Ability to disable hyphen-based exclusion in searches

[chriseverson]

In 4.4.0, the ability to prepend a search term with hyphen to indicate exclusion was added to the codebase.

This behavior is awesome 99.9% of the time, however I recently found myself working on site where this behavior is problematic due to the fact that their products are named, quite often, using hyphens, in the same fashion.

​https://sunrisescience.com/?s=PABA&post_type=product is an example of this need in action. Searching PABA returns all products with "PABA" in the title, however, the project requirements in this case require the ability to search for "-PABA" in the title and not "PABA" without the preceding hyphen.

I'd propose a new filter to toggle this functionality on and off, and will send a patch for that as soon as I find some time over the next day or two.

[boonebgorges]

Hi @chriseverson - Thanks for the ticket!

A filter for this seems like a good idea.

[chriseverson]

Patch for this issue using a new filter "wp_search_exclusion" with a default of true

[chriseverson]

For testing: In the above patch, it expects the following to disable the hyphen being a search operator:

add_filter( 'wp_search_exclusion', '__return_false' );

I'm not entirely in love with the naming of the filter, so if anyone has any better ideas, I can update accordingly.

[boonebgorges]

Patch looks good, @chriseverson!

How about something more verbose for the filter name? Maybe wp_query_use_hyphen_for_negation?

If you're able to write a test that demonstrates that the filter works, it'd help to expedite this ticket. The existing tests are here https://core.trac.wordpress.org/browser/tags/4.6.1/tests/phpunit/tests/query/search.php#L62

[chriseverson]

Updated patch filter name to "wp_query_use_hyphen_for_negation". Unit tests coming soon.

[choongsavvii]

Greetings from WordCamp NL contributor day!

38099.3.patch contains @chriseverson 's original patch, to which I added unit tests. Also updated the doc comment for the $s parameter, to make it easier to find this new filter.

[choongsavvii]

Apologies - one little update. Something didn't feel right. The filter was named _negation, but the variable and comments were all talking about _exclusion. I think the correct naming should be wp_query_use_hyphen_for_exclusion . The word 'negation' is used in a boolean context, but that is not the case here - we are actually excluding stuff.

38099.4.patch reflects this renaming.

[chriseverson]

I agree, "exclusion" seems much more semantically appropriate than "negation".

[boonebgorges]

I'll review this.

[choongsavvii]

One more adjustment, as suggested by @jorbin in Slack:

`__return_true` is for calbacks with things like `add_filter`. You don't pass a callback to `apply_filters`, you pass the value you want to filter. In this case we want to filter the bool

Changed in 38099.5.patch - thanks @jorbin !

[boonebgorges]

In 38792:

Query: Allow the hyphen-prefix-for-search-exclusion feature to be disabled by filter.

WordPress 4.4 introduced "hyphen exclusion" for search terms, so that
"foo -bar" would return posts containing "foo" AND not containing "bar".
The new filter 'wp_query_use_hyphen_for_exclusion' allows developers
to disable this feature when it's known that their content will contain
semantically important leading hyphens.

Props chriseverson, choongsavvii.
Fixes #38099.

[dlh]

I apologize for reopening this ticket after the earlier work on it and so late in this cycle's enhancement window.

It seems to me like core could allow a developer working with content containing semantically important hyphens to still support search exclusions by letting them change the "exclusion prefix" to something other than a hyphen.

Would folks be amenable to a patch that allowed the prefix to be filtered, rather than a filter that toggles the whole feature? If so, I'm happy to help try to write it. The filter could also support "return false to disable" for developers who need it.

Or, let me know if I'm misunderstanding something.

[boonebgorges]

@dlh Sure, I'd be glad to see a patch that does that. The sooner the better :)

[dlh]

Thanks, @boonebgorges. My attempt is attached as 38099.6.patch​.

[boonebgorges]

Thank you, @dlh! This looks like an improvement. I'm going to make a few changes for readability and go with it.

[boonebgorges]

In 38844:

Query: Allow the prefix used for search term exclusion to be filtered.

[38792] allowed WP_Query's hyphen-as-exclusion-prefix feature to be
disabled via filter. A more general solution is to allow the prefix to
be filtered; returning an empty value from a filter callback works to
disable the feature.

Props dlh.
Fixes #38099.