        update_perm_views = []

        # need to remove all_dag vm from all the existing view-menus
        dag_vm = self.find_view_menu('all_dags')
        ab_perm_view_role = sqla_models.assoc_permissionview_role
        perm_view = self.permissionview_model
        view_menu = self.viewmenu_model

        all_perm_view_by_user = session.query(ab_perm_view_role)\
            .join(perm_view, perm_view.id == ab_perm_view_role
                  .columns.permission_view_id)\
            .filter(ab_perm_view_role.columns.role_id == user_role.id)\
            .join(view_menu)\
            .filter(perm_view.view_menu_id != dag_vm.id)
        all_perm_views = set([role.permission_view_id for role in all_perm_view_by_user])

        for role in dag_role:
            # Get all the perm-view of the role
            existing_perm_view_by_user = self.get_session.query(ab_perm_view_role)\
                .filter(ab_perm_view_role.columns.role_id == role.id)

            existing_perms_views = set([pv.permission_view_id
                                        for pv in existing_perm_view_by_user])
            missing_perm_views = all_perm_views - existing_perms_views

            for perm_view_id in missing_perm_views:
                update_perm_views.append({'permission_view_id': perm_view_id,
                                          'role_id': role.id})

        if update_perm_views:
            self.get_session.execute(ab_perm_view_role.insert(), update_perm_views)
        self.get_session.commit()