PyTorch adapter: fix loading tasks that have already been cached (#6396)

<!-- Raise an issue to propose your change
(https://github.com/opencv/cvat/issues).
It helps to avoid duplication of efforts from multiple independent
contributors.
Discuss your ideas with maintainers to be sure that changes will be
approved and merged.
Read the [Contribution
guide](https://opencv.github.io/cvat/docs/contributing/). -->

<!-- Provide a general summary of your changes in the Title above -->

### Motivation and context
<!-- Why is this change required? What problem does it solve? If it
fixes an open
issue, please link to the issue here. Describe your changes in detail,
add
screenshots. -->
This was broken in 4fc494f.

Add a test to cover this case.

Fixes #6047.

CHANGELOG.md

@@ -28,6 +28,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added missed auto_add argument to Issue model (<https://github.com/opencv/cvat/pull/6364>)
 - \[API\] Performance of several API endpoints (<https://github.com/opencv/cvat/pull/6340>)
 - \[API\] Invalid schema for the owner field in several endpoints (<https://github.com/opencv/cvat/pull/6343>)
+- \[SDK\] Loading tasks that have been cached with the PyTorch adapter
+  (<https://github.com/opencv/cvat/issues/6047>)
 
 ### Security
 - TDB

cvat-sdk/cvat_sdk/pytorch/caching.py

@@ -159,7 +159,7 @@ def _initialize_task_dir(self, task: Task) -> None:
             if task_dir.exists():
                 shutil.rmtree(task_dir)
         else:
-            if saved_task.updated_date < task.updated_date:
+            if saved_task.api_model.updated_date < task.updated_date:
                 self._logger.info(
                     f"Task {task.id} has been updated on the server since it was cached; purging the cache"
                 )

tests/python/sdk/test_pytorch.py

@@ -7,7 +7,8 @@
 import os
 from logging import Logger
 from pathlib import Path
-from typing import Tuple
+from typing import Container, Tuple
+from urllib.parse import urlparse
 
 import pytest
 from cvat_sdk import Client, models
@@ -46,11 +47,18 @@ def _common_setup(
         api_client.configuration.logger[k] = logger
 
 
-def _disable_api_requests(monkeypatch: pytest.MonkeyPatch) -> None:
-    def disabled_request(*args, **kwargs):
-        raise RuntimeError("Disabled!")
+def _restrict_api_requests(
+    monkeypatch: pytest.MonkeyPatch, allow_paths: Container[str] = ()
+) -> None:
+    original_request = RESTClientObject.request
 
-    monkeypatch.setattr(RESTClientObject, "request", disabled_request)
+    def restricted_request(self, method, url, *args, **kwargs):
+        parsed_url = urlparse(url)
+        if parsed_url.path in allow_paths:
+            return original_request(self, method, url, *args, **kwargs)
+        raise RuntimeError("Disallowed!")
+
+    monkeypatch.setattr(RESTClientObject, "request", restricted_request)
 
 
 @pytest.mark.skipif(cvatpt is None, reason="PyTorch dependencies are not installed")
@@ -246,7 +254,7 @@ def test_offline(self, monkeypatch: pytest.MonkeyPatch):
 
         fresh_samples = list(dataset)
 
-        _disable_api_requests(monkeypatch)
+        _restrict_api_requests(monkeypatch)
 
         dataset = cvatpt.TaskVisionDataset(
             self.client,
@@ -258,6 +266,44 @@ def test_offline(self, monkeypatch: pytest.MonkeyPatch):
 
         assert fresh_samples == cached_samples
 
+    def test_update(self, monkeypatch: pytest.MonkeyPatch):
+        dataset = cvatpt.TaskVisionDataset(
+            self.client,
+            self.task.id,
+        )
+
+        # Recreating the dataset should only result in minimal requests.
+        _restrict_api_requests(
+            monkeypatch, allow_paths={f"/api/tasks/{self.task.id}", "/api/labels"}
+        )
+
+        dataset = cvatpt.TaskVisionDataset(
+            self.client,
+            self.task.id,
+        )
+
+        assert dataset[5][1].annotations.tags[0].label_id == self.label_ids[0]
+
+        # After an update, the annotations should be redownloaded.
+        monkeypatch.undo()
+
+        self.task.update_annotations(
+            models.PatchedLabeledDataRequest(
+                tags=[
+                    models.LabeledImageRequest(
+                        id=dataset[5][1].annotations.tags[0].id, frame=5, label_id=self.label_ids[1]
+                    ),
+                ]
+            )
+        )
+
+        dataset = cvatpt.TaskVisionDataset(
+            self.client,
+            self.task.id,
+        )
+
+        assert dataset[5][1].annotations.tags[0].label_id == self.label_ids[1]
+
 
 @pytest.mark.skipif(cvatpt is None, reason="PyTorch dependencies are not installed")
 class TestProjectVisionDataset:
@@ -401,7 +447,7 @@ def test_offline(self, monkeypatch: pytest.MonkeyPatch):
 
         fresh_samples = list(dataset)
 
-        _disable_api_requests(monkeypatch)
+        _restrict_api_requests(monkeypatch)
 
         dataset = cvatpt.ProjectVisionDataset(
             self.client,