Fixed bug when fetching LOBs after an exception has been raised (#338).

Author: anthony-tuininga

doc/src/release_notes.rst

@@ -20,6 +20,8 @@ Thin Mode Changes
 #)  Fixed bug when a :ref:`DbObject <dbobject>` instance contains an attribute
     of type ``SYS.XMLTYPE``
     (`issue 336 <https://github.com/oracle/python-oracledb/issues/336>`__).
+#)  Fixed bug when fetching LOBs after an exception has been raised
+    (`issue 338 <https://github.com/oracle/python-oracledb/issues/338>`__).
 #)  Fixed bug in statement cache when the maximum number of cursors is unknown
     due to the database not being open.
 #)  Fixed bug in handling redirect data with small SDU sizes.

src/oracledb/impl/thin/messages.pyx

@@ -738,11 +738,10 @@ cdef class MessageWithData(Message):
             if prev_fetch_var_impls is not None \
                     and i < len(prev_fetch_var_impls):
                 self._adjust_fetch_info(prev_fetch_var_impls[i], fetch_info)
-            if not stmt._no_prefetch and \
-                    fetch_info.dbtype._ora_type_num in (TNS_DATA_TYPE_BLOB,
-                                                        TNS_DATA_TYPE_CLOB,
-                                                        TNS_DATA_TYPE_JSON,
-                                                        TNS_DATA_TYPE_VECTOR):
+            if fetch_info.dbtype._ora_type_num in (TNS_DATA_TYPE_BLOB,
+                                                   TNS_DATA_TYPE_CLOB,
+                                                   TNS_DATA_TYPE_JSON,
+                                                   TNS_DATA_TYPE_VECTOR):
                 stmt._requires_define = True
                 stmt._no_prefetch = True
             cursor_impl._create_fetch_var(conn, self.cursor, type_handler,
@@ -773,6 +772,8 @@ cdef class MessageWithData(Message):
             cursor_impl._statement._cursor_id = self.error_info.cursor_id
         if not cursor_impl._statement._is_plsql and not self.in_fetch:
             cursor_impl.rowcount = self.error_info.rowcount
+        elif self.in_fetch and self.row_index > 0:
+            cursor_impl._statement._requires_define = False
         cursor_impl._lastrowid = self.error_info.rowid
         cursor_impl._batcherrors = self.error_info.batcherrors
         if self.batcherrors and cursor_impl._batcherrors is None:
@@ -781,6 +782,7 @@ cdef class MessageWithData(Message):
             self.error_info.num = 0
             cursor_impl._more_rows_to_fetch = False
             cursor_impl._last_row_index = 0
+            cursor_impl._statement._requires_define = False
             self.error_occurred = False
         elif self.error_info.num == TNS_ERR_ARRAY_DML_ERRORS:
             self.error_info.num = 0

tests/test_4300_cursor_other.py

@@ -977,6 +977,20 @@ def test_4365(self):
         with self.assertRaisesFullCode("DPY-2045"):
             self.cursor.arraysize = "not valid"
 
+    def test_4366(self):
+        "4366 - test fetching LOBs after an error"
+        sql = """
+            select
+                to_clob(:val),
+                1 / (dbms_lob.getlength(to_clob(:val)) - 1)
+            from dual"""
+        with self.assertRaisesFullCode("ORA-01476"):
+            self.cursor.execute(sql, val="a")
+        self.cursor.execute(sql, val="bb")
+        lob, num_val = self.cursor.fetchone()
+        self.assertEqual(lob.read(), "bb")
+        self.assertEqual(num_val, 1)
+
 
 if __name__ == "__main__":
     test_env.run_test_cases()

tests/test_6300_cursor_other_async.py

@@ -844,6 +844,20 @@ async def test_6347(self):
         }
         self.assertEqual(column_2.annotations, expected_annotations)
 
+    async def test_6348(self):
+        "6348 - test fetching LOBs after an error"
+        sql = """
+            select
+                to_clob(:val),
+                1 / (dbms_lob.getlength(to_clob(:val)) - 1)
+            from dual"""
+        with self.assertRaisesFullCode("ORA-01476"):
+            await self.cursor.execute(sql, val="a")
+        await self.cursor.execute(sql, val="bb")
+        lob, num_val = await self.cursor.fetchone()
+        self.assertEqual(await lob.read(), "bb")
+        self.assertEqual(num_val, 1)
+
 
 if __name__ == "__main__":
     test_env.run_test_cases()