Fixes #1043.

rdflib/term.py

@@ -1259,10 +1259,9 @@ def _literal_n3(self, use_plain=False, qname_callback=None):
                     return sub("\\.?0*e", "e", "%e" % float(self))
                 elif self.datatype == _XSD_DECIMAL:
                     s = "%s" % self
-                    if "." not in s:
+                    if "." not in s and "e" not in s and "E" not in s:
                         s += ".0"
                     return s
-
                 elif self.datatype == _XSD_BOOLEAN:
                     return ("%s" % self).lower()
                 else:

test/test_issue1043.py

@@ -0,0 +1,33 @@
+import decimal
+import unittest
+import io
+import sys
+
+from rdflib import Graph, Namespace, XSD, RDFS, Literal
+
+
+class TestIssue1043(unittest.TestCase):
+
+    def test_issue_1043(self):
+        expected = """@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+
+<http://example.org/number> rdfs:label 4e-08 .
+
+
+"""
+        capturedOutput = io.StringIO()
+        sys.stdout = capturedOutput
+        g = Graph()
+        g.bind('xsd', XSD)
+        g.bind('rdfs', RDFS)
+        n = Namespace("http://example.org/")
+        g.add((n.number, RDFS.label, Literal(0.00000004, datatype=XSD.decimal)))
+        print(g.serialize(format="turtle").decode("utf-8"))
+        sys.stdout = sys.__stdout__
+        self.assertEqual(capturedOutput.getvalue(), expected)
+
+
+
+if __name__ == "__main__":
+    unittest.main()