Fixed bug when fetching nested cursors.

Author: anthony-tuininga

doc/src/release_notes.rst

@@ -38,6 +38,7 @@ Thin Mode Changes
 #)  Fixed bug when connecting to an AC-enabled service
     (`issue 476 <https://github.com/oracle/python-oracledb/issues/476>`__).
 #)  Fixed bug when using temporary LOBs with implicit pooling.
+#)  Fixed bug when fetching nested cursors.
 
 Thick Mode Changes
 ++++++++++++++++++

src/oracledb/impl/thin/messages/base.pyx

@@ -896,6 +896,8 @@ cdef class MessageWithData(Message):
             column_value = self._create_cursor_from_describe(buf, column_value)
             cursor_impl = column_value._impl
             buf.read_ub2(&cursor_impl._statement._cursor_id)
+            if self.in_fetch:
+                cursor_impl._statement._is_nested = True
         elif ora_type_num in (ORA_TYPE_NUM_CLOB,
                               ORA_TYPE_NUM_BLOB,
                               ORA_TYPE_NUM_BFILE):

src/oracledb/impl/thin/statement.pyx

@@ -1,5 +1,5 @@
 #------------------------------------------------------------------------------
-# Copyright (c) 2020, 2024, Oracle and/or its affiliates.
+# Copyright (c) 2020, 2025, 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
@@ -305,6 +305,7 @@ cdef class Statement:
         bint _no_prefetch
         bint _requires_define
         bint _return_to_cache
+        bint _is_nested
         bint _in_use
 
     cdef Statement copy(self):

src/oracledb/impl/thin/statement_cache.pyx

@@ -1,5 +1,5 @@
 #------------------------------------------------------------------------------
-# Copyright (c) 2024, Oracle and/or its affiliates.
+# Copyright (c) 2024, 2025, 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
@@ -45,7 +45,7 @@ cdef class StatementCache:
         Add the statement's cursor to the list of cursors that need to be
         closed.
         """
-        if stmt._cursor_id != 0:
+        if stmt._cursor_id != 0 and not stmt._is_nested:
             self._cursors_to_close[self._num_cursors_to_close] = \
                     stmt._cursor_id
             self._num_cursors_to_close += 1

tests/test_1300_cursor_var.py

@@ -459,6 +459,47 @@ def test_1319(self):
         with self.assertRaisesFullCode("DPY-3027"):
             self.cursor.execute(sql, [ref_cursor])
 
+    def test_1320(self):
+        "1320 - test fetching nested cursors repeatedly"
+        sql = """
+            select
+                s.Description,
+                cursor(select 'Nested String for ' || s.Description from dual)
+            from
+                (
+                    select 'Top Level String 1' as Description
+                    from dual
+                    union all
+                    select 'Top Level String 2'
+                    from dual
+                    union all
+                    select 'Top Level String 3'
+                    from dual
+                    union all
+                    select 'Top Level String 4'
+                    from dual
+                    union all
+                    select 'Top Level String 5'
+                    from dual
+                ) s"""
+
+        for i in range(3):
+            with self.conn.cursor() as cursor:
+                cursor.arraysize = 10
+                cursor.execute(sql)
+                desc, nested1 = cursor.fetchone()
+                self.assertEqual(desc, "Top Level String 1")
+                nested_rows = nested1.fetchall()
+                self.assertEqual(
+                    nested_rows, [("Nested String for Top Level String 1",)]
+                )
+                desc, nested2 = cursor.fetchone()
+                self.assertEqual(desc, "Top Level String 2")
+                nested_rows = nested2.fetchall()
+                self.assertEqual(
+                    nested_rows, [("Nested String for Top Level String 2",)]
+                )
+
 
 if __name__ == "__main__":
     test_env.run_test_cases()

tests/test_6300_cursor_other_async.py

@@ -872,6 +872,47 @@ async def test_6351(self):
         await self.cursor.execute("select * from TestJsonCols order by IntCol")
         self.assertEqual(await self.cursor.fetchall(), expected_data)
 
+    async def test_6352(self):
+        "6352 - test fetching nested cursors repeatedly"
+        sql = """
+            select
+                s.Description,
+                cursor(select 'Nested String for ' || s.Description from dual)
+            from
+                (
+                    select 'Top Level String 1' as Description
+                    from dual
+                    union all
+                    select 'Top Level String 2'
+                    from dual
+                    union all
+                    select 'Top Level String 3'
+                    from dual
+                    union all
+                    select 'Top Level String 4'
+                    from dual
+                    union all
+                    select 'Top Level String 5'
+                    from dual
+                ) s"""
+
+        for i in range(3):
+            with self.conn.cursor() as cursor:
+                cursor.arraysize = 10
+                await cursor.execute(sql)
+                desc, nested1 = await cursor.fetchone()
+                self.assertEqual(desc, "Top Level String 1")
+                nested_rows = await nested1.fetchall()
+                self.assertEqual(
+                    nested_rows, [("Nested String for Top Level String 1",)]
+                )
+                desc, nested2 = await cursor.fetchone()
+                self.assertEqual(desc, "Top Level String 2")
+                nested_rows = await nested2.fetchall()
+                self.assertEqual(
+                    nested_rows, [("Nested String for Top Level String 2",)]
+                )
+
 
 if __name__ == "__main__":
     test_env.run_test_cases()