"Bogaert, Bart (Nokia - BE/Antwerp)" <bart.boga...@nokia.com> writes:
> Changing "count(.) != 1" into "count(../a-list) != 1" in the grouping does > the job as expected. So it seems that count(.) within the context of the > a-list applies to each element in the list and rather than to the list > itself? Both versions of the XPath expression are evaluated once for each entry of the list, and the entry's 'a-list' node is the context node. By definition, '.' selects the context node, so 'count(.)' is always 1. After the change, '..' selects the parent node and 'a-list' then selects all nodes of that name, which are the entries of the list. Note that it would be more efficient to verify the constraint on the parent container, with 'count(a-list) != 1'. Lada > > > > Regards, Bart > > > > From: netmod [mailto:netmod-boun...@ietf.org] On Behalf Of Bogaert, Bart > (Nokia - BE/Antwerp) > Sent: 29 March 2017 12:47 > To: netmod@ietf.org > Subject: [netmod] Question about must statement in grouping > > > > Hi, > > > > We have a question on the usage of a must statement within a grouping. > > > > Assume the following grouping > > > > grouping a-group { > > list a-list { > > must "count(.) != 1" { > > description > > "This list must either be empty or have at least 2 elements"; > > } > > key "entry"; > > leaf entry { > > type uint16; > > } > > leaf another-entry { > > type uint32; > > } > > } > > } > > > > And used in another module > > > > container a-container { > > uses a-group; > > } > > > > The uses actually results in a data-tree like below > > > > +--rw a-container > > +--rw a-list* [entry] > > +--rw entry uint16 > > +--rw another-entry uint32 > > > > Does the usage of the grouping usage also result in the expected behavior > for the must statement when configuring /a-container/a-list? The '.' in the > must statement in the grouping refers to 'a-list' so will that return 2 in > case we have configured 2 elements in /a-container/a-list or should we write > the must statement at the level of 'a-container' stating that "count(a-list) > != 1" (as below)? > > > > grouping a-group { > > list a-list { > > key "entry"; > > leaf entry { > > type uint16; > > } > > } > > } > > > > And used in another module > > > > container a-container { > > uses a-group; > > must "count(a-list) != 1" { > > description > > "This list must either be empty or have at least 2 elements"; > > } > > } > > > > Best regards - Vriendelijke groeten, > > Bart Bogaert > > _______________________________________________ > netmod mailing list > netmod@ietf.org > https://www.ietf.org/mailman/listinfo/netmod -- Ladislav Lhotka, CZ.NIC Labs PGP Key ID: 0xB8F92B08A9F76C67 _______________________________________________ netmod mailing list netmod@ietf.org https://www.ietf.org/mailman/listinfo/netmod
