Add filter to make extending searching easier

[mark8barnes]

I'm using custom post types, and want to extend the search function so more than post_title and post_content are searched. It is currently possible to filter posts_search but that returns a string such as AND (((wp_posts.post_title LIKE '%test%') OR (wp_posts.post_content LIKE '%test%'))) . This string then has to be rather messily manipulated via preg_replace or str_replace.

It would be more useful if we could filter a list of fields to be added to the search criteria, so that we could add a function to extend or change the criteria:

add_filter ('search_fields', 'my_custom_search_fields');

function my_custom_search_fields ($fields) {
    global $wpdb;
    $fields[] = "{$wpdb->prefix}posts.post_excerpt";
    return $fields;
}

The attached patch implements that filter.

Patch to filter search fields

+1 on this. Sort of related: #7394

This line is incorrect though:

$search_fields = array( $wpdb->posts.post_title, $wpdb->posts.post_content );

It should be:

$search_fields = array( "$wpdb->posts.post_title", "$wpdb->posts.post_content" );

Also, I'm wondering if it should be a bit more highlevel, i.e. without the $wpdb->posts prefixing.

Right, no need for the prefix there. Also a bit unsure of the user case for this: what other fields apart from the excerpt are searchable with LIKE? If it's only for post_excerpt perhaps it can be pre-set/limited to only title, content and excerpt. Then the filtered array can probably be:

$search_fields = array(
  'post_title' => true,
  'post_content' => true,
  'post_excerpt' => false
);

what other fields apart from the excerpt are searchable with LIKE?

If you handle the JOINs, you can search through several custom fields or even term names, so maybe keeping the prefix is better.

Replying to scribu:

what other fields apart from the excerpt are searchable with LIKE?

If you handle the JOINs, you can search through several custom fields or even term names, so maybe keeping the prefix is better.

Maximum flexibility is definitely needed. With the patch you can search custom meta data, terms or data stored in other custom post types (by joining tables with the posts_join_paged filter), or even do more complicated lookups (by using the posts_fields filter and nesting a SELECT).

One obvious real-world scenario that the filter would make possible (together with a JOIN) would be being able to extend the search at wp-admin/edit.php to include tags.

Revised patch incorporating scribu's correction

This missed the deadline for hard feature freeze by a week (when it was moved to 3.5), and still no review, testing, or unit tests. Punting.