这完全取决于用户在您的网站上注册的方式。

TLDR 下面的代码允许您从指定自定义用户名的管理区域创建自定义用户，或使用GENERATE_CUSTOM_SEQ_USERNAME 生成顺序编号的。如果使用注册表，而不是wp-login.php 刚刚设置好user_login 到GENERATE_CUSTOM_SEQ_USERNAME 并使用CSS隐藏字段。

如果他们将通过wp-login.php 注册页面，首先需要允许为空user_login 输入字段：

/**
 * Filters the errors encountered when a new user is being registered.
 *
 * The filtered WP_Error object may, for example, contain errors for an invalid
 * or existing username or email address. A WP_Error object should always returned,
 * but may or may not contain errors.
 *
 * If any errors are present in $errors, this will abort the user\'s registration.
 *
 * @since 2.1.0
 *
 * @param WP_Error $errors               A WP_Error object containing any errors encountered
 *                                       during registration.
 * @param string   $sanitized_user_login User\'s username after it has been sanitized.
 * @param string   $user_email           User\'s email.
 */
add_filter( \'registration_errors\', \'smyles_allow_wp_login_register_empty_user_login\', 9999, 3 );

/**
 * Allow empty user_login (username) from wp-login.php registration form
 *
 *
 * @since @@version
 *
 * @param $errors WP_Error
 * @param $sanitized_user_login
 * @param $user_email
 *
 * @return mixed
 */
function smyles_allow_wp_login_register_empty_user_login( $errors, $sanitized_user_login, $user_email ){

    // First remove empty_username error code to make sure there aren\'t any other errors
    $errors->remove( \'empty_username\' );
    $error_codes = $errors->get_error_codes();

    // Return errors and don\'t process further (we only want to proceed when empty_username is only error code)
    if( ! empty( $error_codes ) ){
        return $errors;
    }

    return $errors;
}

这是通过过滤注册错误来完成的wp-login.php 以及移除empty_username 一

接下来，您将需要一个helper函数来生成带有填充零的顺序用户名。此函数使用10个字符的长度，每个新用户增加一个字符。这还验证了在将user\\u登录设置为该值之前，该登录不存在。

/**
 * Generate sequential padded user_login
 *
 * @author Myles McNamara
 *
 * @return string
 */
function smyles_generate_next_seq_user_login(){

    // Use 0 as default (if option does not exist yet), as 1 will be used for first user
    $last_user_num = get_option( \'smyles_custom_seq_usernames_last_id\', 0 );

    // Create padded username total length of 10 characters, increasing last ID by 1
    $gen_user_login = str_pad( (int) $last_user_num + 1, 10, 0, STR_PAD_LEFT );

    if( username_exists( $gen_user_login ) ){
        // If generated new user login exists, update our last id +1 and do recursive call
        update_option( \'smyles_custom_seq_usernames_last_id\', (int) $last_user_num + 1 );
        return smyles_generate_next_seq_user_login();
    }

    return $gen_user_login;
}

然后需要在user_login 由处理wp_insert_user 作用因为我们允许wp-login.php 传递空user_login 从register_new_user 函数，然后可以检查该值是否为空，并返回自定义生成的值。

你也会注意到我加入了GENERATE_CUSTOM_SEQ_USERNAME 检查是否通过user_login, 如果要使用CSS隐藏用户登录字段（在任何其他注册表中），并让其生成user_login 不会为空用户名引发错误。由于该用户名在技术上永远不应该存在，您可以将其用作占位符来确定是否应生成用户名。

This also allows you to create a new user in admin area, and just set GENERATE_CUSTOM_SEQ_USERNAME as username, and it will generate sequential numbered one for you, 或者创建自己的自定义。

add_filter( \'pre_user_login\', \'smyles_custom_username_seq_pre_user_login\' );

/**
 * Set user_login to generated value, only if passed value is empty
 *
 * @author Myles McNamara
 *
 * @param $sanitized_user_login
 *
 * @return string
 */
function smyles_custom_username_seq_pre_user_login( $sanitized_user_login ){

    $sanitized_user_login = trim( $sanitized_user_login ); // to match wp_insert_user handling

    /**
     * The user_login should be empty string when creating from wp-login.php registration page,
     * otherwise will contain a value when called by something else.
     *
     * There is a chance this will be called for updating a user (which is incorrect as wp_update_user should be called),
     * but even when updating a user, the passed user_login should have some type of value.
     */
    if( empty( $sanitized_user_login ) || $sanitized_user_login === \'GENERATE_CUSTOM_SEQ_USERNAME\' ){
        $sanitized_user_login = smyles_generate_next_seq_user_login();
    }

    return $sanitized_user_login;
}

下一步是更新选项中最后使用的ID，但只有在验证用户确实已创建（并且没有其他错误导致创建用户失败）之后：

/**
 * Filters a user\'s meta values and keys immediately after the user is created or updated
 * and before any user meta is inserted or updated.
 *
 * Does not include contact methods. These are added using `wp_get_user_contact_methods( $user )`.
 *
 * @since 4.4.0
 *
 * @param array   $meta                 {
 *                                      Default meta values and keys for the user.
 *
 * @type string   $nickname             The user\'s nickname. Default is the user\'s username.
 * @type string   $first_name           The user\'s first name.
 * @type string   $last_name            The user\'s last name.
 * @type string   $description          The user\'s description.
 * @type bool     $rich_editing         Whether to enable the rich-editor for the user. False if not empty.
 * @type bool     $syntax_highlighting  Whether to enable the rich code editor for the user. False if not empty.
 * @type bool     $comment_shortcuts    Whether to enable keyboard shortcuts for the user. Default false.
 * @type string   $admin_color          The color scheme for a user\'s admin screen. Default \'fresh\'.
 * @type int|bool $use_ssl              Whether to force SSL on the user\'s admin area. 0|false if SSL is
 *                                          not forced.
 * @type bool     $show_admin_bar_front Whether to show the admin bar on the front end for the user.
 *                                          Default true.
 * }
 *
 * @param WP_User $user                 User object.
 * @param bool    $update               Whether the user is being updated rather than created.
 */
add_filter( \'insert_user_meta\', \'smyles_custom_username_seq_verify\', 10, 3 );

/**
 * Verify user was created, and then increase option value
 *
 *
 * @author Myles McNamara
 *
 * @param $meta
 * @param $user WP_User
 * @param $update
 *
 * @return mixed
 */
function smyles_custom_username_seq_verify( $meta, $user, $update ){

    // Don\'t want to verify if this is just an update call
    if( ! $update && $user && $user->user_login ){

        // Check what the last user num was stored as
        $last_user_num = get_option( \'smyles_custom_seq_usernames_last_id\', 0 );

        // Verify that user_login of the user that was created, matches what is supposed to be the next user_login
        if( (int) $last_user_num + 1 === (int) $user->user_login ){
            // Update our option after verification
            update_option( \'smyles_custom_seq_usernames_last_id\', (int) $user->user_login ); // Type casting to int causes 0000000001 to be 1 (trim leading zeros)
        }

    }

    return $meta;
}

然后，您可能希望隐藏wp登录上的userlogin输入。php表单，您可以使用一些简单的CSS：

add_action( \'register_form\', \'smyles_hide_wp_login_username_field\' );

function smyles_hide_wp_login_username_field(){

    // Hide the first <p> element in registerform, which is the userlogin input
    echo \'<style>#registerform p:first-of-type { display: none; }</style>\';

}

https://gist.github.com/tripflex/1acacc19467122cdb1171a5e0b7300dd