[ENH] V1 → V2 API Migration - Tasks by satvshr · Pull Request #1611 · openml/openml-python

satvshr · Jan 9, 2026

Metadata

Reference Issue: stacks on [ENH] V1 → V2 API Migration - core structure #1576, fixes [ENH] V1 → V2 API Migration - tasks #1621
New Tests Added: No
Documentation Updated: No

codecov-commenter · Jan 9, 2026

Codecov Report

❌ Patch coverage is 13.37209% with 149 lines in your changes missing coverage. Please review.
✅ Project coverage is 27.30%. Comparing base (ec3ed63) to head (9a752eb).

Files with missing lines	Patch %	Lines
openml/_api/resources/task.py	10.63%	126 Missing ⚠️
openml/tasks/task.py	20.00%	12 Missing ⚠️
openml/tasks/functions.py	8.33%	11 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1611       +/-   ##
===========================================
- Coverage   54.71%   27.30%   -27.42%     
===========================================
  Files          61       61               
  Lines        5086     5102       +16     
===========================================
- Hits         2783     1393     -1390     
- Misses       2303     3709     +1406

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geetu040

From a high-level review, I noticed a few points that need adjustment:

Caching can likely be removed from the SDK, since these concerns should be handled by the base client.
I don't see the api_context being used in tasks/functions, so it's not clear to me how the SDK is actually using the new API interface here.
Instead of moving entire methods out of tasks/functions.py, it would be better to stick to the goal of minimal SDK changes while enabling v2 support.
API calls should be updated at the specific root functions (for example _get_task_description, OpenMLTask._download_split).
For listing tasks, please follow the approach discussed in #1575 comment.

examples/Advanced/fetch_evaluations_tutorial.py

geetu040

I have left some comments, please take a look and make sure the signature of all methods in TasksAPI, TasksV1 and TasksV2 stay same.

openml/_api/resources/base.py

openml/_api/resources/tasks.py

openml/tasks/functions.py

satvshr · Jan 16, 2026

@geetu040 I will explain the confusion I am facing to the best of my abilities, and I do feel communicating on the PR threads is yielding no results, hence I will just put everything here:

Over here you say the base class should have v1 functions like list, delete, and create. This means to me that all V1 related functions should be moved from functions.py to TasksV1 (from SDK to resources) and calls inside functions.py should be replaced with calls to api_context.backend.task.method. Over here, you say something similar, stating that TasksV1, V2, and TasksAPI should have the same function signatures.
Over here and here you mention that we should try to keep most of the code in SDK and not resources (contradictory to point 1).
Completely contrary to point 1 you mention get_tasks along with create_task and delete_task should stay in sdk over here.

I seem to be getting 2 contradictory messages from your end which is where the confusion arises.

geetu040 · Jan 19, 2026

I seem to be getting 2 contradictory messages from your end which is where the confusion arises.

I don't feel confused with the picture I have in my mind, I think I need to explain it even better. I'll try to document each method in detail what should be moved and what should stay.

satvshr · Jan 19, 2026

Kindly resolve the comments which have been solved, it would be easier to navigate!

geetu040 · Jan 19, 2026

Kindly resolve the comments which have been solved, it would be easier to navigate!

It doesn't look like I have the typical "Resolve" button.

Edit: It's visible in the "Files changed" section, I'll resolve them there.

geetu040

Really nice, the code is in a better shape now. Many lines have been removed in the functions.py which seem fine but I'll take a deeper look. In other comments mostly some cleaning is required.

openml/tasks/task.py

geetu040 · Jan 20, 2026

openml/tasks/task.py

we have an api call in _download_split, what do you think about that? also does it relate with the datasets PR?

we have an api call in _download_split, what do you think about that?

I remember you and Shrivaths discussing cache paths for V1 and V2 and I think the understanding was that the paths would differ, if that is the case, we should change this later on and leave it as it is right now.

also does it relate with the datasets PR?

Only the get_dataset part, hence the Shrivaths comment

geetu040 · Jan 20, 2026

openml/_api/resources/tasks.py

this looks really good and clean now, just one open thread which needs discussion now: #1611 (comment)

If you agreed with my approach, can we not close that too?

openml/_api/resources/base.py

geetu040

sdk code look good so far, please take a look at #1575 (comment) and make changes accordingly where needed.
all tests (existing and new) should pass to make sure we are retaining the original functionality of the sdk

geetu040 · Jan 30, 2026

openml/_api/resources/tasks.py

+        task_type: TaskType | int | None = None,
+        **kwargs: Any,
+    ) -> pd.DataFrame:
+        raise NotImplementedError("Task listing is not available in API v2 yet.")


see point 8 in #1575 (comment)

geetu040 · Jan 30, 2026

openml/tasks/functions.py

    return tasks


-@openml.utils.thread_safe_if_oslo_installed


see point 3 in #1575 (comment)

geetu040 · Jan 30, 2026

openml/tasks/task.py



-class OpenMLTask(OpenMLBase):
+class OpenMLTask(OpenMLBase, ResourceAPI):


should not inherit ResourceAPI

geetu040 · Jan 30, 2026

openml/tasks/task.py

-                source=str(split_url),
-                output_path=str(cache_file),
-            )
+            self._http.download(url=str(split_url), file_name="datasplits.arff")


use api_context.backend.task.[something] here

How am I supposed to do that? download is a method in the HTTPClient.

Still this should be under a method now called openml._backend.task.[something] and then we can take this problem to TaskV1.[something].

I see this function depends on download of HTTPClient, I'll either add that method in the core PR or we can plan to merge datasets PR before this.

Will be moving this to TaskAPI after discussion.

geetu040 · Jan 30, 2026

openml/tasks/functions.py

-        raise NotImplementedError(
-            f"Task type ID {task_type:d} is not supported. "
-            f"Supported task type IDs: {TaskType.SUPERVISED_CLASSIFICATION.value},"
-            f"{TaskType.SUPERVISED_REGRESSION.value}, "
-            f"{TaskType.CLUSTERING.value}, {TaskType.LEARNING_CURVE.value}. "
-            f"Please refer to the TaskType enum for valid task type identifiers."
-        )
+        raise NotImplementedError(f"Task type {task_type:d} not supported.")


let's keep it as it was

This reverts commit fd43c48.

geetu040

update with #1576 (comment)

identified in https://github.com/openml/openml-python/actions/runs/23148612114/job/67243650521?pr=1609

identified in https://github.com/openml/openml-python/actions/runs/23430963986/job/68156944423?pr=1576

geetu040

the tests are failing because the cache path has changed

old: tests/files/org/openml/test/tasks/1882
new: tests/files/org/openml/test/api/v1/xml/task/1882

Let's discuss this on slack and see how we proceed with this change.

geetu040

Please see #1619 (review) regarding changed cache path

geetu040

The base PR is merged now, please sync with main.

geetu040 · Mar 24, 2026

@satvshr the tests are failing because the cache is not in the expected format, see the first point in #1619 (review) and how it's done in #1619
so you need meta.json and headers.json which you can simply copy from the other pr and rename task.xml to body.bin

geetu040

delete the old files in tests/files so git identifies and marks them as renamed files which would make it easier to track

a lot of irrelevant files are touched in tests, probably from your other pr's pre-commit, please revert them

see the comments on _get_estimation_procedure_list
don't remove this function, keep it as it is, it's updated here #1604 (changes)
call it separately in list_tasks and pass onwards to openml._backend.task.list as a parameter
it should stay out of _api/
keep test__get_estimation_procedure_list

remove TaskV1API and TaskV2API import in openml/tasks/functions.py

geetu040 · Mar 25, 2026

openml/_api/resources/base/resources.py

+        encoding: str = "utf-8",
+        file_name: str = "response.txt",
+        md5_checksum: str | None = None,
+    ) -> Path:


where is this used really, I cannot find?

The place it was being used was removed by another PR, removing this

geetu040 · Mar 25, 2026

openml/_api/resources/task.py

+        response = self._http.get(f"task/{task_id}", enable_cache=True)
+        return self._create_task_from_xml(response.text)
+
+    def _create_task_from_xml(self, xml: str) -> OpenMLTask:


this method doesn't use self, make this a static method, apply this for other private methods as well.

geetu040 · Mar 25, 2026

openml/_api/resources/task.py

+
+        return pd.DataFrame.from_dict(tasks, orient="index")
+
+    def _get_estimation_procedure_list(self) -> builtins.list[dict[str, Any]]:


this should stay out of _api/

geetu040 · Mar 25, 2026

openml/tasks/functions.py

though there are lot's of changes in this file but they are all clean, nicely done.

I see you are importing TaskV1API and TaskV2API, which is completely unacceptable and kills the purpose of migration. Please find a way to bypass this, move that functionality in the classes and access them through a common TaskAPI interface

geetu040 · Mar 25, 2026

openml/tasks/functions.py

-        raise OpenMLCacheException(f"Task file for tid {tid} not cached") from e
-
-
-def _get_estimation_procedure_list() -> list[dict[str, Any]]:


don't remove this function, keep it as it is, it's updated here #1604 (changes)
call it separately in list_tasks and pass onwards to openml._backend.task.list as a parameter

We will then have to alter the signature of openml._backend.task.list to accept _get_estimation_procedure_list as a permanent argument, which doesnt make sense?

I think that would make sense, why not?

geetu040 · Mar 25, 2026

tests/test_tasks/test_task_functions.py

+    @pytest.mark.skipif(
+        os.getenv("OPENML_USE_LOCAL_SERVICES") == "true",
+        reason="Pending resolution of #1657",
+    )


I don't think we should skip these

geetu040 · Mar 25, 2026

tests/test_tasks/test_task_functions.py

+        reason="Pending resolution of #1657",
+    )
    @pytest.mark.test_server()
    def test_download_split(self):


as suggested in #1619 (review)

geetu040 · Mar 25, 2026

tests/test_tasks/test_task_methods.py

nicely done, do the same for tests/test_tasks/test_task_functions.py

geetu040 · Mar 25, 2026

tests/test_tasks/test_task_methods.py


    @pytest.mark.test_server()
    def test_get_train_and_test_split_indices(self):
+        import unittest.mock


move import to the top

geetu040 · Mar 25, 2026

tests/conftest.py

would fail if you delete the old files in tests/files, you can keep it like the suggestion in #1619 (review)

geetu040

I've updated #1619 (review). Please sync with main and update cache files accordingly.

geetu040 · Mar 25, 2026

openml/tasks/task.py

+            Tag to attach to the task.
+        """
+        if self.task_id is None:
+            raise ValueError("Task does not have an ID. Please publish the task before tagging.")


use ObjectNotPublishedError as in _tag_openml_base

geetu040 · Mar 25, 2026

openml/tasks/task.py

+            raise ValueError(
+                "Dataset does not have an ID. Please publish the dataset before untagging."
+            )


same as above

geetu040 · Mar 26, 2026

openml/tasks/task.py

There is cache and api-calls which are needed to be updated in this file. I think you'd only need to update OpenMLTask.download_split. You should use _http.download here. Let me know if you need help.

geetu040 mentioned this pull request Jan 9, 2026

[ENH] V1 → V2 API Migration #1575

Open

18 tasks

satvshr marked this pull request as ready for review January 12, 2026 15:29

geetu040 suggested changes Jan 13, 2026

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examples/Advanced/fetch_evaluations_tutorial.py Show resolved Hide resolved

satvshr marked this pull request as draft January 14, 2026 20:25

satvshr changed the title ~~[ENH] Tasks Migration~~ [ENH] V1 → V2 API Migration - Tasks Jan 15, 2026

geetu040 suggested changes Jan 15, 2026

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geetu040 assigned satvshr Jan 19, 2026

geetu040 suggested changes Jan 20, 2026

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geetu040 suggested changes Jan 30, 2026

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geetu040 and others added 16 commits February 2, 2026 12:05

move enums

e2d059b

module level imports

d156ad4

module level import for _backend

d7a3788

module level import for tests

b5b9ef6

Merge branch 'main' into migration

68820fe

add test: test_tag_and_untag

567eca4

disabling parallel runs

06405c8

disabling windows CI

e22b7ca

implement get/set_config_values

b2287c3

improve APIBackend.set_config_values

b7e285e

use LegacyConfig

fd43c48

Revert "use LegacyConfig"

f4aab6b

This reverts commit fd43c48.

implement _sync_api_config

d43cf86

update tests with _sync_api_config

3e323ed

rename config: timeout -> timeout_seconds

9195fa6

use timedelta for default ttl value

5342eec

Merge branch 'main' into migration

8de99b7

geetu040 suggested changes Mar 13, 2026

View reviewed changes

geetu040 and others added 10 commits March 16, 2026 20:12

create enum ServerMode

7d61107

update config for ServerMode

1ecbbba

update tests for ServerMode

65472ed

Merge branch 'main' into tasks

b5eba2b

latest

f11ca75

udpate apikey in _TEST_SERVERS_LOCAL

44b48b5

bug fixing

73f609e

fix: remove duplicate server name in cache path

04bc83b

identified in https://github.com/openml/openml-python/actions/runs/23148612114/job/67243650521?pr=1609

test: remove check for ":" since windows CI expects it

f926092

identified in https://github.com/openml/openml-python/actions/runs/23430963986/job/68156944423?pr=1576

Merge remote-tracking branch 'geetu040/migration' into tasks

caed1d1

geetu040 reviewed Mar 23, 2026

View reviewed changes

This was referenced Mar 23, 2026

[ENH] V1 → V2 API Migration - datasets #1608

Open

[ENH] V1 -> V2 Migration : Runs #1616

Open

[ENH] V1 → V2 API Migration - setups #1619

Merged

geetu040 reviewed Mar 24, 2026

View reviewed changes

bug fixing

d488c3c

geetu040 suggested changes Mar 24, 2026

View reviewed changes

merge main

dc50f3d

satvshr added 3 commits March 24, 2026 17:39

bug fixing

d4b033e

bug fixing

cebf764

Trigger Build

ca8b72d

geetu040 suggested changes Mar 25, 2026

View reviewed changes

satvshr added 2 commits March 26, 2026 13:36

first round of changes

844faf5

first round of changes

9a752eb

geetu040 suggested changes Mar 26, 2026

View reviewed changes



		class OpenMLTask(OpenMLBase):
		class OpenMLTask(OpenMLBase, ResourceAPI):


		return pd.DataFrame.from_dict(tasks, orient="index")

		def _get_estimation_procedure_list(self) -> builtins.list[dict[str, Any]]:

		raise OpenMLCacheException(f"Task file for tid {tid} not cached") from e


		def _get_estimation_procedure_list() -> list[dict[str, Any]]:

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