Xblock version 5.0.0 broke plugin

[BrandonHBodine]

We have a plugin that is replacing the default XBlock with our own implementation that was recently broken with what we believe was the removal of pkg_resources support here #716.

We followed this post as our way of implementation https://discuss.openedx.org/t/override-default-edx-platform-xblock-mappings-without-forking/12441

Suspected root of the issue in our plugin:

    def ready(self):
        """
        Django startup code: swap edx-platform mapping for blocks with our translated versions.

        See https://discuss.openedx.org/t/override-default-edx-platform-xblock-mappings-without-forking/12441
        """

        # List of translated block types, for dismbiguating entry points
        translated_blocks = ["html", "problem", "video"]

        for block_type in translated_blocks:
            block_entry_points = list(
                pkg_resources.iter_entry_points("xblock.v1", block_type)
            )

            # If we have multiple entry points, ours gets precedence over the Open-edX copy
            if len(block_entry_points) > 1:
                dist = pkg_resources.get_distribution("Open-edX")
                del dist.get_entry_map("xblock.v1")[block_type]

[kdmccormick]

Thanks for the report. The root issue you've found looks correct to me. We've switched XBlock over from pkg_resources to importlib.metadata, and it seems that hack which worked before on pkg_resources does not apply over in importlib.metadata land.

On one hand, pkg_resources is not part of the public XBlock API, so I do not consider this to be a bug in XBlock. On the other hand, it seems valuable for operators to be able to customize XBlocks without forking edx-platform, so I do want to make sure there's a "supported workaround" for that.

I will spend some time this week thinking if there is a supported API we could add to XBlock for customizing blocks. In the meantime, @BrandonHBodine , let me know if you find a new workaround that works with XBlock==5.0.0.

[kdmccormick]

I've posted an idea in https://discuss.openedx.org/t/override-default-edx-platform-xblock-mappings-without-forking/12441/4

[nsprenkle]

I've posted an idea in https://discuss.openedx.org/t/override-default-edx-platform-xblock-mappings-without-forking/12441/4

Following up with this, I like the idea of having an XBlock-supported way to override a block as suggested by @kdmccormick. Happy to help design / review as we are under time pressure to get a change out.

[pomegranited]

Excellent fix for this issue @nsprenkle and @kdmccormick, thank you!

Do you know if anyone is working on removing the XBlock constraint from edx-platform? I don't want to upgrade to XBlock==5.1.0 in completion until we're using it in the platform.

Sorry for the noise! Found your openedx/edx-platform#35325.