fix: dataset nquads serialization including RDFLib internal default graph identifier (#3262)

* fix: dataset nquads serialization including RDFLib internal default graph identifier * chore: remove json-ld code

Author: edmondchuc

rdflib/plugins/serializers/nquads.py

@@ -3,7 +3,7 @@
 import warnings
 from typing import IO, Any, Optional
 
-from rdflib.graph import ConjunctiveGraph, Graph
+from rdflib.graph import DATASET_DEFAULT_GRAPH_ID, ConjunctiveGraph, Graph
 from rdflib.plugins.serializers.nt import _quoteLiteral
 from rdflib.serializer import Serializer
 from rdflib.term import Literal
@@ -45,17 +45,18 @@ def serialize(
 
 
 def _nq_row(triple, context):
+ graph_name = context.n3() if context and context != DATASET_DEFAULT_GRAPH_ID else ""
  if isinstance(triple[2], Literal):
  return "%s %s %s %s .\n" % (
  triple[0].n3(),
  triple[1].n3(),
  _quoteLiteral(triple[2]),
- context.n3(),
+ graph_name,
  )
  else:
  return "%s %s %s %s .\n" % (
  triple[0].n3(),
  triple[1].n3(),
  triple[2].n3(),
- context.n3(),
+ graph_name,
  )

test/test_serializers/test_nquads_default_graph.py

@@ -0,0 +1,39 @@
+from rdflib import Dataset
+from rdflib.compare import isomorphic
+
+
+def test_nquads_default_graph():
+ data = """
+ @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
+ @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+ @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+
+ {
+ <urn:test> <http://www.w3.org/ns/prov#generatedAtTime> "2012-04-09"^^xsd:date .
+ }
+
+ <urn:test> {
+ <http://greggkellogg.net/foaf#me> a <http://xmlns.com/foaf/0.1/Person> ;
+ <http://xmlns.com/foaf/0.1/knows> "http://manu.sporny.org/about#manu" ;
+ <http://xmlns.com/foaf/0.1/name> "Gregg Kellogg" .
+
+ <http://manu.sporny.org/about#manu> a <http://xmlns.com/foaf/0.1/Person> ;
+ <http://xmlns.com/foaf/0.1/knows> "http://greggkellogg.net/foaf#me" ;
+ <http://xmlns.com/foaf/0.1/name> "Manu Sporny" .
+ }
+ """
+
+ ds = Dataset()
+ ds.parse(data=data, format="trig")
+ output = ds.serialize(format="nquads")
+
+ # The internal RDFLib default graph identifier should not appear in the output.
+ assert "<urn:x-rdflib:default>" not in output
+
+ # Ensure dataset round-trip still works.
+ ds2 = Dataset()
+ ds2.parse(data=output, format="nquads")
+ for graph in ds.graphs():
+ assert isomorphic(graph, ds2.graph(graph.identifier)), print(
+ f"{graph.identifier} not isomorphic"
+ )