docs: [FC-0074] add more detailed docs on filters

[mariajgrimaldi]

Description

This PR improves the concept section of the documentation by adding a new document dedicated only to Open edX Filters.

Initially, I also added two additional modifications:

1. Update references in the Hooks Extension Framework document and explain why the framework should be adopted.
2. Adding a new document comparing Open edX Events vs Filters to ease adoption.

Which I later dropped in favor of centralizing shared documentation docs.openedx.org and avoiding duplication across repos: So I'll be moving those docs to docs.openedx.org, Here's the PR for the implementation: openedx/docs.openedx.org#599

For more details on the decision, please see this thread.

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Thanks for the pull request, @mariajgrimaldi!

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[mariajgrimaldi]

@sarina @Apgomeznext: here's the WIP I've been working on for the 1.1 Improve Definitions and Update Outdated References in the Framework project feature.

I discussed with AnaP having feedback loops within the maintenance team about the documents' content. She'd get involved to review the document structure once she has the capacity for the project. So, early feedback is welcome.

[sarina]

@mariajgrimaldi thanks for sharing. I did a quick skim, it looks like it's off to a good start. Regarding duplicating documentation, I would strongly recommend against this. I would make a centralized document, and link to that as needed.

[mariajgrimaldi]

Thank you, @sarina. I agree we should solve this duplication of documents, so I moved some of these documents to a subsection of Concepts and Guides in the docs.openedx.org docs: openedx/edx-platform#35733. That PR references documents from each event and filters repos. My only concern is that leaving the docs there suggests the framework is edx-platform scoped when it's not. Would a single repo for the shared definitions of the framework be possible?

[sarina]

@mariajgrimaldi why not put the shared docs in https://github.com/openedx/docs.openedx.org ?

[mariajgrimaldi]

@sarina -- I thought about adding it here. It would have been something like OEP-50 Overview. We wouldn't have the misconception that the framework is edx-platform scoped, but it felt randomly placed.

So now that you mentioned it, I tried digging more into the docs sections and found this: https://docs.openedx.org/en/latest/developers/references/developer_guide/extending_platform/index.html. However, the extensions listed there are more content-focused, not like those listed here: https://docs.openedx.org/projects/edx-platform/en/latest/concepts/extension_points.html, where folder where I'm currently adding the documents. This is entirely out of this project's scope, but should we move those extension points to docs.openedx.org?

For the time being, I'll move the hooks docs from edx-platform to the Extending the Open edX Platform section.

[sarina]

@mariajgrimaldi the Developers Guide on the docs site isn't in Diataxis format, so I wouldn't add more to it. I think adding a Concept doc makes sense. You could link to the Concept doc in the Developer's Guide as well, but I think it'll be more visible/easier to find as a Concept guide.

[mariajgrimaldi]

@sarina: I'll be following your suggestions from openedx/openedx-events#406 here as well! Thank you :)

[sarina]

Looks good!

[sarina]

Suggested change

	#. The next function :math:`f_0` receives the potentially modified arguments and applies further operations, returning another modified set of arguments. This process continues through the list of functions.
	#. The next function (if there are more than one) :math:`f_1` receives the potentially modified arguments and applies further operations, returning another modified set of arguments. This process continues through the list of functions.

I think this is what you mean?

[mariajgrimaldi]

Yes! Thank you :)

370616d

[sarina]

Suggested change

	#. Each subsequent function :math:`f_{i+1}` receives the output from the previous function and returns its modified output until all functions have been executed.
	#. Each subsequent function :math:`f_{n+1}` receives the output from the previous function and returns its modified output until all functions have been executed.

[mariajgrimaldi]

I think using f_{i+1} it'd be even more confusing, so I removed it completely.

[sarina]

Suggested change

	#. The filter's tooling retrieves the configuration from ``OPEN_EDX_FILTERS_CONFIG``, which defines a list of N functions :math:`f_0, f_1, \ldots, f_{n-1}` that will be executed.
	#. The filter's tooling retrieves the configuration from ``OPEN_EDX_FILTERS_CONFIG``, which defines a list of N functions :math:`f_0, f_1, \ldots, f_{n}` that will be executed.

I think I might just use n because n-1 I would assume there's a final n step

[mariajgrimaldi]

Oh, good suggestion. So we'll start counting from 1 instead, then, if that's more straightforward.

[sarina]

Suggested change

Developers can implement functions in an `Open edX Django plugin`_, configure them for a particular filter in the ``OPEN_EDX_FILTERS_CONFIG`` setting, modifying the application flow when a the filter in question is invoked by the process in execution. These functions can the application's behavior by altering data, adding new data, or stopping execution by raising exceptions. For example, a filter can stop a student's enrollment if certain conditions, such as business rules, are not met.

Developers can implement functions in an `Open edX Django plugin`_, configure them for a particular filter in the ``OPEN_EDX_FILTERS_CONFIG`` setting, and modify the application flow when a the filter in question is invoked by the process in execution. These functions can the application's behavior by altering data, adding new data, or stopping execution by raising exceptions. For example, a filter can stop a student's enrollment if certain conditions, such as business rules, are not met.

[mariajgrimaldi]

Thanks!

[mariajgrimaldi]

Hey, @openedx/hooks-extension-framework, can some of you help me review this PR from a technical perspective so we can ensure we didn't miss anything?

Thank you!

[Ian2012]

LGTM