"Sterne, Jason (Nokia - CA/Ottawa)" <jason.ste...@nokia.com> wrote:
> Thx. In the case I'm most concerned about, a-list (and all
> descendants) is config true and 'entry' is the key leaf.
No need to check for a key's existance!
> So all
> a-list entries have a node called 'entry' by definition.
>
> (I'm regretting using the name 'entry' for my key now in this example 😊
>
> In this case it seems all the following result in the equivalent behavior
> (checking that a-list has at least one entry):
> must "../a-list";
> must "../a-list[entry=*]";
> must "../a-list[entry]"; <- this confuses me but I'll take your word
> for it
> must "../a-list/entry";
> must "../a-list[entry=*]/entry";
> must "../a-list[entry]/entry"; <- not sure about this one
Yes. As would:
must "../a-list[1=1]/entry";
must "../a-list[count(*) > 0]/entry";
etc; if you want to have a confusing expression instead of the simple:
must "../a-list";
/martin
>
> Rgds,
> Jason
>
> > -----Original Message-----
> > From: Martin Bjorklund [mailto:m...@tail-f.com]
> > Sent: Wednesday, March 28, 2018 1:28 PM
> > To: Sterne, Jason (Nokia - CA/Ottawa) <jason.ste...@nokia.com>
> > Cc: alex.campb...@aviatnet.com; netmod@ietf.org
> > Subject: Re: [netmod] YANG 'must' Xpaths, predicates and wildcards
> >
> > "Sterne, Jason (Nokia - CA/Ottawa)" <jason.ste...@nokia.com> wrote:
> > > Thanks Alex. Sorry about those sloppy mistakes. I agree about the
> > > ../a-list and I should have said count > 0.
> > >
> > > In the 2nd part of my email, my intention was to only allow foo to be
> > > configured if a-list has at least one entry configured. So I don't
> > > think min-elements 1 would work. I don't want to always require an
> > > entry in a-list. I only want to require one if foo is configured.
> > >
> > > I guess this also achieves the same thing right ?
> > > must "../a-list[entry=*]";
> >
> > Yes, if all a-list entries has a node called "entry". But if that't
> > what you want, do:
> >
> > must "../a-list[entry]";
> >
> >
> > > If foo has a default value, then does that mean the "must" is
> > > evaluated even if foo is deleted from the config ?
> > > leaf foo {
> > > must "../a-list"; <- always evaluated because of default ?
> > > type uint16;
> > > default 5;
> > > }
> > > If the must is always evaluated then it would be the equivalent of
> > > having min-elements 1 in a-list.
> >
> >
> > Correct.
> >
> >
> > /martin
> >
> > >
> > > Rgds,
> > > Jason
> > >
> > > From: Alex Campbell [mailto:alex.campb...@aviatnet.com]
> > > Sent: Tuesday, March 27, 2018 9:57 PM
> > > To: Sterne, Jason (Nokia - CA/Ottawa) <jason.ste...@nokia.com>;
> > > net...@ietf..org
> > > Subject: Re: YANG 'must' Xpaths, predicates and wildcards
> > >
> > >
> > > Hi,
> > >
> > >
> > >
> > > For one thing, it should be ../a-list since a-list is not a child of
> > > foo.
> > >
> > > Also - if foo is not configured and has no default value, then any
> > > must expressions in foo are not evaluated because it is not part of
> > > the "accessible tree". (I tested this in ConfD)
> > >
> > > Apart from these issues, yes it will behave as you expect - it will
> > > fail if a-list contains no entries.
> > >
> > >
> > >
> > > must "count(a-list) > 1"; is not equivalent since it requires at least
> > > two entries.
> > >
> > >
> > >
> > > However, you can more simply add a min-elements 1; statement to a-list
> > > to achieve the same goal - no XPath required.
> > >
> > >
> > >
> > > ________________________________
> > > From: netmod <netmod-boun...@ietf.org<mailto:netmod-
> > boun...@ietf.org>>
> > > on behalf of Sterne, Jason (Nokia - CA/Ottawa)
> > > <jason.ste...@nokia.com<mailto:jason.ste...@nokia.com>>
> > > Sent: Wednesday, 28 March 2018 1:10 p.m.
> > > To: netmod@ietf.org<mailto:netmod@ietf.org>
> > > Subject: [netmod] YANG 'must' Xpaths, predicates and wildcards
> > >
> > > Hi all,
> > >
> > > I'm pretty sure that this xpath (e.g. in a must statement) isn't
> > > correct:
> > >
> > > (A) ../container-a/list-b[name=*]/some-leaf
> > >
> > > and should just be this instead:
> > >
> > > (B) ../container-a/list-b/some-leaf
> > >
> > > Or is the * an allowable wildcard for a key value in a predicate ?
> > >
> > > I also had a question about whether the following "must" correctly
> > > checks that at least one entry exists in a-list.
> > >
> > > container c1 {
> > > leaf foo {
> > > must "a-list";
> > > type uint16;
> > > }
> > > list a-list {
> > > key "entry";
> > > leaf entry {
> > > type uint16;
> > > }
> > > leaf another-entry {
> > > type uint32;
> > > }
> > > }
> > > }
> > >
> > > I think I could also replace that must with the following:
> > > must "count(a-list) > 1";
> > > but does must "a-list"; achieve the same thing ?
> > >
> > > Rgds,
> > > Jason
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