如果您不想使用插件，可以尝试实现一个元框来与该自定义帖子类型相关联，这是我在为某个帖子类型添加简单输入字段时使用的代码，在下面的示例中，我假设member_post_type 是您声明的帖子类型：

function member_add_meta_box() {
//this will add the metabox for the member post type
$screens = array( \'member_post_type\' );

foreach ( $screens as $screen ) {

    add_meta_box(
        \'member_sectionid\',
        __( \'Member Details\', \'member_textdomain\' ),
        \'member_meta_box_callback\',
        $screen
    );
 }
}
add_action( \'add_meta_boxes\', \'member_add_meta_box\' );

/**
 * Prints the box content.
 *
 * @param WP_Post $post The object for the current post/page.
 */
function member_meta_box_callback( $post ) {

// Add a nonce field so we can check for it later.
wp_nonce_field( \'member_save_meta_box_data\', \'member_meta_box_nonce\' );

/*
 * Use get_post_meta() to retrieve an existing value
 * from the database and use the value for the form.
 */
$value = get_post_meta( $post->ID, \'_my_meta_value_key\', true );

echo \'<label for="member_new_field">\';
_e( \'Phone Number\', \'member_textdomain\' );
echo \'</label> \';
echo \'<input type="text" id="member_new_field" name="member_new_field" value="\' . esc_attr( $value ) . \'" size="25" />\';
}

/**
 * When the post is saved, saves our custom data.
 *
 * @param int $post_id The ID of the post being saved.
 */
 function member_save_meta_box_data( $post_id ) {

 if ( ! isset( $_POST[\'member_meta_box_nonce\'] ) ) {
    return;
 }

 if ( ! wp_verify_nonce( $_POST[\'member_meta_box_nonce\'], \'member_save_meta_box_data\' ) ) {
    return;
 }

 if ( defined( \'DOING_AUTOSAVE\' ) && DOING_AUTOSAVE ) {
    return;
 }

 // Check the user\'s permissions.
 if ( isset( $_POST[\'post_type\'] ) && \'page\' == $_POST[\'post_type\'] ) {

    if ( ! current_user_can( \'edit_page\', $post_id ) ) {
        return;
    }

 } else {

    if ( ! current_user_can( \'edit_post\', $post_id ) ) {
        return;
    }
 }

 if ( ! isset( $_POST[\'member_new_field\'] ) ) {
    return;
 }

 $my_data = sanitize_text_field( $_POST[\'member_new_field\'] );

 update_post_meta( $post_id, \'_my_meta_value_key\', $my_data );
}
add_action( \'save_post\', \'member_save_meta_box_data\' );

Additional Resources for the WordPress Metaboxes: