Fix SP returning NULL (closes pymssql#441).

Author: termim

ChangeLog.rst

@@ -7,7 +7,8 @@ Version 2.3.1 - 2024-      - Mikhail Terekhov
 General
 -------
 
-- Update FreeTDS to 1.4.22.
+- Fix SP returning NULL (closes #441).
+- Update FreeTDS to 1.4.22 (closes #895).
 - Require Cython>3.0.10.
 
 Version 2.3.0 - 2024-04-06 - Mikhail Terekhov

src/pymssql/_mssql.pyx

@@ -1823,13 +1823,16 @@ cdef class MSSQLStoredProcedure:
         # set the values in the parameters dictionary.
         if output_count:
             for i in xrange(1, output_count + 1):
+                value = None
                 with nogil:
                     type = dbrettype(self.dbproc, i)
                     param_name_bytes = dbretname(self.dbproc, i)
                     length = dbretlen(self.dbproc, i)
-                    data = dbretdata(self.dbproc, i)
+                    if length:
+                        data = dbretdata(self.dbproc, i)
 
-                value = self.conn.convert_db_value(data, type, length)
+                if length:
+                    value = self.conn.convert_db_value(data, type, length)
 
                 if strlen(param_name_bytes):
                     param_name = param_name_bytes.decode('utf-8')

tests/test_sprocs.py

@@ -113,6 +113,13 @@ def tearDown(self):
         self.pymssql.close()
         self.mssql.close()
 
+    def testBigIntNullIn(self):
+        input = None
+        proc = self.mssql.init_procedure('pymssqlTestBigInt')
+        proc.bind(input, _mssql.SQLINT8, '@ibigint', null=True)
+        proc.bind(None, _mssql.SQLINT8, '@obigint', output=True)
+        proc.execute()
+        self.assertEqual(input, proc.parameters['@obigint'])
 
     def testBigInt(self):
         input = 123456789
@@ -776,3 +783,40 @@ def test_callproc(self):
         res = self.cursor.fetchall()
         self.assertEqual(res, [('Tom',), ('Dick',), ('Harry',)])
 
+
+@pytest.mark.mssql_server_required
+class TestSPWithNULLResult(unittest.TestCase):
+    """
+    GH: #441
+    """
+
+    SP_NAME = 'SPWithANullResult'
+
+    def setUp(self):
+        self.mssql = mssqlconn()
+        self.pymssql = pymssqlconn()
+
+        self.mssql.execute_non_query("""
+        CREATE PROCEDURE [dbo].[%(spname)s]
+                @int_arg int output,
+                @varchar_arg varchar output
+        AS
+        BEGIN
+                SET @int_arg = null
+                SET @varchar_arg = null
+        END
+        """ % {'spname': self.SP_NAME})
+
+    def tearDown(self):
+        self.mssql.execute_non_query('DROP PROCEDURE [dbo].[%(spname)s]' % {'spname': self.SP_NAME})
+        self.pymssql.close()
+        self.mssql.close()
+
+    def testNull(self):
+        proc = self.mssql.init_procedure(self.SP_NAME)
+        proc.bind(None, _mssql.SQLINT8, '@int_arg', output=True)
+        proc.bind(None, _mssql.SQLVARCHAR, '@varchar_arg', output=True)
+        proc.execute()
+        self.assertIsNone(proc.parameters['@int_arg'])
+        self.assertIsNone(proc.parameters['@varchar_arg'])
+