如果这对其他人有帮助，下面是我的代码实现这一点的样子。根据tbuteler的建议，我最终根本没有保存附件数据，但我发现我可以直接使用$附件数组，而不是使用$请求：

function my_attachment_fields_to_edit( $form_fields, $post ) {
    $supported_exts = supported_types(); // array of mime types to show checkbox for

    if ( in_array( $post->post_mime_type, $supported_exts ) ) {
        // file is supported, show fields
        $use_sc = true; // check box by default (false not to, or use other criteria)

        $checked = ( $use_sc ) ? \'checked\' : \'\';

        $form_fields[\'use_sc\'] = array(
            \'label\' =>  \'Use SC\',
            \'input\' =>  \'html\',
            \'html\'  =>  "<input type=\'checkbox\' {$checked} name=\'attachments[{$post->ID}][use_sc]\' id=\'attachments[{$post->ID}][use_sc]\' /> " . __("Insert shortcode instead of link", "txtdomain"),
            \'value\' =>  $use_sc
        );
    }

    return $form_fields;
}

function my_media_insert( $html, $id, $attachment ) {
    if ( isset( $attachment[\'use_sc\'] ) && $attachment[\'use_sc\'] == "on" ) {
        $output = \'[shortcode url="\'.$attachment[\'url\'].\'"]\';
        return $output;
    } else {
        return $html;
    }
}

// add checkbox to attachment fields
add_filter( \'attachment_fields_to_edit\', \'my_attachment_fields_to_edit\', null, 2 );

// insert shortcode if checkbox checked, otherwise default (link to file)
add_filter( \'media_send_to_editor\', \'my_media_insert\', 20, 3 );