wpseek.com
A WordPress-centric search engine for devs and theme authors

function wp_get_random_content_post_types( WP_Query $query ): array {
	$post_types = $query->get( 'post_type' );

	if ( empty( $post_types ) && $query->is_tax() && $query->tax_query instanceof WP_Tax_Query ) {
		// Match WP_Query::get_posts(): searchable post types using any of the queried taxonomies.
		$taxonomies = array_keys( $query->tax_query->queried_terms );
		$post_types = array();

		foreach ( get_post_types( array( 'exclude_from_search' => false ) ) as $post_type ) {
			$object_taxonomies = 'attachment' === $post_type ? get_taxonomies_for_attachments() : get_object_taxonomies( $post_type );
			if ( array_intersect( $taxonomies, $object_taxonomies ) ) {
				$post_types[] = $post_type;
			}
		}
	} elseif ( empty( $post_types ) && ! $query->is_search() ) {
		$post_types = array( 'post' );
	}

	if ( empty( $post_types ) || 'any' === $post_types ) {
		$post_types = get_post_types( array( 'exclude_from_search' => false ) );
	}

	$random_post_types = array();

	foreach ( (array) $post_types as $post_type ) {
		// Plugins may set invalid values on the `post_type` query variable.
		if ( ! is_string( $post_type ) ) {
			continue;
		}

		$post_type_object = get_post_type_object( $post_type );

		if ( $post_type_object && $post_type_object->randomable ) {
			$random_post_types[] = $post_type_object->name;
		}
	}

	return $random_post_types;
}