WordPress ＋ Algoliaで、Algoliaの検索対象から特定の投稿（固定ページ）を除外するプラグイン

exclude-algolia-search.php

<?php
/*
Plugin Name: Exclude Algolia search
Plugin URI:
Description: Algolia の検索結果から除外するフラグを追加。WP Search with Algolia プラグインが必要。
Version: 0.1
Author: gatespace
Author URI: https://gatespace.jp
License: GPLv2 or later
*/

//Register Meta box

function exclude_algolia_search_meta_boxes() {
	$args = array(
		'public'   => true,
	);
	$my_screens = get_post_types( $args );
	foreach ( $my_screens as $screen ) {
		add_meta_box( 'exclude_algolia_search', 'Exclude Algolia search', 'exclude_algolia_search_cb', $screen, 'side' );
	}

}
add_action( 'add_meta_boxes', 'exclude_algolia_search_meta_boxes', 10, 1 );

//Meta callback function
function exclude_algolia_search_cb( $post ) {
	// Add an nonce field so we can check for it later.
	wp_nonce_field( 'exclude_algolia_search_box', 'exclude_algolia_search_box_nonce' );

	// Use get_post_meta to retrieve an existing value from the database.
	$value = get_post_meta( $post->ID, 'exclude_algolia_search_flag', true );

	// Display the form, using the current value.
	?>
	<p><label><input type="checkbox" name="exclude_algolia_search_flag" value="1" <?php checked( $value, 1 ); ?> >
	Exclude Algolia search</label></p>
	<?php
}

//save meta value with save post hook
function exclude_algolia_save_post( $post_id ) {
	/*
	 * We need to verify this came from the our screen and with proper authorization,
	 * because save_post can be triggered at other times.
	 */
	// Check if our nonce is set.
	if ( ! isset( $_POST['exclude_algolia_search_box_nonce'] ) ) {
		return $post_id;
	}

	// Verify that the nonce is valid.
	$nonce = $_POST['exclude_algolia_search_box_nonce'];
	if ( ! wp_verify_nonce( $nonce, 'exclude_algolia_search_box' ) ) {
		return $post_id;
	}

	/*
	 * If this is an autosave, our form has not been submitted,
	 * so we don't want to do anything.
	 */
	if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
		return $post_id;
	}

	// Check the user's permissions.
	if ( 'page' == $_POST['post_type'] ) {
		if ( ! current_user_can( 'edit_page', $post_id ) ) {
			return $post_id;
		}
	} else {
		if ( ! current_user_can( 'edit_post', $post_id ) ) {
			return $post_id;
		}
	}

	/* OK, it's safe for us to save the data now. */

	$value = isset($_POST['exclude_algolia_search_flag']) ? $_POST['exclude_algolia_search_flag'] : '';

	if ( ! empty( $value ) ) {
		update_post_meta( $post_id, 'exclude_algolia_search_flag', $value );
	} else {
		delete_post_meta( $post_id, 'exclude_algolia_search_flag' );
	}
}
add_action( 'save_post', 'exclude_algolia_save_post', 10, 1 );

// Hook into Algolia to manipulate the post that should be indexed.
function exclude_algolia_filter_post( $should_index, WP_Post $post ) {
	if ( false === $should_index ) {
		return false;
	}

	$exclude_algolia_search_flag = get_post_meta( $post->ID, 'exclude_algolia_search_flag', true );
	if ( 1 == $exclude_algolia_search_flag ) {
		return false;
	}

	return $should_index;
}
// Hook into Algolia to manipulate the post that should be indexed.
add_filter( 'algolia_should_index_searchable_post', 'exclude_algolia_filter_post', 10, 2 );
add_filter( 'algolia_should_index_post', 'exclude_algolia_filter_post', 10, 2 );