[BB-9570] Implement Learning Path Enrollment API

[tecoholic]

Description

This PR implements the changes proposed in ADR 003.

List of changes introduced

• LearningPathEnrollment Model updates
• LearningPathEnrollmentAllowed Model
• Enroll API
• Fetch Enrollments API
• Bulk enrollment API

Testing instructions

Setting up the plugin in a turor env

1. Setup a tutor dev environment
2. Clone and checkout the PR branch
3. Add the repo as a tutor mount to the LMS container

tutor mounts add lms:/path/to/learning-paths-plugin:/mnt/learning-paths-plugin
tutor config save
tutor dev start -d

4. Install the plugin inside the LMS container and run the migrations

tutor dev dc exec lms bash
pip install -e /mnt/learning-paths-plugin
./manage.py lms migrate

Testing the API

1. Go to the LMS Admin > Learning_paths > Learning Path and create an object and copy it's UUID. This will be needed for testing the rest of the API.
2. Follow the Open edX REST Api guide and test the API endpoints.

[tecoholic]

@Agrendalath Hi, the CI fails due to missing PII annotation for the "HistoricalRecords" of the LearningPathEnrollment model. I couldn't find any references on how to handle this. Do you happen to know what's the right way to do here?

[Agrendalath]

Missing operations:

    operations = [
        migrations.AlterModelOptions(
            name="historicallearningpathenrollment",
            options={
                "get_latest_by": "history_date",
                "ordering": ("-history_date", "-history_id"),
                "verbose_name": "historical learning path enrollment",
            },
        ),
        migrations.AlterField(
            model_name="historicallearningpathenrollment",
            name="enrolled_at",
            field=models.DateTimeField(
                default=datetime.datetime(
                    2025, 3, 16, 12, 5, 48, 376085, tzinfo=datetime.timezone.utc
                ),
                help_text="Timestamp of enrollment or un-enrollment. To be explicitly set when performing a learner enrollment.",
            ),
        ),
        migrations.AlterField(
            model_name="learningpathenrollment",
            name="enrolled_at",
            field=models.DateTimeField(
                default=datetime.datetime(
                    2025, 3, 16, 12, 5, 48, 376085, tzinfo=datetime.timezone.utc
                ),
                help_text="Timestamp of enrollment or un-enrollment. To be explicitly set when performing a learner enrollment.",
            ),
        ),
    ]

Please squash them into 0006.

[tecoholic]

This is strange. I think this might be due to the difference in the versions of "django-simple-history" between our environments. My redwood environment has been broken and the openedx-dev image keeps failing to build. So, I used the sumac branch for testing.

I will try to get the redwood up again and regenerate the migrations.

[Agrendalath]

@tecoholic, you don't need to use Redwood for this. I see that all Open edX requirements from Redwood to the latest version specify django-simple-history==3.4.0, while the common constraints contain the following:

# django-simple-history>3.0.0 adds indexing and causes a lot of migrations to be affected
django-simple-history==3.0.0

It might be worth taking a look at the context of this constraint, as we typically don't want to have a version mismatch between the CI and instance.

[Agrendalath]

This pattern is repeated in a few places. Why don't we create the has_permission method that will return username if it exists and the request.user is staff or superuser. Otherwise, return request.user.username.

Also, please check if it doesn't raise 500 for AnonymousUser.

[tecoholic]

@Agrendalath This comment threw me off course for a while, before I realized that has_permission can return only True/False. This was a great suggestion nonetheless.

After a couple of attempts, I think I finally got a decent one implemented. I had also overdone the admin checks by checking for both is_staff and is_superuser in all the places. I was able to simplify that as well.

[Agrendalath]

As you have noted in the ticket, we should update all URLs to be prefixed with learning-paths for consistency.

[tecoholic]

Update the URLs and verified that they conform to existing conventions as well.

[Agrendalath]

Nit: why don't we use update_or_create for all of this?

[tecoholic]

@Agrendalath Good question. There is an edge case. When there is an active enrollment for the learning update_or_create will change the "enrolled_at" date of the enrollment. I couldn't find a way to set is_active for inactive enrollments, but not change enrolled_at for active enrollments.

[Agrendalath]

Nit: won't creating LearningPathEnrollmentAllowed automatically raise the exception? The EmailField already specifies this validator.

[tecoholic]

I checked and even have an unit-test to verify this. Unfortunately, invalid emails don't seem to raise an error.