Taxonomy: Allow searching terms containing ampersands and HTML entities

[robelsust]

Taxonomy: Allow searching terms containing ampersands and HTML entities

Trac ticket: https://core.trac.wordpress.org/ticket/66279

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Description

When term names are saved in WordPress, _wp_specialchars() encodes ampersands as & into wp_terms.name (priority 30 on pre_term_name in default-filters.php).

Prior to this change, WP_Term_Query::get_search_sql() created search clauses using only the raw $search value:

((t.name LIKE '%search%') OR (t.slug LIKE '%search%'))

Because MySQL does not equate raw '&' with '&', searching for terms containing ampersands (such as "Tour & ", "Tour & Travel", or "& Travel") failed completely on both wp-admin/edit-tags.php and any queries powered by WP_Term_Query / get_terms( array( 'search' => ... ) ).

Solution

In WP_Term_Query::get_search_sql():

1. Check if the search term contains characters requiring HTML entity encoding (_wp_specialchars( $search, ENT_COMPAT, 'UTF-8', true )).
2. Decode pre-encoded entities (wp_specialchars_decode()) to support searches submitted with entities.
3. If distinct variants are found, expand the search query with an OR condition across both forms:

   (((t.name LIKE '%Tour & %') OR (t.slug LIKE '%Tour & %')) OR ((t.name LIKE '%Tour & %') OR (t.slug LIKE '%Tour & %')))

4. If no special characters are detected, a single clause is generated, preserving identical execution and indexing performance for standard terms.

Testing Instructions

1. Create a category named Tour & Travel.
2. Search for Tour & (with a trailing space) on Posts -> Categories (wp-admin/edit-tags.php?taxonomy=category).
3. Verify that Tour & Travel is found in the search results table.
4. Run PHPUnit test suite:

   vendor/bin/phpunit tests/phpunit/tests/term/getSearchSql.php
   vendor/bin/phpunit -c tests/phpunit/multisite.xml tests/phpunit/tests/term/getSearchSql.php

5. Run PHPCS:

   vendor/bin/phpcs src/wp-includes/class-wp-term-query.php tests/phpunit/tests/term/getSearchSql.php

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[SainathPoojary]

Thanks for working on this. This fixes server-side searches containing a raw ampersand.

I also checked the reported issue in the block editor. Searching for "Tour & " still hides the category with this PR applied.

The reported block editor issue still occurs because Gutenberg filters category names in JavaScript. That part needs a separate fix in the Gutenberg.

[SainathPoojary]

There is one remaining case with encoded searches. Both Tour & Travel and Tour & Travel return no results for the existing category. Decoding produces Tour & Travel, but the stored name is Tour & Travel. Including the encoded form of the decoded value, with tests for these inputs, would cover this case.