Terms Query inspector controls revamp + add subterms option

[kmanijak]

What?

Closes

1. Split Terms Query Inspector Controls into separate, more manageable files
2. Introduce new attribute termToShow for high-level, predefined set of "filters"
3. Restructure the options so they're less entangles and dependant on each other into more hierarchical approach
4. Add "Subterms only" option automatically displaying subterms of currently viewed taxonomy archive

Why?

Subterms option is highly demanded. It should be easy to include Terms Query into taxonomy template and have it automatically display subterms of currently viewed taxonomy term.

This dictated restructure so there's no conflict between "Show only top level" vs "Show hierarchial", etc.

How?

New Inspector Controls logic is as follows with "Terms to Show" being radio button so options are mutually exclusive which removes the confusion where we had options conflicting with each other:

Examples:

Case	Example	Inspector Controls
Non-hierarchical taxonomy	Tags on Category archive
Hierarchical taxonomy on page - "All terms"	Category on page
Hierarchical taxonomy on page - other option	Category on page - show hierarchy not displayed
Hierarchical taxonomy on its archive - "All terms"	Category on Category Archives
Hierarchical taxonomy on its archive - other option	Category on Category Archives - show hierarchy not displayed

And it works fine with custom taxonomies like Product Categories from WooCommerce, showing subcategories in Products by Category page:

Categories hierarchy	Editor	Frontend
See Books & Toys direct children

Testing Instructions

0. Ensure experimental blocks are enabled.

Not taxonomy archive template

1. Insert Terms Query in post
2. Choose Tags as taxonomy
3. Expected: There's only "All terms" option available
4. Choose Category as taxonomy
5. Expected:
   • There's "All terms" and "Show top level only" options available
   • "All terms" chosen as default
   • "Show hierarchy" is available
6. Change to "Show top level only"
7. Expected: Change is reflected in query and "Show hierarchy" disappeared

Taxonomy archive template

1. Go to Category Archives template
2. Insert Terms Query
3. Expected:
   • There's "All terms", "Show top level only" and "Show subterms only" options available
   • "All terms" chosen as default
   • "Show hierarchy" is available
4. Change to "Show subterms only"
5. Expected: Change is reflected in query (we cannot determine in editor what to show exactly so I decided to display any subterms - the opposite of top level) and "Show hierarchy" disappeared
6. Save and go to category page on the frontend
7. Expected: Only subcategories of category you visit are displayed

Other

1. Play around and change the setting to see if they default to correct values etc.

Testing Instructions for Keyboard

Screenshots or screencast

Before	After

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Co-authored-by: kmanijak <karolmanijak@git.wordpress.org>
Co-authored-by: mikachan <mikachan@git.wordpress.org>
Co-authored-by: Marc-pi <mdxfr@git.wordpress.org>

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[Marc-pi]

@kmanijak awesome :-) that's the exact need. kudos

[mikachan]

I've left some minor comments, but otherwise this is looking good. Thanks so much for working on it, it's a great refactor!

I'll give this another test once it's been rebased after #71656 being merged.

[kmanijak]

Thanks for initial review @mikachan! Conflict has been resolved and also I addressed your comments, it's ready for another round of review! 🙌

[mikachan]

This is testing as expected following the testing instructions 🎉

• Non-taxonomy archive template ✅
• Taxonomy archive template ✅
• Played around and changed the settings to see if they default to correct values ✅

I've left one more inline comment, but otherwise I think this is good to bring in ✨

[mikachan]

I've noticed a potential bug when using the "Show hierarchy" option in a post. It looks like the subterms are duplicated below the main query on the front end, but they display as expected in the editor:

Editor	Front end

[kmanijak]

I've noticed a potential bug when using the "Show hierarchy" option in a post. It looks like the subterms are duplicated below the main query on the front end, but they display as expected in the editor:

@mikachan, thank you for spotting it! Eventually it's a oneliner fix but took me a moment to spot a problem 😅 734b35a. I didn't set parent properly, as I didn't realise the children terms are fetched separately in render_block_core_term_template_get_children. I think we could optimise it and avoid additional queries and just build the structure ourselves after one query. But I don't think it's immediate need.

[mikachan]

Looks like that fixes it!

I think we could optimise it and avoid additional queries and just build the structure ourselves after one query. But I don't think it's immediate need.

Yep, sounds like a good follow-up.