fix(oss): return 404 when file large object is missing

apps/oss/serializers/file.py

@@ -9,6 +9,7 @@
 from common.constants.authentication_type import AuthenticationType
 from common.database_model_manage.database_model_manage import DatabaseModelManage
 from common.exception.app_exception import AppApiException, AppUnauthorizedFailed, NotFound404
+from django.db import DatabaseError
 from django.db.models import QuerySet
 from django.http import HttpResponse
 from django.utils.translation import gettext
@@ -299,8 +300,16 @@ def get(self, mk_file_auth=None, with_valid=True):
             file_type = file.file_name.split(".")[-1].lower()
             content_type = mime_types.get(file_type, 'application/octet-stream')
             encoded_filename = urllib.parse.quote(file.file_name)
-            # 获取文件内容
-            file_bytes = file.get_bytes()
+            # 获取文件内容。元数据还在但 PostgreSQL 大对象已丢失时，
+            # lo_get 会抛 DatabaseError（large object … does not exist），
+            # 不应以 500 把库原始报错透出给前端（#7356）。
+            try:
+                file_bytes = file.get_bytes()
+            except DatabaseError as e:
+                msg = str(e).lower()
+                if 'large object' in msg and 'does not exist' in msg:
+                    raise NotFound404(404, _('File content not found')) from e
+                raise
             file_size = len(file_bytes)
 
             response = None

apps/oss/tests.py

@@ -52,3 +52,47 @@ def test_get_url_retrieval_routes_pass_application_id(self):
             'chat_oss_retrieval',
             {'application_id': 'application-id'},
         )
+
+
+class MissingLargeObjectTests(SimpleTestCase):
+    """#7356: metadata exists but Postgres large object is gone → 404, not 500."""
+
+    def test_operate_get_maps_missing_large_object_to_404(self):
+        from unittest.mock import MagicMock, patch
+
+        from django.db import DatabaseError
+
+        from common.exception.app_exception import NotFound404
+        from oss.serializers.file import FileSerializer
+
+        operate = FileSerializer.Operate(data={'id': '00000000-0000-0000-0000-000000000001'})
+        self.assertTrue(operate.is_valid())
+
+        fake_file = MagicMock()
+        fake_file.file_name = 'pic.png'
+        fake_file.get_bytes.side_effect = DatabaseError('large object 90563 does not exist')
+
+        with patch('oss.serializers.file.QuerySet') as qs, patch('oss.serializers.file.auth'):
+            qs.return_value.filter.return_value.first.return_value = fake_file
+            with self.assertRaises(NotFound404) as ctx:
+                operate.get(with_valid=False)
+        self.assertEqual(ctx.exception.status_code, 404)
+
+    def test_operate_get_rethrows_unrelated_database_error(self):
+        from unittest.mock import MagicMock, patch
+
+        from django.db import DatabaseError
+
+        from oss.serializers.file import FileSerializer
+
+        operate = FileSerializer.Operate(data={'id': '00000000-0000-0000-0000-000000000001'})
+        self.assertTrue(operate.is_valid())
+
+        fake_file = MagicMock()
+        fake_file.file_name = 'pic.png'
+        fake_file.get_bytes.side_effect = DatabaseError('connection already closed')
+
+        with patch('oss.serializers.file.QuerySet') as qs, patch('oss.serializers.file.auth'):
+            qs.return_value.filter.return_value.first.return_value = fake_file
+            with self.assertRaises(DatabaseError):
+                operate.get(with_valid=False)