Re: [yang-doctors] when statement of an optional leaf? Does it make an optional leaf?

[Ladislav Lhotka <[e-mail]>]

Hi Benoit,

"maintenance-contact" may remain mandatory - due to its default value, "under-maintenace" is always present, as far as XPath evaluation is concerned.

But because of this, your when expression probably doesn't have the effect that you expect: it will always be true. I think it needs to be changed to

    when "../under-maintenance = 'true'";

Lada

Benoit Claise <bclaise=[e-mail]> writes:

> YANG doctors,
>
> $ pyang -f tree  ietf-service-assurance.yang
> module: ietf-service-assurance
>    +--ro assurance-graph-version?       yang:counter32
>    +--ro assurance-graph-last-change?   yang:date-and-time
>    +--rw subservices
>       +--rw subservice* [type id]
>          +--rw type                                identityref
>          +--rw id                                  string
>          +--ro last-change?                        yang:date-and-time
>          +--ro label?                              string
>          +--rw under-maintenance?                  boolean
>          +--rw maintenance-contact string <===============================
>          +--rw (parameter)?
>          |  +--:(service-instance-parameter)
>          |     +--rw service-instance-parameter
>          |        +--rw service?         string
>          |        +--rw instance-name?   string
>          +--ro health-score?                       uint8
>          +--rw symptoms
>          |  +--ro symptom* [start-date-time id]
>          |     +--ro id                     string
>          |     +--ro health-score-weight?   uint8
>          |     +--ro label?                 string
>          |     +--ro start-date-time        yang:date-and-time
>          |     +--ro stop-date-time?        yang:date-and-time
>          +--rw dependencies
>             +--rw dependency* [type id]
>                +--rw type               -> /subservices/subservice/type
>                +--rw id                 -> 
> /subservices/subservice[type=current()/../type]/id
>                +--rw dependency-type?   identityref
>
> The YANG modules comes from 
> https://datatracker.ietf.org/doc/draft-claise-opsawg-service-assurance-yang/
> Have a look at 
> https://raw.githubusercontent.com/YangModels/yang/ecb622b214e59c5f6312e915d4d65823a6485852/experimental/ietf-extracted-YANG-modules/[e-mail]
>
> The leafs in question:
>
>            leaf under-maintenance {
>              type boolean;
>              default false;
>              description
>                "An optional flag indicating whether this particular subservice is under
>                maintenance. Under this circumstance, the subservice symptoms and the
>                symptoms of its dependencies in the assurance graph should not be taken
>                into account. Instead, the subservice should send a 'Under Maintenance'
>                single symptom.
>
>                The operator changing the under-maintenance value must set the
>                maintenance-contact variable.
>
>                When the subservice is not under maintenance any longer, the
>                under-maintenance flag must return to its default value and
>                the under-maintenance-owner variable deleted.";
>            }
>            leaf maintenance-contact {
>     when "../under-maintenance";
>              type string;
>              mandatory true;
>              description
>                "A string used to model an administratively assigned name of the
>                resource that changed the under-maintenance value to 'true.
>
>                It is suggested that this name contain one or more of the following:
>                IP address, management station name, network manager's name, location,
>                or phone number. In some cases the agent itself will be the owner of
>                an entry. In these cases, this string shall be set to a string
>                starting with 'monitor'.";
>            }
>
> In case of a leaf (maintenance-contact) with a when statement pointing 
> to an optional leaf (under-maintenance), should the leaf 
> (maintenance-contact) be marked as optional in the tree output?
>
> Regards, Benoit
> _______________________________________________
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-- 
Ladislav Lhotka 
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67