Fix order (#4087)

* Fix order

* Update header

* Update changelog

* Add Prefetch
Co-authored-by: NNikita Manovich <nikita.manovich@intel.com>

CHANGELOG.md

@@ -47,6 +47,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added information to export CVAT_HOST when performing local installation for accessing over network (<https://github.com/openvinotoolkit/cvat/pull/4014>)
 - Fixed possible color collisions in the generated colormap (<https://github.com/openvinotoolkit/cvat/pull/4007>)
 - Original pdf file is deleted when using share (<https://github.com/openvinotoolkit/cvat/pull/3967>)
+- Order in an annotation file(<https://github.com/openvinotoolkit/cvat/pull/4087>)
 - Fixed task data upload progressbar (<https://github.com/openvinotoolkit/cvat/pull/4134>)
 
 ### Security

cvat/apps/dataset_manager/bindings.py

 
-# Copyright (C) 2019-2020 Intel Corporation
+# Copyright (C) 2019-2021 Intel Corporation
 #
 # SPDX-License-Identifier: MIT
 

cvat/apps/dataset_manager/task.py

@@ -7,6 +7,7 @@ from collections import OrderedDict
 from enum import Enum
 
 from django.db import transaction
+from django.db.models.query import Prefetch
 from django.utils import timezone
 
 from cvat.apps.engine import models, serializers
@@ -547,7 +548,9 @@ class JobAnnotation:
 
 class TaskAnnotation:
     def __init__(self, pk):
-        self.db_task = models.Task.objects.prefetch_related("data__images").get(id=pk)
+        self.db_task = models.Task.objects.prefetch_related(
+            Prefetch('data__images', queryset=models.Image.objects.order_by('frame'))
+        ).get(id=pk)
 
         # Postgres doesn't guarantee an order by default without explicit order_by
         self.db_jobs = models.Job.objects.select_related("segment").filter(segment__task_id=pk).order_by('id')