meta-value-check.php

<?php
/**
 * Plugin Name: 메타 값 체크 예제
 * Plugin URI:  https://gist.github.com/chwnam/2fb5cf06237a43671875c3baf12dca35
 * Description: 메타 값 저장 후 체크 예시
 * Author:      changwoo
 * Author URI;  https://blog.changwoo.pe.kr
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

add_action( 'init', function () {
	register_meta(
		'post',
		'_toggle_value',
		[
			'object_subtype'    => 'post',
			'type'              => 'boolean',
			'description'       => '',
			'default'           => true,
			'single'            => true,
			'sanitize_callback' => function ( $value ) {
				return filter_var( $value, FILTER_VALIDATE_BOOLEAN );
			},
			'auth_callback'     => null,
			'show_in_rest'      => false,
		]
	);

	register_meta(
		'post',
		'_last_value',
		[
			'object_subtype'    => 'post',
			'type'              => 'string',
			'description'       => '',
			'default'           => '',
			'single'            => true,
			'sanitize_callback' => function ( $value ) { return $value ? 'yes' : 'no'; },
			'auth_callback'     => null,
			'show_in_rest'      => false,
		]
	);
} );


add_action( 'add_meta_boxes_post', function () {
	add_meta_box(
		'toggle-control',
		'토글',
		function ( $post ) {
			?>
            <table class="form-table" role="presentation">
                <tr>
                    <th scope="row">토글 값</th>
                    <td>
                        <input id="_toggle_value"
                               name="_toggle_value"
                               type="checkbox" value="yes"
							<?php checked( (bool) get_post_meta( $post->ID, '_toggle_value', true ) ); ?>/>
                        <label for="_toggle_value">체크 값</label>
                    </td>
                </tr>
                <tr>
                    <th scope="row">이전 값</th>
                    <td>
						<?php echo esc_html( get_post_meta( $post->ID, '_last_value', true ) ); ?>
                    </td>
                </tr>
            </table>
			<?php
			wp_nonce_field( 'meta-value-check', '_mvc_nonce', false );
		}
	);
} );


add_action( 'save_post_post', function ( $post_id ) {
	$updated = func_get_arg( 2 );
	$nonce   = isset( $_REQUEST['_mvc_nonce'] ) ? $_REQUEST['_mvc_nonce'] : '';

	if ( $post_id && $updated && wp_verify_nonce( $nonce, 'meta-value-check' ) ) {
		$_last_value = (bool) get_post_meta( $post_id, '_toggle_value', true );
		update_post_meta( $post_id, '_last_value', $_last_value );

		$_toggle_value = filter_var(
			isset( $_REQUEST['_toggle_value'] ) ? $_REQUEST['_toggle_value'] : '',
			FILTER_VALIDATE_BOOLEAN
		);
		update_post_meta( $post_id, '_toggle_value', $_toggle_value );
	}
}, 10, 3 );