fix: make page a nullable property and specs updated

[marslanabdulrauf]

What are the relevant tickets?

https://github.com/mitodl/hq/issues/10652

Description (What does it do?)

This pull request updates the course and program serializers to properly handle cases where a course or program does not have an associated CMS page. The serializers now return null for the page field instead of a default object, and the OpenAPI specs are updated to reflect this. Corresponding tests are added to ensure this behavior.

Serializer improvements:

• Updated CourseSerializer and ProgramSerializer to allow the page field to be null if there is no associated CMS page, returning None instead of a default object. (courses/serializers/v2/courses.py [1] courses/serializers/v2/programs.py [2]
• Cleaned up imports in programs.py by removing unused get_thumbnail_url. (courses/serializers/v2/programs.py courses/serializers/v2/programs.pyL15-R15)

OpenAPI specification updates:

• Added nullable: true to the page fields for courses and programs in all OpenAPI spec versions (v0.yaml, v1.yaml, v2.yaml) to indicate that these fields can be null.

Testing:

• Added tests to verify that the serializers return page: None when a course or program does not have a CMS page. (courses/serializers/v2/courses_test.py [1] courses/serializers/v2/programs_test.py [2]

How can this be tested?

[github-actions]

OpenAPI Changes

Show/hide ## Changes for v0.yaml:

## Changes for v0.yaml:
No changes detected

## Changes for v1.yaml:
No changes detected

## Changes for v2.yaml:
19 changes: 19 error, 0 warning, 0 info
error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/course_certificates/{cert_uuid}/
		the response property `course_run/course/allOf[#/components/schemas/V2Course]/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/courses/
		the response property `results/items/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/courses/{id}/
		the response property `page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/enrollments/
		the response property `items/run/allOf[#/components/schemas/V2CourseRunWithCourse]/course/allOf[#/components/schemas/V2Course]/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API POST /api/v2/enrollments/
		the response property `run/allOf[#/components/schemas/V2CourseRunWithCourse]/course/allOf[#/components/schemas/V2Course]/page` became nullable for the status `201`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/pages/?fields=*&type=cms.coursepage
		the response property `items/items/course_details/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/pages/?fields=*&type=cms.programpage
		the response property `items/items/program_details/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/pages/{id}/
		the response property `oneOf[#/components/schemas/CoursePageItem]/course_details/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/pages/{id}/
		the response property `oneOf[#/components/schemas/ProgramPageItem]/program_details/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/program_certificates/{cert_uuid}/
		the response property `program/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/program_enrollments/
		the response property `items/enrollments/items/run/allOf[#/components/schemas/V2CourseRunWithCourse]/course/allOf[#/components/schemas/V2Course]/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/program_enrollments/
		the response property `items/program/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API DELETE /api/v2/program_enrollments/{id}/
		the response property `items/enrollments/items/run/allOf[#/components/schemas/V2CourseRunWithCourse]/course/allOf[#/components/schemas/V2Course]/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API DELETE /api/v2/program_enrollments/{id}/
		the response property `items/program/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/program_enrollments/{id}/
		the response property `enrollments/items/run/allOf[#/components/schemas/V2CourseRunWithCourse]/course/allOf[#/components/schemas/V2Course]/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/program_enrollments/{id}/
		the response property `program/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/programs/
		the response property `results/items/page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API GET /api/v2/programs/{id}/
		the response property `page` became nullable for the status `200`

error	[response-property-became-nullable] at head/openapi/specs/v2.yaml	
	in API POST /api/v2/verified_program_enrollments/{courserun_id}/
		the response property `run/allOf[#/components/schemas/V2CourseRunWithCourse]/course/allOf[#/components/schemas/V2Course]/page` became nullable for the status `201`

Unexpected changes? Ensure your branch is up-to-date with main (consider rebasing).

[marslanabdulrauf]

@ChristopherChudzicki should we bump the version for breaking change which is causing github check failure ?

[ChristopherChudzicki]

@ChristopherChudzicki should we bump the version for breaking change which is causing github check failure ?

Sorry I didn't have time to review this more carefully today, but IMO this isn't a breaking change—it's just making the spec accurate. The API can return null now, but the spec doesn't reflect that. We aren't changing the API, we are fixing the spec.

[marslanabdulrauf]

Oh, I checked the V2Course serializer didn't had allow_null=True which I added and generated the v2 specs.

Also had similar requirement for Programs as well:

Additionally, api/v2/programs page has an incorrect type in the spec. Sometimes it's the full page object, sometimes it's just { feature_image_src }. My preference would be to make a breaking change to the api/v2/programs api to make it nullable, rather than the { feature_image_src } fallback which is never used on MITxOnline or Learn. (The fallback for v1 is used, I believe.)

So made changes around that as well and updated the v2 specs.

[ChristopherChudzicki]

Oh, I checked the V2Course serializer didn't had allow_null=True which I added and generated the v2 specs.

👍 That sounds good to me. Again, not a breaking change—the serializer already returned null for page, e.g., https://mitxonline.mit.edu/api/v2/courses/course-v1:UAI_NTUA_SOURCE+NTUA.UAI.VT.3/ (since DRF serializers don't validate responses, only requests).

My suggestion is:

1. Fix tests / linting (the linting failure is probably pre-existing, but the line number changed, so it's not getting excluded by drf_lint_baseline.json anymore...may need to regenerate that.)
2. Before we merge, let's get a PR ready for MIT Learn for the updated client. The change to nullable page is accurate—reflects reality—but will trigger some new TS warnings in MIT Learn. We can generate a API client for the branch via https://github.com/mitodl/mitxonline-api-clients#branch-clients-local-development and prepare the Learn PR