json-ld serialize doesnt failt or raise warning, when producing invalid syntax; type is literal

[WhiteGobo]

So im not sure if this is a bug. So i tested if there are any problems bumping up the default version of json-ld to 1.1 and the roundtrip test failed. Background is #2606

[
  {
    "@id": "file:///somewhere/",
    "@type": [
      {
        "@value": "thing too"
      }
    ]
  },
  {
    "@id": "file:///somewhere/#",
    "@type": [
      {
        "@value": "another thing"
      }
    ]
  }
]

Cant pe parsed with version 1.1 but it works with 1.0.

Graph().parse(jsonfile, format="json-ld", version=1.1)

It seems that it tries to get an existing reference to the type {"@value": "another thing"} which is a dict and cant be hashed. It doesnt try to do this in version 1.0.

[WhiteGobo]

It fails at this point: (rt is the dict {"@value": "another thing"})

rdflib/rdflib/plugins/shared/jsonld/context.py

Line 162 in 9834665

typeterm = self.terms.get(rt)

This is the testfile that fails to be loaded again:

rdflib/test/data/suites/n3roundtrip/rdf-test-11.n3

Lines 1 to 14 in 9834665

	# Test the syntactic items for abbreviation.
	# This is *not* testing rule application.
	@prefix : <#> .
	_:a => _:b .
	_:a <= _:b .
	_:a = _:b .
	# 'this' refers to the current formula so is not legal for RDF
	# this a "thing".
	<> a "thing too".
	<#> a "another thing".

[WhiteGobo]

Ok i'm pretty sure this is a bug in the serializer and not in the parser. @type should be a term, a compact iri or a reference and shouldnt contain value objects.(edited after comment from edmondchuc)

I would change the parser to give more leniency and let it fallback to its behaviour of version 1.0, till the bug in the serializer is repaired. We could remove this behaviour or at least raise a warning in the next major release of rdflib.

[WhiteGobo]

@prefix foaf: <http://xmlns.com/foaf/0.1/> .
[] a foaf:Person.

is serialized to

[
  {
    "@id": "_:ncd6c76112bd148c0a0c9a8a035854d6cb1",
    "@type": [
      "http://xmlns.com/foaf/0.1/Person"
    ]
  }
]

As far as i understand it should be "@type": "http://xmlns.com/foaf/0.1/Person" instead, without the [...]

[edmondchuc]

As far as i understand it should be "@type": "http://xmlns.com/foaf/0.1/Person" instead, without the [...]

I guess the serialized result you got there is just the JSON-LD in the expanded form. If you don't want it as a list, you can use compaction. Behaviour of @type here is relevant? https://www.w3.org/TR/json-ld11/#using-set-with-type.

Sorry, haven't looked too much into how this is related to your original issue though.

[WhiteGobo]

Mh your right. I still think value objects arent allowed in that array. so things like {"@type": [{"@value": "thing too"}]} shouldnt be allowed. (ive changed my comment above to reflect this)

[edmondchuc]

Yeah, probably the JSON-LD processor in RDFLib is just not as strict. Your provided example fails in https://json-ld.org/playground/ when the value of @type is a value object.

JSON-LD example: https://tinyurl.com/2atu5gdy

[WhiteGobo]

Ive renamed the issue, because of the bug in the serializer. Now Roundtrip test with default jsonld version 1.1 will succeed.