Fixed bug when fetch variables contain output converters and a query is

re-executed (#271).

Author: anthony-tuininga

doc/src/release_notes.rst

@@ -15,6 +15,9 @@ Thin Mode Changes
 
 #)  Added support for using alternative event loop implementations like uvloop
     (`issue 276 <https://github.com/oracle/python-oracledb/issues/276>`__).
+#)  Fixed bug when fetch variables contain output converters and a query is
+    re-executed
+    (`issue 271 <https://github.com/oracle/python-oracledb/issues/271>`__).
 
 Common Changes
 ++++++++++++++

src/oracledb/impl/thin/messages.pyx

@@ -1,5 +1,5 @@
 #------------------------------------------------------------------------------
-# Copyright (c) 2020, 2023, Oracle and/or its affiliates.
+# Copyright (c) 2020, 2024, Oracle and/or its affiliates.
 #
 # This software is dual-licensed to you under the Universal Permissive License
 # (UPL) 1.0 as shown at https://oss.oracle.com/licenses/upl and Apache License
@@ -761,6 +761,7 @@ cdef class MessageWithData(Message):
         if self.error_info.num == TNS_ERR_NO_DATA_FOUND:
             self.error_info.num = 0
             cursor_impl._more_rows_to_fetch = False
+            cursor_impl._last_row_index = 0
             self.error_occurred = False
         elif self.error_info.num == TNS_ERR_ARRAY_DML_ERRORS:
             self.error_info.num = 0

tests/test_3600_outputtypehandler.py

@@ -1,5 +1,5 @@
 # -----------------------------------------------------------------------------
-# Copyright (c) 2021, 2023, Oracle and/or its affiliates.
+# Copyright (c) 2021, 2024, Oracle and/or its affiliates.
 #
 # This software is dual-licensed to you under the Universal Permissive License
 # (UPL) 1.0 as shown at https://oss.oracle.com/licenses/upl and Apache License
@@ -683,6 +683,44 @@ def type_handler(cursor, name, default_type, size, precision, scale):
             cursor.execute("select 1 from dual")
             self.assertEqual(cursor.fetchall(), [("1",)])
 
+    def test_3676_reexecute_no_rows(self):
+        "3676 - re-execute query with second fetch returning no rows"
+
+        self.cursor.execute("truncate table TestTempTable")
+        data = [(i + 1,) for i in range(5)]
+        self.cursor.executemany(
+            "insert into TestTempTable (IntCol) values (:1)", data
+        )
+        self.conn.commit()
+
+        def type_handler_1(cursor, metadata):
+            return cursor.var(
+                str,
+                arraysize=cursor.arraysize,
+                outconverter=lambda x: f"_{x}_",
+            )
+
+        def type_handler_2(cursor, metadata):
+            return cursor.var(
+                str,
+                arraysize=cursor.arraysize,
+                outconverter=lambda x: f"={x}=",
+            )
+
+        self.cursor.outputtypehandler = type_handler_1
+        self.cursor.arraysize = 6
+        self.cursor.prefetchrows = 6
+        sql = "select IntCol from TestTempTable where rownum <= :1"
+        self.cursor.execute(sql, [6])
+        expected_value = [(f"_{x}_",) for x, in data]
+        self.assertEqual(self.cursor.fetchall(), expected_value)
+
+        self.cursor.outputtypehandler = type_handler_2
+        self.cursor.prefetchrows = 2
+        self.cursor.arraysize = 2
+        self.cursor.execute(sql, [0])
+        self.assertEqual(self.cursor.fetchall(), [])
+
 
 if __name__ == "__main__":
     test_env.run_test_cases()