In order to support a <null> type column being returned from

engine.  A TypeObject is needed instead of returning None.  As
None is used to verify that the type returned is in the TYPEMAP.

cursor.execute('select NULL from DUAL')

fails without this change.  There are other cases where a user might
explictly return NULL in place of an actual value.  Say in a view such
as INFORMATION_SCHEMA.COLUMNS where we don't support DOMAIN_NAME column.

The above example was added to tests/nuodb_types_test.py

Author: butson

pynuodb/datatype.py

@@ -154,8 +154,9 @@ def __cmp__(self, other):
 NUMBER = TypeObject(int, decimal.Decimal)
 DATETIME = TypeObject(Timestamp, Date, Time)
 ROWID = TypeObject()
+NULL = TypeObject(None)
 
-TYPEMAP = {"<null>": None,
+TYPEMAP = {"<null>": NULL,
            "string": STRING,
            "char": STRING,
            "varchar": STRING,

tests/nuodb_types_test.py

@@ -112,3 +112,16 @@ def test_datetime_types(self):
         assert row[1] == datetime.time(5, 44, 33, 221100)
         assert row[2] == datetime.datetime(2000, 1, 1, 5, 44, 33, 221100)
         assert row[3] == datetime.datetime(2000, 1, 1, 5, 44, 33, 221100)
+
+    def test_null_type(self):
+        con = self._connect()
+        cursor = con.cursor()
+
+        null_type = self.driver.TypeObjectFromNuodb('<null>')
+
+        cursor.execute("SELECT NULL from dual")
+        row = cursor.fetchone()
+
+        assert len(row) == 1
+        assert cursor.description[0][1] == null_type
+        assert row[0] is None