Add special handling for gYear and gYearMonth in _SpecificPythonToXSD…

…Rules

This should solve various issues that occur with hanlding of xsd:gYear
and xsd:gYearMonth values.

rdflib/term.py

@@ -1436,6 +1436,8 @@ def _parseBoolean(value):
 
 _OWL_RATIONAL = URIRef("http://www.w3.org/2002/07/owl#rational")
 _XSD_HEXBINARY = URIRef(_XSD_PFX + "hexBinary")
+_XSD_YEAR = URIRef(_XSD_PFX + "gYear")
+_XSD_YEARMONTH = URIRef(_XSD_PFX + "gYearMonth")
 # TODO: gYearMonth, gYear, gMonthDay, gDay, gMonth
 
 _NUMERIC_LITERAL_TYPES = (
@@ -1559,6 +1561,8 @@ def _castPythonToLiteral(obj, datatype):
 _SpecificPythonToXSDRules = [
     ((str, _XSD_HEXBINARY), hexlify),
     ((bytes, _XSD_HEXBINARY), hexlify),
+    ((date, _XSD_YEAR), lambda val: val.strftime("%04Y")),
+    ((date, _XSD_YEARMONTH), lambda val: val.strftime("%04Y-%02m")),
 ]
 
 XSDToPython = {

test/test_literal.py

@@ -1,7 +1,9 @@
 import unittest
+import datetime
 
 import rdflib  # needed for eval(repr(...)) below
 from rdflib.term import Literal, URIRef, _XSD_DOUBLE, bind, _XSD_BOOLEAN
+from rdflib.namespace import XSD
 
 
 def uformat(s):
@@ -188,5 +190,73 @@ def unlexify(s):
         self.assertEqual(specific_l.datatype, datatype)
 
 
+class TestXsdLiterals(unittest.TestCase):
+    def test_make_literals(self):
+        """
+        Tests literal construction.
+        """
+        inputs = [
+            # these literals do not get conerted to python types
+            ("ABCD", XSD.integer, None),
+            ("ABCD", XSD.gYear, None),
+            ("-10000", XSD.gYear, None),
+            ("-1921-00", XSD.gYearMonth, None),
+            ("1921-00", XSD.gMonthDay, None),
+            ("1921-13", XSD.gMonthDay, None),
+            ("-1921-00", XSD.gMonthDay, None),
+            ("10", XSD.gDay, None),
+            ("-1", XSD.gDay, None),
+            ("0000", XSD.gYear, None),
+            ("0000-00-00", XSD.date, None),
+            # these literals get converted to python types
+            ("1921-05-01", XSD.date, datetime.date),
+            ("1921-05-01T00:00:00", XSD.dateTime, datetime.datetime),
+            ("1921-05", XSD.gYearMonth, datetime.date),
+            ("0001-01", XSD.gYearMonth, datetime.date),
+            ("0001-12", XSD.gYearMonth, datetime.date),
+            ("2002-01", XSD.gYearMonth, datetime.date),
+            ("9999-01", XSD.gYearMonth, datetime.date),
+            ("9999-12", XSD.gYearMonth, datetime.date),
+            ("1921", XSD.gYear, datetime.date),
+            ("2000", XSD.gYear, datetime.date),
+            ("0001", XSD.gYear, datetime.date),
+            ("9999", XSD.gYear, datetime.date),
+            ("1982", XSD.gYear, datetime.date),
+            ("2002", XSD.gYear, datetime.date),
+            ("1921-05-01T00:00:00+00:30", XSD.dateTime, datetime.datetime),
+            ("1921-05-01T00:00:00-00:30", XSD.dateTime, datetime.datetime),
+        ]
+        self.check_make_literals(inputs)
+
+    @unittest.expectedFailure
+    def test_make_literals_ki(self):
+        """
+        Known issues with literal construction.
+        """
+        inputs = [
+            ("1921-01Z", XSD.gYearMonth, datetime.date),
+            ("1921Z", XSD.gYear, datetime.date),
+            ("1921-00", XSD.gYearMonth, datetime.date),
+            ("1921-05-01Z", XSD.date, datetime.date),
+            ("1921-05-01+00:30", XSD.date, datetime.date),
+            ("1921-05-01+00:30", XSD.date, datetime.date),
+            ("1921-05-01+00:00", XSD.date, datetime.date),
+            ("1921-05-01+00:00", XSD.date, datetime.date),
+            ("1921-05-01T00:00:00Z", XSD.dateTime, datetime.datetime),
+        ]
+        self.check_make_literals(inputs)
+
+    def check_make_literals(self, inputs):
+        for literal_pair in inputs:
+            (lexical, type, value_cls) = literal_pair
+            with self.subTest(f"tesing {literal_pair}"):
+                literal = Literal(lexical, datatype=type)
+                if value_cls is not None:
+                    self.assertIsInstance(literal.value, value_cls)
+                else:
+                    self.assertIsNone(literal.value)
+                self.assertEqual(lexical, f"{literal}")
+
+
 if __name__ == "__main__":
     unittest.main()

test/test_parser.py

@@ -44,5 +44,47 @@ def testNoPathWithHash(self):
         self.assertEqual(type, RDFS.Class)
 
 
+class TestGitHubIssues(unittest.TestCase):
+    def test_issue_1228_a(self):
+        data = """
+        PREFIX sdo: <https://schema.org/>
+        PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
+
+        <x:> sdo:startDate "1982"^^xsd:gYear .
+        """
+
+        g = Graph().parse(data=data, format="ttl")
+        self.assertNotIn("1982-01-01", data)
+        self.assertNotIn("1982-01-01", g.serialize(format="ttl"))
+
+    def test_issue_1228_b(self):
+        data = """\
+<?xml version="1.0" encoding="UTF-8"?>
+    <rdf:RDF
+    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+    xmlns:sdo="https://schema.org/"
+    >
+    <rdf:Description rdf:about="x:">
+        <sdo:startDate
+            rdf:datatype="http://www.w3.org/2001/XMLSchema#gYear">1982</sdo:startDate>
+    </rdf:Description>
+</rdf:RDF>"""
+
+        g = Graph().parse(data=data, format="xml")
+        self.assertNotIn("1982-01-01", data)
+        self.assertNotIn("1982-01-01", g.serialize(format="xml"))
+
+    def test_issue_806(self):
+        data = (
+            "<http://dbpedia.org/resource/Australian_Labor_Party> "
+            "<http://dbpedia.org/ontology/formationYear> "
+            '"1891"^^<http://www.w3.org/2001/XMLSchema#gYear> .'
+        )
+        g = Graph()
+        g.parse(data=data, format="nt")
+        for _, _, o in g:
+            self.assertNotIn("1891-01-01", o.n3())
+
+
 if __name__ == "__main__":
     unittest.main()