如何设置meta-box中复选框的默认值 _WordPress开发

我知道这个问题出现了很多次, 但是我找不到答案。我有一个简单的复选框, 并且一切正常, 除了默认值始终为空。这是我的代码：

function portfolio_additional_settings($post) { $meta_port_cats = get_post_meta($post-> ID, '_portfolio_meta_cats', true); wp_nonce_field( 'update_portfolio_additional_settings', 'update_portfolio_additional_nonce' ); ?> < div> < input type="checkbox" name="portfolio_meta_cats_field" id="portfolio_meta_cats_field" value="http://www.srcmini.com/1" < ?php checked($meta_port_cats, 1); ?> /> < label for="portfolio_meta_cats_field"> < ?php esc_html_e( 'Categories', 'portfolio' ); ?> < /label> < /div> }function save_portfolio_additional_settings($post_id, $post) {$edit_cap = get_post_type_object( $post-> post_type )-> cap-> edit_post; if( !current_user_can( $edit_cap, $post_id )) { return; } if( !isset( $_POST['update_portfolio_additional_nonce']) || !wp_verify_nonce( $_POST['update_portfolio_additional_nonce'], 'update_portfolio_additional_settings' )) { return; }if(array_key_exists('portfolio_meta_cats_field', $_POST)) { update_post_meta( $post_id, '_portfolio_meta_cats', sanitize_text_field($_POST['portfolio_meta_cats_field']) ); } else { update_post_meta( $post_id, '_portfolio_meta_cats', null); } } add_action( 'save_post', 'save_portfolio_additional_settings', 10, 2 );

【如何设置meta-box中复选框的默认值】默认情况下如何通过检查？我究竟做错了什么？
谢谢。
#1进行如下操作：

< input type="checkbox" name="portfolio_meta_cats_field" id="portfolio_meta_cats_field" value="http://www.srcmini.com/< ?php echo $meta_port_cats; ?>" < ?php if ($meta_port_cats === '1'): ?> checked< ?php endif; ?> />