Search in custom post type AND in pages with category

Question

I have a search field that's searching in my custom post type bwps with a hidden input:

<form class="search-form form-inline" action="<?php echo site_url('/'); ?>" method="get" role="search">
  <label class="sr-only"></label>
  <input class="searchInput" type="search" required="" placeholder="<?php _e('Search for event', 'mhe') ?>" name="s" value=""></input>
  <input type="hidden" name="post_type" value="bwps" />
  <button class="searchButton" type="submit"><span class="glyphicon glyphicon-search" aria-hidden="true"></span> <span class="searchButtonText"><?php _e('Search', 'mhe') ?></span></button>
</form>

However, the customer now also wants that it searches within all pages, but only pages with a specific category.

How can I make this search form search EVERYTHING in the custom post type, but also ONLY pages with a specific category? Is this even possible?

Answer 1

You may have already solved this months ago, but I here's my 2 cents as I thought this was an interesting question.

I don't think the standard WP search query can be used to search for posts with either (post type A) or (post type B and category C). But you could pass a custom where clause to the query with posts_where filter to handle this kind of case.

I think something like this should work,

add_filter( 'posts_where' , 'my_posts_where', 10, 2 );
function my_posts_where( $where, $query ) {

    if ( is_admin() || ! is_search() || ! is_main_query() ) {
        return $where;
    }

    // check that requred $_GET parameters are set
    if ( ! empty( $_GET['post_type'] ) || 'bwps' !== $_GET['post_type'] ) {
        return $where;
    }

    if ( empty( $_GET['s'] ) ) {
        return $where;
    }

    // return custom where clause
    global $wpdb;
    $sql = "
        AND (
            {$wpdb->posts}.post_title LIKE '%%%s%%' OR
            {$wpdb->posts}.post_name LIKE '%%%s%%'
        )
        AND
            {$wpdb->posts}.post_status = 'publish'
        AND
            (
                (
                    {$wpdb->posts}.post_type = 'bwps'
                ) OR
                (
                    {$wpdb->posts}.post_type = 'page'
                    AND
                    {$wpdb->posts}.ID IN (
                        SELECT {$wpdb->posts}.ID FROM {$wpdb->posts} AS p
                        INNER JOIN {$wpdb->term_relationships} AS tr ON (p.ID = tr.object_id)
                        INNER JOIN {$wpdb->term_taxonomy} AS tt ON (tr.term_taxonomy_id = tt.term_taxonomy_id)
                        INNER JOIN {$wpdb->terms} AS t ON (t.term_id = tt.term_id)
                        WHERE
                            p.post_status = 'publish'
                            AND t.term_id = %d
                            AND tt.taxonomy = 'category'
                    )
                )
            )
    ";

    $search_phrase = '%' . $_GET['s'] . '%';
    $term_id = 1;

    return $wpdb->prepare(
        $sql,
        $search_phrase,
        $search_phrase,
        $term_id
    );
}