Register email as username

Question

I am using Wordpress 4.9.4 in a Wordpress Multisite, and I need to allow users to register using their email address as username. Looking at the code I found that what prevents me from accomplish that is that in the ms-functions.php there is a regular expression filtering usernames that have other characters than a-z, so when an email is the username I would get "Usernames can only contain lowercase letters (a-z) and numbers." I changed that regular expression in the ms-functions.php and it works fine. Now my question is, I don't want to have to recode the function wpmu_validate_user_signup every time I update my wordpress. What would be good practices regarding this issue? Should I create another includes/ms-functions.php in a theme_child? If so, can I create only this function or I have to copy the entire ms-functions.php?

Thanks

Answer 1

Emails can not be used as user names as wordpress uses user names by default as part of urls (for example the author page). Therefor it is not enough to let users register with email addresses, you also need to have some code to handler the URL related issues.

Anyway this sounds like an XY problem. Since users can login with their email address why would any one actually care what is their login handle created at registration time? The most simple thing to do is to create a registration form in which you create a "sanitized" user name for the user based on his email if you do not want him to think of one.

Answer 2

Here is a safer version of Gonzalo's filter, which only removes the validation error that reads "Usernames can only contain lowercase letters (a-z) and numbers.". It instead uses a similar validation but allows the same characters seen in sanitize_email().

The only caveat is this checks the error message name. If WordPress changes that error message in the future, this will stop working. But it's the only way to target that specific validation message.

/**
 * Allow users to sign up using an email address as their username. 
 * Removes the default restriction of [a-z0-9] and replaces it with [a-z0-9+_.@-].
 *
 * @param $result
 *
 * @return array $result
 */
function wpse_295037_disable_username_character_type_restriction( $result ) {
    $errors = $result['errors'];
    $user_name = $result['user_name'];

    // The error message to look for. This should exactly match the error message from ms-functions.php -> wpmu_validate_user_signup().
    $error_message = __( 'Usernames can only contain lowercase letters (a-z) and numbers.' );

    // Look through the errors for the above message.
    if ( !empty($errors->errors['user_name']) ) foreach( $errors->errors['user_name'] as $i => $message ) {

        // Check if it's the right error message.
        if ( $message === $error_message ) {

            // Remove the error message.
            unset($errors->errors['user_name'][$i]);

            // Validate using different allowed characters based on sanitize_email().
            $pattern = "/[^a-z0-9+_.@-]/i";
            if ( preg_match( $pattern, $user_name ) ) {
                $errors->add( 'user_name', __( 'Username is invalid. Usernames can only contain: lowercase letters, numbers, and these symbols: <code>+ _ . @ -</code>.' ) );
            }

            // If there are no errors remaining, remove the error code
            if ( empty($errors->errors['user_name']) ) {
                unset($errors->errors['user_name']);
            }
        }
    }

    return $result;
}
add_filter( 'wpmu_validate_user_signup', 'wpse_295037_disable_username_character_type_restriction', 20 );

Answer 3

I found another solution in a website. By adding this code to the top of the class of the registration plugin (in this case Gravity Forms) overrides the validation and allows the email to be used as username:

function custom_register_with_email($result) {

   if ( $result['user_name'] != '' && is_email( $result['user_name'] ) ) {

      $result['errors']->remove('user_name');

   }

   return $result;
}
add_filter('wpmu_validate_user_signup','custom_register_with_email');

Answer 4

If anyone stumbles across this - it's a (at time of writing)10-year old WP multisite "bug": https://core.trac.wordpress.org/ticket/17904

Someone has uploaded some MU plugin code similar to Radley's: https://gist.github.com/anttiviljami/01611cf3e74f7e7ae7a6