Add "Archives" block

[swissspidy]

This is a possible implementation for an archives block that uses the same code as the archives widget currently in code. The same code and filters are used for output on the front end, so there shouldn't be any BC concerns.

Todo:

• Add server-side rendering, either through a custom REST API endpoint or something like Server side rendering API endpoint #780.
  Right now, a fake loading screen is shown in the editor.
• Testing
• Styling
• Accessibility improvements
  Probably something to happen in core directly, see Add Block: Archive #1464 (comment)). Not really a blocker for this implementation
• Maybe implement alignment options

Screenshots:

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Fixes #1464.

[westonruter]

For alignment options, see #1803.

[westonruter]

This needs to be changed in light of #2014.

[aduth]

Note with #2172, these need to be updated to prefix the dependencies with @wordpress/. You will need to perform a rebase against the latest version of master and apply your changes:

git fetch origin
git rebase origin/master

[gziolo]

@swissspidy, do you plan to continue the work started in this PR. It might require some extra work to make it up to date.

[swissspidy]

@gziolo Seeing that #1464 was miraculously reopened, sure :) Some guidance would be nice re: the REST API question at the beginning. Is there any precedence for this nowadays?

[gziolo]

Not sure what the issue was, but you can see how it was done for the Latest Posts block. See https://github.com/WordPress/gutenberg/tree/master/blocks/library/latest-posts.

[westonruter]

@swissspidy I don't think that we should use the REST API to populate the editor preview. We could instead use the ServerSideRender as proposed in #780 which would eliminate the need to duplicate the PHP rendering logic in JS.

[westonruter]

Per @mtias in Slack:

It doesn’t exclude having a server side render component for other widgets (maybe calendar, tag cloud, etc), but I don’t believe we should be blocked by the lack of such endpoint/component, and we should definitely start already with blocks like “archives”.

So this should move forward now without ServerSideRenderer to be like the Latest Posts block. A new endpoint in the gutenberg namespace will probably be needed to obtain the data required for rendering an Archives block.

[miina]

@swissspidy since the ticket can move forward without ServerSideRenderer are you planning to continue work on it? :) Asking since if you wouldn't, I'd be interested in giving it a try and picking up where you left off.

[swissspidy]

@miina Go for it! :) Feel free to pick some bits of this PR and let me know if I can help with anything.

[westonruter]

Closing in favor of #1518 where this work is being picked up.

[afercia]

For reference: I guess it's #5495