Fix issue 1808

rdflib/graph.py

@@ -23,7 +23,6 @@
 from urllib.request import url2pathname
 from warnings import warn
 
-import rdflib.term
 import rdflib.util  # avoid circular dependency
 from rdflib import exceptions, namespace, plugin, query
 from rdflib.collection import Collection
@@ -34,7 +33,7 @@
 from rdflib.resource import Resource
 from rdflib.serializer import Serializer
 from rdflib.store import Store
-from rdflib.term import BNode, Genid, IdentifiedNode, Literal, Node, URIRef
+from rdflib.term import BNode, Genid, IdentifiedNode, Literal, Node, RDFLibGenid, URIRef
 
 assert Literal  # avoid warning
 assert Namespace  # avoid warning
@@ -1510,10 +1509,17 @@ def do_de_skolemize(uriref, t):
 
         def do_de_skolemize2(t):
             (s, p, o) = t
-            if isinstance(s, Genid):
-                s = s.de_skolemize()
-            if isinstance(o, Genid):
-                o = o.de_skolemize()
+
+            if RDFLibGenid._is_rdflib_skolem(s):
+                s = RDFLibGenid(s).de_skolemize()
+            elif Genid._is_external_skolem(s):
+                s = Genid(s).de_skolemize()
+
+            if RDFLibGenid._is_rdflib_skolem(o):
+                o = RDFLibGenid(o).de_skolemize()
+            elif Genid._is_external_skolem(o):
+                o = Genid(o).de_skolemize()
+
             return s, p, o
 
         retval = Graph() if new_graph is None else new_graph

rdflib/term.py

@@ -465,7 +465,7 @@ def skolemize(
         if basepath is None:
             basepath = rdflib_skolem_genid
         skolem = "%s%s" % (basepath, str(self))
-        return RDFLibGenid(urljoin(authority, skolem))
+        return URIRef(urljoin(authority, skolem))
 
 
 class Literal(Identifier):

test/test_graph/test_skolemization.py

@@ -0,0 +1,93 @@
+import logging
+import re
+from test.testutils import GraphHelper
+from typing import Pattern, Union
+
+import pytest
+
+from rdflib import Graph
+from rdflib.namespace import Namespace
+from rdflib.term import BNode, Literal, URIRef
+
+EG = Namespace("http://example.com/")
+
+base_triples = {
+    (EG.subject, EG.predicate, EG.object0),
+    (EG.subject, EG.predicate, EG.object1),
+}
+
+
+@pytest.mark.parametrize(
+    ["node", "expected_uri"],
+    [
+        (URIRef("http://example.com"), None),
+        (Literal("some string in here ..."), None),
+        (BNode("GMeng4V7"), "http://rdlib.net/.well-known/genid/rdflib/GMeng4V7"),
+        (
+            BNode(),
+            re.compile("^" + re.escape("http://rdlib.net/.well-known/genid/rdflib/")),
+        ),
+    ],
+)
+def test_skolemization(
+    node: Union[BNode, URIRef, Literal], expected_uri: Union[Pattern[str], str, None]
+) -> None:
+    g = Graph()
+    for triple in base_triples:
+        g.add(triple)
+    g.add((EG.scheck, EG.pcheck, node))
+    assert len(g) == 3
+    dsg = g.skolemize()
+    if expected_uri is None:
+        GraphHelper.assert_sets_equals(g, dsg)
+    else:
+        assert len(dsg) == len(g)
+        iset = GraphHelper.triple_or_quad_set(dsg)
+        logging.debug("iset = %s", iset)
+        assert iset.issuperset(base_triples)
+        check_triples = list(dsg.triples((EG.scheck, EG.pcheck, None)))
+        assert len(check_triples) == 1
+        sbnode = check_triples[0][2]
+        logging.debug("sbnode = %s, sbnode_value = %s", sbnode, f"{sbnode}")
+        assert isinstance(sbnode, URIRef)
+        if isinstance(expected_uri, str):
+            assert expected_uri == f"{sbnode}"
+        else:
+            assert expected_uri.match(f"{sbnode}") is not None
+
+
+@pytest.mark.parametrize(
+    ["iri", "expected_bnode_value"],
+    [
+        ("http://example.com", None),
+        ("http://example.com/not/.well-known/genid/1", None),
+        ("http://rdlib.net/not/.well-known/genid/1", None),
+        ("http://example.com/.well-known/genid/1", re.compile("^N")),
+        ("http://rdlib.net/.well-known/genid/rdflib/GMeng4V7", "GMeng4V7"),
+    ],
+)
+def test_deskolemization(
+    iri: str, expected_bnode_value: Union[str, None, Pattern[str]]
+) -> None:
+    g = Graph()
+    for triple in base_triples:
+        g.add(triple)
+    g.add((EG.scheck, EG.pcheck, URIRef(iri)))
+    assert len(g) == 3
+    dsg = g.de_skolemize()
+    if expected_bnode_value is None:
+        GraphHelper.assert_sets_equals(g, dsg)
+    else:
+        assert len(dsg) == len(g)
+        iset = GraphHelper.triple_or_quad_set(dsg)
+        logging.debug("iset = %s", iset)
+        assert iset.issuperset(base_triples)
+        check_triples = list(dsg.triples((EG.scheck, EG.pcheck, None)))
+        assert len(check_triples) == 1
+        bnode = check_triples[0][2]
+        logging.debug("bnode = %s, bnode_value = %s", bnode, f"{bnode}")
+        assert isinstance(bnode, BNode)
+        if isinstance(expected_bnode_value, str):
+            assert expected_bnode_value == f"{bnode}"
+        else:
+            assert expected_bnode_value.match(f"{bnode}") is not None

test/test_issues/test_issue1404.py

@@ -1,6 +1,5 @@
 from rdflib import FOAF, Graph, URIRef
 from rdflib.compare import isomorphic
-from rdflib.term import RDFLibGenid
 
 
 def test_skolem_de_skolem_roundtrip():
@@ -30,9 +29,9 @@ def test_skolem_de_skolem_roundtrip():
 
     skolemized_graph = graph.skolemize()
 
-    # Check the BNode is now an RDFLibGenid after skolemization.
+    # Check the BNode is now a URIRef after skolemization.
     skolem_bnode = skolemized_graph.value(**query)
-    assert type(skolem_bnode) == RDFLibGenid
+    assert type(skolem_bnode) == URIRef
 
     # Check that the original bnode id exists somewhere in the uri.
     assert bnode_id in skolem_bnode

test/test_issues/test_issue1808.py

@@ -0,0 +1,44 @@
+from rdflib import Graph
+from rdflib.term import BNode, URIRef, rdflib_skolem_genid
+
+
+def test():
+    """Test skolemised URI query retrieves expected results.
+
+    Issue: https://github.com/RDFLib/rdflib/issues/1808
+    """
+
+    g = Graph()
+    g.parse(data='[] <urn:prop> "val" .', format="turtle")
+    for s, p, o in g:
+        assert isinstance(s, BNode)
+
+    gs = g.skolemize()
+    for s, p, o in gs:
+        assert isinstance(s, URIRef) and s.__contains__(rdflib_skolem_genid)
+
+    query_with_iri = 'select ?p ?o {{ <{}> ?p ?o }}'.format(s)
+    query_for_all = 'select ?s ?p ?o { ?s ?p ?o }'
+
+    count = 0
+    for row in gs.query(query_with_iri):
+        count += 1
+    assert count == 1
+
+    count = 0
+    for row in gs.query(query_for_all):
+        count += 1
+    assert count == 1
+
+    gp = Graph()
+    gp.parse(data=gs.serialize(format='turtle'), format='turtle')
+
+    count = 0
+    for row in gp.query(query_with_iri):
+        count += 1
+    assert count == 1
+
+    count = 0
+    for row in gp.query(query_for_all):
+        count += 1
+    assert count == 1

test/test_skolem_genid.py

@@ -0,0 +1,17 @@
+from rdflib import URIRef
+from rdflib.term import Genid, RDFLibGenid
+
+
+def test_skolem_genid_and_rdflibgenid():
+    rdflib_genid = URIRef(
+        "http://rdflib.net/.well-known/genid/rdflib/N97c39b957bc444949a82793519348dc2"
+    )
+    custom_genid = URIRef(
+        "http://example.com/.well-known/genid/example/Ne864c0e3684044f381d518fdac652f2e"
+    )
+
+    assert RDFLibGenid._is_rdflib_skolem(rdflib_genid) is True
+    assert Genid._is_external_skolem(rdflib_genid) is True
+
+    assert RDFLibGenid._is_rdflib_skolem(custom_genid) is False
+    assert Genid._is_external_skolem(custom_genid) is True