ietf-netmod-yang

Yang modeling language - select / deselect one or multiple options within bits type

Is there possibility in YANG language to select one option in bit type leaf, which will deselect all other bits ? What I would like to do is, by default Whole-Platform is selected, but when user selects some other option, the Whole-Platform will be deselected. And otherwise when user selects Whole-Platform, all other options should be deselected.

leaf check-type {
            type bits {
              bit Whole-platform;
              bit NSO-checks;
              bit ESC-checks;
            }
            default "Whole-platform";
 }

bits

Solution

  • No, YANG bits type will not let you do that, since no relation between individual bits ever exists by default - other than the notion of all of them belonging to the same set of "configurable flags".

    This is where a union type would be a viable modeling decision.

    leaf check-type {
  type union {
    type enumeration {
      enum Whole-platform;
    }
    type bits {
      bit NSO-checks;
      bit ESC-checks;
    }
  }
  default Whole-platform;
}

    Doing this implies an XOR (mutual exclusivity) between value Whole-platform and the set of remaining bit values to the reader.

    Valid values:

    <check-type>Whole-platform</check-type>
<check-type>NSO-checks</check-type>
<check-type>NSO-checks ESC-checks</check-type>

    Invalid:

    <check-type>Whole-platform ESC-checks</check-type>

    You could leave your type as is and handle the one bit to rule them all in a description, since that is just human readable normative text.

    description "Implementations must ensure an XOR relationship between
             'Whole-platform' bit value and the other bit values of this
             leaf. When the former is used it means that 
             ...";

    Note: what you are trying to achieve is an implementation detail.