def _get_one(ref_or_id, requester_user):
        """
        List merged action & runner parameters by action id or ref.

        Handle:
            GET /actions/views/parameters/1
        """
        if ResourceReference.is_resource_reference(ref_or_id):
            action_db = LookupUtils._get_action_by_ref(ref_or_id)
        else:
            action_db = LookupUtils._get_action_by_id(ref_or_id)

        permission_type = PermissionType.ACTION_VIEW
        rbac_utils = get_rbac_backend().get_utils_class()
        rbac_utils.assert_user_has_resource_db_permission(
            user_db=requester_user,
            resource_db=action_db,
            permission_type=permission_type,
        )

        runner_db = LookupUtils._get_runner_by_name(action_db.runner_type["name"])
        all_params = action_param_utils.get_params_view(
            action_db=action_db, runner_db=runner_db, merged_only=True
        )

        return {"parameters": all_params}

        List merged action & runner parameters by action id or ref.

        Handle:
            GET /actions/views/parameters/1
        
st2api/st2api/controllers/v1/action_views.py