SPARQLStore does not transform Literal('') into Literal('None') anymo…

…re, fixes RDFLib#457

rdflib/plugins/stores/sparqlstore.py

@@ -129,17 +129,18 @@ def CastToTerm(node):
     elif node.tag == '{%s}uri' % SPARQL_NS:
         return URIRef(node.text)
     elif node.tag == '{%s}literal' % SPARQL_NS:
+        value = node.text if node.text is not None else ''
         if 'datatype' in node.attrib:
             dT = URIRef(node.attrib['datatype'])
             if False:  # not node.xpath('*'):
                 return Literal('', datatype=dT)
             else:
-                return Literal(node.text, datatype=dT)
+                return Literal(value, datatype=dT)
         elif '{http://www.w3.org/XML/1998/namespace}lang' in node.attrib:
-            return Literal(node.text, lang=node.attrib[
+            return Literal(value, lang=node.attrib[
                 "{http://www.w3.org/XML/1998/namespace}lang"])
         else:
-            return Literal(node.text)
+            return Literal(value)
     else:
         raise Exception('Unknown answer type')
 

test/test_issue457.py

@@ -0,0 +1,13 @@
+# test for https://github.com/RDFLib/rdflib/issues/457
+
+import io
+from xml.etree import ElementTree
+
+import rdflib
+from rdflib.plugins.stores.sparqlstore import CastToTerm
+
+s = """<ns0:literal xmlns:ns0="http://www.w3.org/2005/sparql-results#" />"""
+node = ElementTree.parse(io.BytesIO(s)).getroot()
+term = CastToTerm(node)
+assert term  == rdflib.Literal(''), repr(term)
+