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

Andy Bierman <andy@yumaworks.com> Mon, 24 June 2019 17:11 UTC

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From: Andy Bierman <andy@yumaworks.com>
Date: Mon, 24 Jun 2019 10:11:39 -0700
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To: =?UTF-8?Q?Michal_Va=C5=A1ko?= <mvasko@cesnet.cz>
Cc: "Rob Wilton (rwilton)" <rwilton@cisco.com>, netmod <netmod@ietf.org>
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Subject: Re: [netmod] ?==?utf-8?q? mandatory choice with non-presence container case
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On Mon, Jun 24, 2019 at 10:01 AM Michal Vaško <mvasko@cesnet.cz> wrote:

> Hi Rob,
> I think there is a problem in the RFC because using only allowed steps I
> got invalid data from initially valid data. That cannot be correct.
>
>
No.  See sec. 7.5.7

   If a non-presence container does not have any child nodes, the
   container may or may not be present in the XML encoding.


Just because your retrieval does not contain the NP-container, that does
not mean the
NP-container was not present in the server for the mandatory-stmt
validation.

Regards,
> Michal
>
>
Andy


> On Monday, June 24, 2019 18:52 CEST, "Rob Wilton (rwilton)" <
> rwilton@cisco.com> wrote:
>
> > Hi Michal,
> >
> > My thoughts:
> >
> > According to 7.5.1:
> >
> >    In the first style, the container has no meaning of its own, existing
> >    only to contain child nodes.  In particular, the presence of the
> >    container node with no child nodes is semantically equivalent to the
> >    absence of the container node.  YANG calls this style a "non-presence
> >    container".  This is the default style.
> >
> > Hence your request (because the NP container does not have any children)
> is equivalent to:
> >
> >  <TOP>
> >    <L/>
> >  </TOP>
> >
> > which fails the "mandatory" check.
> >
> > Thanks,
> > Rob
> >
> >
> > > -----Original Message-----
> > > From: netmod <netmod-bounces@ietf.org> On Behalf Of Michal Vaško
> > > Sent: 24 June 2019 17:39
> > > To: netmod <netmod@ietf.org>
> > > Subject: [netmod] mandatory choice with non-presence container case
> > >
> > > Hi,
> > > I have encountered a situation that I think is not covered by RFC
> 7950. My
> > > specific use-case was as follows.
> > >
> > > model:
> > >
> > > container TOP {
> > >   leaf L {
> > >     type empty;
> > >   }
> > >   choice A {
> > >     mandatory true;
> > >     container C;
> > >   }
> > > }
> > >
> > > data:
> > >
> > > <TOP>
> > >   <L/>
> > >   <C/>
> > > </TOP>
> > >
> > > Parsing was successful, but printing these data back to XML produced:
> > >
> > > <TOP>
> > >   <L/>
> > > </TOP>
> > >
> > > and parsing this correctly failed with missing mandatory choice.
> According
> > > to section 7.5.7 [1], I think the C container could be omitted but the
> > > whole situation does not seem correct. Thank you for any input.
> > >
> > > Regards,
> > > Michal
> > >
> > > [1] https://tools.ietf.org/html/rfc7950#section-7.5.7
> > >
> > > _______________________________________________
> > > netmod mailing list
> > > netmod@ietf.org
> > > https://www.ietf.org/mailman/listinfo/netmod
>
>
>
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