Fixed #28859 -- Made Oracle backend raise DatabaseError if "no data found" exception is hidden by the Oracle OCI library.

Thanks Tim Graham for the review and Jani Tiainen for the report.

django/db/backends/oracle/operations.py

@@ -5,6 +5,7 @@ import uuid
 from django.conf import settings
 from django.db.backends.base.operations import BaseDatabaseOperations
 from django.db.backends.utils import strip_quotes, truncate_name
+from django.db.utils import DatabaseError
 from django.utils import timezone
 from django.utils.encoding import force_bytes
 
@@ -217,7 +218,14 @@ END;
         return " DEFERRABLE INITIALLY DEFERRED"
 
     def fetch_returned_insert_id(self, cursor):
-        return int(cursor._insert_id_var.getvalue())
+        try:
+            return int(cursor._insert_id_var.getvalue())
+        except TypeError:
+            raise DatabaseError(
+                'The database did not return a new row id. Probably "ORA-1403: '
+                'no data found" was raised internally but was hidden by the '
+                'Oracle OCI library (see https://code.djangoproject.com/ticket/28859).'
+            )
 
     def field_cast_sql(self, db_type, internal_type):
         if db_type and db_type.endswith('LOB'):

tests/backends/oracle/tests.py

@@ -2,6 +2,10 @@ import unittest
 
 from django.db import connection
 from django.db.models.fields import BooleanField, NullBooleanField
+from django.db.utils import DatabaseError
+from django.test import TransactionTestCase
+
+from ..models import Square
 
 
 @unittest.skipUnless(connection.vendor == 'oracle', 'Oracle tests')
@@ -61,3 +65,32 @@ class Tests(unittest.TestCase):
             with self.subTest(field=field):
                 field.set_attributes_from_name('is_nice')
                 self.assertIn('"IS_NICE" IN (0,1)', field.db_check(connection))
+
+
+@unittest.skipUnless(connection.vendor == 'oracle', 'Oracle tests')
+class HiddenNoDataFoundExceptionTest(TransactionTestCase):
+    available_apps = ['backends']
+
+    def test_hidden_no_data_found_exception(self):
+        # "ORA-1403: no data found" exception is hidden by Oracle OCI library
+        # when an INSERT statement is used with a RETURNING clause (see #28859).
+        with connection.cursor() as cursor:
+            # Create trigger that raises "ORA-1403: no data found".
+            cursor.execute("""
+                CREATE OR REPLACE TRIGGER "TRG_NO_DATA_FOUND"
+                AFTER INSERT ON "BACKENDS_SQUARE"
+                FOR EACH ROW
+                BEGIN
+                    RAISE NO_DATA_FOUND;
+                END;
+            """)
+        try:
+            with self.assertRaisesMessage(DatabaseError, (
+                'The database did not return a new row id. Probably "ORA-1403: '
+                'no data found" was raised internally but was hidden by the '
+                'Oracle OCI library (see https://code.djangoproject.com/ticket/28859).'
+            )):
+                Square.objects.create(root=2, square=4)
+        finally:
+            with connection.cursor() as cursor:
+                cursor.execute('DROP TRIGGER "TRG_NO_DATA_FOUND"')