Re: [netmod] ?= ?==?utf-8?q? mandatory choice with non-presence container cas

On Tue, 2019-06-25 at 09:58 +0200, Martin Bjorklund wrote:
> Ladislav Lhotka <lhotka@nic.cz> wrote:
> > Kent Watsen <kent@watsen.net> writes:
> > 
> > > Hi Michal,  
> > > > I agree, but these valid data were correctly printed into invalid
> > > > data. I do not think printing is allowed to change the validity of
> > > > data.
> > >  The NP-container text is unclear.
> > 
> > This issue IMO has more to do with the "mandatory" statement under
> > "choice". Similar problems can be caused by data nodes that depend on
> > "when". For example:
> > 
> > choice sel {
> >    madatory true;
> >    leaf foo {
> >        when "...";
> >        ...
> >    }
> >    leaf bar { ... }
> >    leaf baz { ... }
> > 
> > If "foo" exists in instance data but its when condition becomes false,
> > the server is expected to remove the "foo" instance, but what next?
> > The data becomes invalid, but the server can hardly include "bar" or
> > "baz" on its own.
> 
> Right, so that change (that would make the when condition false) will
> be rejected by the server, since the resulting config would be
> invalid.

Yes, this is actually the only sane behaviour that should be applied each time a
when constraint becomes invalid - rather then auto-delete the conditional nodes.

Regarding NP-containers, I think their character implies that they can never be
empty in the schema. This should probably be stated in the YANG spec.

Lada

> 
> 
> /martin
> 
> 
> 
> 
> > Lada
> > 
> > > I'm unsure if you saw the thread in NETCONF, but I filed this issue
> > > over the weekend.  Please add to it, if only to include a link to this
> > > thread: https://github.com/netmod-wg/yang-next/issues/88. Thanks, Kent
> > > _______________________________________________ netmod mailing list
> > > netmod@ietf.org https://www.ietf.org/mailman/listinfo/netmod
> > 
> > -- 
> > Ladislav Lhotka Head, CZ.NIC Labs PGP Key ID: 0xB8F92B08A9F76C67
> > 
> > _______________________________________________
> > netmod mailing list
> > netmod@ietf.org
> > https://www.ietf.org/mailman/listinfo/netmod
> > 
-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67