Re: [netmod] RFC 7951

Hi Kent,

Thanks very much for the response. However, I'm slightly worried you've misunderstood my examples, and as I've been fighting in the #1 corner I want to make sure I give #2 a fair chance.

Given this schema:
module test {
  prefix "test";
  namespace "urn:test";

  container test {
    leaf foo {type string;}
    leaf-list bar {type string;}
    leaf baz {type string;}
  }
}

Is this valid (#1):
{
        "test:test": {
                "foo": "test1",
                "bar": [],
                "baz": "test2"
        }
}

and is this valid (#2):
{
        "test:test": {
                "foo": "test1",
                "baz": "test2"
        }
}

To make sure I didn't miss something I verified this with yanglint 0.16.105 (what ubuntu gave me), and that accepts #2 but not #1 (it rejects #1 with err : Invalid JSON data (unexpected value). (/test:test/bar)).
To be really clear this is accepted:
{
        "test:test": {
                "foo": "test1",
                "bar": ["test3"],
                "baz": "test2"
        }
}

Thanks,
Jack

________________________________
From: Kent Watsen <kent+ietf@watsen.net>
Sent: 29 March 2022 18:14
To: Jack Rickard <jack.rickard@microsoft.com>
Cc: draft-ietf-netmod-yang-json@ietf.org <draft-ietf-netmod-yang-json@ietf.org>; netmod@ietf.org <netmod@ietf.org>
Subject: Re: [netmod] RFC 7951 - JSON encoding of empty lists

#1 is an empty list (or leaf-list).  This is what you want.

#2 is a list containing one element, which is an empty container (or, in Python term's, an empty 'dict').

Yanglint 1.x used to accept #1, kinks are being worked out on the 2.x branch.

Kent // contributor

On Mar 29, 2022, at 10:21 AM, Jack Rickard <jack.rickard=40microsoft.com@dmarc.ietf.org<mailto:jack.rickard=40microsoft.com@dmarc.ietf.org>> wrote:

Hi,

I think I’ve found an ambiguity in RFC 7951, and I’d like your input on what was intended and what the best behaviour to exhibit is.

Section 5.3 and 5.4 of RFC 7951 - JSON Encoding of Data Modeled with YANG (ietf.org)<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc7951%23section-5.3&data=04%7C01%7Cjack.rickard%40microsoft.com%7Ca33f2d22f70f4de7a87808da11a79ae4%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637841709447361395%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=2jqJW1VVJyft9CVC3T5xCgXvlt4Zsd7c7mdtBrKSpdM%3D&reserved=0> describe the encoding of leaf-lists and lists, however it’s unclear how an empty list should be encoded. Should it be encoded as:

  1.  An empty array: {“list”: []}
  2.  A missing field: {}

I’ve seen libraries go either way, libyang only accepts 2 but the python yangson library accepts both (I’m not sure which is the default).

Thanks,
Jack Rickard
he/him
Software Engineer
jack.rickard@microsoft.com<mailto:jack.rickard@microsoft.com>

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